Year: 2026

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TNP-FW50 Charging Test: 5V/1A vs 5V/2A Fill Times

Short answer: on 5V input, a 5V/2A charger typically takes a TNP-FW50 from empty to full in 1.5 to 2 hours, while a 5V/1A charger takes roughly 2 to 3 hours — about an hour apart. That gap does not keep scaling with power, though: the charging circuit inside the pack caps the maximum current, so a stronger charger can only feed it up to that ceiling. Buying a bigger charger therefore has a clear limit to what it can return.

The TNP-FW50’s cells hold 1020mAh / 7.7Wh, which is a small capacity. The advantage of a small pack is fast top-ups; the disadvantage is that its useful sensitivity to input power is narrow — going from 1A to 2A is noticeable, going above 2A largely is not.

Where the numbers come from: theory versus reality

Start with a rough sum. A 7.7Wh pack on a 5W input (5V × 1A) would fill in about 1.5 hours in an ideal world; on 10W (5V × 2A) it would take under an hour. Real charging is not ideal, and three things eat into that.

  • Conversion losses: 5V has to be stepped down to cell voltage, and the charging circuit itself warms up, so efficiency typically lands around seventy to eighty percent.
  • The constant-voltage phase slows things down: above about 80% the pack switches to constant voltage, current tapers, and the last 20% often consumes forty percent of the whole process.
  • Cable drop: thin or long cables lose noticeable voltage at higher currents — the charger reads 5V while the pack sees perhaps 4.7V, and the circuit reduces current in response.

Allow for those three and 2 to 3 hours on 5V/1A and 1.5 to 2 hours on 5V/2A are sensible ranges. It also explains why so many people swap in a 2A charger and find it is nowhere near twice as fast: losses and the constant-voltage phase absorb most of the difference.

The two inputs side by side

Input Theoretical power Empty to full Where it fits
5V/1A (basic charger, old car adapter, computer USB port) 5W About 2-3 hours Overnight, casual top-ups at a desk
5V/2A (mainstream phone charger, most power banks) 10W About 1.5-2 hours Between takes, hurrying before you leave
5V/3A or a PD charger (still 5V after negotiation) Draw at the 5V tier Close to 2A, little gain Not worth buying for this pack

The third row is worth a sentence. The TNP-FW50 takes a standard 5V input and does not negotiate high-voltage fast-charge protocols, so plugging in a 65W PD charger just means it draws at 5V, and how much current it gets is set by the pack’s own limit. In practice the phone charger you already own is enough, and there is no need to buy a “fast charger” specifically for this battery.

The pack sets the current ceiling

This is widely misunderstood: people assume a more powerful charger means faster charging. In the constant-current phase, how much current actually goes in is decided by the charging management chip inside the pack; the charger only sets an upper bound on what is available. When the pack limits itself to around 1.2A, a 2A or 3A charger gives much the same result.

So between 5V/1A and 5V/2A the difference is real, while between 5V/2A and 5V/3A it is marginal. If your goal is saving time, replacing an old 1A charger with a 2A one works; replacing 2A with 3A does not.

What to actually choose: three suggestions

  1. One 5V/2A charger is enough on the road. It can feed a phone and the pack, and it is not bulky. Multi-port chargers are handier still, though watch that a single port is not being asked to share too much of the total.
  2. Cables let you down more often than chargers. Choose 20AWG or thicker and keep the length under a meter; the thin, soft cables bundled with devices drop noticeable voltage at higher currents.
  3. In a hurry, stop at eighty percent. The constant-voltage phase is where the time goes: 0 to 80% takes roughly half the total, so there is no need to wait for a full pack on location.

If you are charging the night before a trip, a 1A charger is perfectly adequate — plug in, go to sleep, and it is full in the morning. The scenario that genuinely calls for 2A is having an hour before you leave with an empty pack, and that is when the difference earns its keep.

Power banks and car adapters

With power banks, a common 10000mAh unit will fill a 7.7Wh pack three or four times over, but check that its output port supports 5V/2A auto-detection. Plenty of older banks only offer 5V/1A, which means slow charging the moment you plug in.

With car adapters, voltage fluctuates sharply as the engine starts, so plug in after the engine is running. Leaving packs in a hot car for long periods affects capacity far more than charging speed does — that matters more than which charger you pick.

If you often need to charge two packs at once, plugging cables in one at a time gets tedious; a dual-slot case is the smoother option, covered under the DR-FW50 dual-slot charging case. The list of compatible bodies for the pack itself is on the TNP-FW50 category page.

FAQ

Does charging at 5V/1A harm the pack?

No. Lower current is gentler on the cells and generates less heat; it is simply slower. What actually affects service life is heat and long-term storage at full charge, not slow charging.

Why is my 2A charger as slow as a 1A one?

Try a shorter, thicker cable first — most cases are cable drop causing the circuit to reduce current on its own. If a different cable changes nothing, the charger may be sharing its output across several ports at once.

Can I charge from a laptop’s USB-C port?

Yes, as long as the port supplies 5V. Some laptops cut power to their USB-C ports when asleep, which stops charging halfway, so avoid charging with the lid closed and the machine sleeping.

Does it stop automatically when full?

A properly designed pack switches to a trickle and then stops, so leaving it connected will not keep overcharging it. As a habit, unplugging once it is full is still safer and avoids pointless warmth.

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One Year In: How Much Capacity Does a Third-Party NP-FZ100 Lose?

Start with the answer. In our testing, a third-party NP-FZ100 after a normal year of use keeps roughly 85%–95% of its original usable capacity, meaning a loss of around 5%–15%. That lands in the same band we record for Sony’s own pack under comparable workloads. There is no widespread pattern of third-party cells collapsing inside a year. Three things separate a healthy pack from a tired one: how many cycles it has run, how you charge it, and where it spends its downtime. Below you’ll find the retention figures sorted by workload, our test protocol, and a clear line for deciding when to retire a battery. To run the same check yourself, follow the steps in how to spot a fake capacity rating.

What one year costs you, sorted by workload

Capacity doesn’t fade on the calendar. It fades with cycles plus storage conditions. Two packs bought on the same day can age very differently: one belongs to a commercial shooter who has run it through a hundred-plus cycles, the other sits in a weekend bag with a few dozen. The table below comes from our year-long tracking of a single batch of NP-FZ100 compatible batteries. Figures are given as ranges rather than precise single values.

Usage level Approximate cycles in year one Capacity retained (range) What it feels like in the field
Light: weekend walks, occasional top-ups Around 20–40 95%–99% Basically indistinguishable from new
Moderate: one or two shoots a week, two packs in rotation Around 50–80 90%–96% Tight at the end of a long day; bring a spare
Heavy: weddings, commercial work, frequent 4K Around 100–150 85%–92% One pack won’t cover half a day; rotate three or more
Poor storage: left full, cooked in a hot car Unrelated to cycles Possibly below 85% Noticeably short; replace early

One caveat worth more than the rows themselves: variation between two individual batteries inside the same row is often wider than the gap between rows. Two packs from the same batch, one living in a camera bag and one baking on a parcel shelf, can end the year more than ten percentage points apart.

Where the capacity goes: four main drivers

Cycle count does most of the work

Chemical aging in a lithium cell is tied to charge and discharge cycles. The industry shorthand is straightforward: expect roughly 80% remaining after 300–500 full cycles. That works out to a few percent lost per hundred cycles, which lines up with what we saw across the year. The full breakdown by stage is in what's left after 100 cycles.

Storing it full, and storing it hot

Leaving a pack parked at 100% in a warm place — a car in July, a sunny windowsill — accelerates the decline noticeably. This is also why a battery that “hasn’t been used much” can still test low. The damage came from the shelf, not the shutter.

High current draws add stress

Fast burst shooting, 4K and high-frame-rate recording, heavy use of IBIS and live view: all of it pulls more current, which means more heat and faster wear. Owners of high-speed bodies like the A9 series and A1 tend to notice it sooner.

Running it down to zero every time

Discharging until the camera shuts itself off, then charging back up, is a deep cycle and it costs the cell something. Shallow top-ups age far more slowly than full drain-and-fill habits.

How we measure: our lab protocol

We keep the conditions fixed so numbers stay comparable. Here’s everything that shaped the ranges above, so you can judge how far they transfer to your own kit.

  • Temperature: discharge tests run at room temperature, around 25°C. Cold weather behaves differently.
  • Method: constant-current discharge down to cutoff voltage, then compare the delivered charge against the original rating.
  • Sample size: multiple packs from the same batch are tracked together, and we report the observed range. A single outlier never becomes a conclusion.
  • Reporting: ranges and “around” only. Cell consistency varies batch to batch, so single-digit precision would be neither repeatable nor useful.
  • Cross-check: findings are confirmed in-camera, since what shooters actually care about is frames per charge, not milliamp-hours.

Treat these numbers as a way to judge whether aging is normal. They are not fine enough to rank brands against each other.

Third-party vs Sony: is there a real difference in the curve?

Under matched workloads, we have not observed any systematic fast-fade behavior unique to third-party packs. Both curve shapes look alike: gentle at first, steeper later. When an individual sample drifts off, the cause points back to cell batch or handling habits rather than to whether the pack came from Sony.

In fairness, batch-to-batch and environment-to-environment variation is real, so read this as a trend rather than a controlled head-to-head verdict.

Four signs it’s time to replace

  • Runtime drops to roughly 70% of a new pack. By then a full day is a gamble, and a replacement costs far less than a dead camera mid-shoot.
  • Around the two-year mark. Even with decent capacity left, internal resistance has usually climbed, and high-current work (bursts, 4K) will cut out early.
  • Any swelling. Stop using it. No charging, no discharging. Take it to a hazardous waste or battery recycling point; never puncture or burn it.
  • Full charge to half-empty in minutes. That points to internal resistance or a confused fuel gauge. Run one full charge-discharge cycle to recalibrate; if nothing changes, replace it.

FAQ

Is 10% loss in a year a defect?

No. Against the 80%-after-300–500-cycles benchmark, losing 5%–15% in twelve months is normal. If a pack falls below 80% within six months, and you can rule out heat and deep discharges, contact the seller for a check.

Do third-party packs always fade faster than originals?

Matched for workload, we don’t see a meaningful difference. Cycle count, time spent at full charge, and ambient temperature are what move the needle.

Does an unused battery degrade on its own?

It does, and storage habits matter a lot. Aim for 40%–60% charge, keep it cool and dry around 15–25°C, and top it up every three months. Both fully-charged and fully-empty storage age a cell faster.

Can lost capacity be restored?

No. Chemical aging is one-way, and “revival” tricks don’t work. What you can do is run a complete charge-discharge cycle so the remaining-charge display reads honestly again.

How should I dispose of a degraded pack?

Not in household trash. Drop it at a local hazardous waste or battery recycling point, ideally with tape over the terminals.

Bottom line and what to buy

Condensed: after one year a third-party NP-FZ100 usually still measures 85%–95%, which is normal wear. Think about replacing it around two years in, or once runtime falls near 70%. If your body belongs to the NP-FZ100 camp — A7 III/IV, A7R III/IV/V, A7S III, A9 series, A1, A6600, A6700, A7C series, FX3, FX30, ZV-E1 — add a YO NP-FZ100 compatible battery (2280mAh / 7.2V / about 16.4Wh) at around $17.89, or step up to the TNP-FZ100 (2400mAh / about 17.3Wh) at around $19.66 for a little more headroom. Kits run about $22.93 for one battery with a charger and about $36.74 for two batteries with a charger. Sony’s original NP-FZ100 sells for $70 and up. For day-to-day upkeep, the checklist in five habits that extend NP-FZ100 life covers the basics. Studios, rental houses, and resellers buying 100 units or more should reach us through the wholesale inquiry page for volume pricing.

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DR-FW50 LED Not Lighting: A Five-Step Diagnosis

Short answer: most of the time a dead indicator points to the supply chain rather than the battery. Work through cable, then adapter, then bay, then battery, then contacts, and you will usually localize it within ten minutes. The order matters: outside in, cheap to expensive, so you do not condemn a healthy battery before you have established the cause.

The DR-FW50 is a two-bay charging case with no battery and no storage of its own; it only starts working once power is connected. That is the key to diagnosis. A dark case may be getting no power at all, or it may be powered but not detecting a battery — and the two look almost identical.

First, confirm when the light should be on

Normally, with power connected and a battery loaded, that bay’s indicator lights up and shows charging by staying steady or pulsing, then changes color or goes out when full. An empty bay usually stays dark or shows only a power indicator.

So the first false alarm to rule out is an empty bay, or a battery that never seated. An FW50 has to be pressed to the bottom of the bay with full contact before the detection spring moves. Plenty of people leave the battery riding high; the lid closes and it looks installed, but no current flows.

The second is the supply itself. The case’s input is typically USB-C and needs 5V. Some older adapters, computer USB ports and car chargers cannot deliver enough, and the case drops into a protection state that looks like no response at all.

The five-step method

  1. Swap the cable. Substitute a cable you know charges a phone reliably. USB-C cable quality varies widely, and cheap charge-only cables sometimes cannot even deliver stable power.
  2. Swap the adapter. Use a known-good 5V adapter straight into a wall socket — no power strip, no extension cord, no USB splitter. This rules out an inadequate supply.
  3. Swap the bay. Move the battery from the left bay to the right. If it lights up in the other bay, the original bay’s spring or circuit is faulty, which is a case defect.
  4. Swap the battery. Try a battery you know works. If the light comes on with a different battery, the problem is the original one — over-discharged, protection board latched, or oxidized contacts.
  5. Clean the contacts. With power disconnected, wipe the contacts in the case and on the battery with a dry cotton swab, then blow out loose dust. Do not scrape with a metal pin; once the plating is broken, oxidation accelerates.

After those five steps you will usually know which link failed. None of it requires opening the case, and opening it is not advisable — the charging circuit is inside, and under non-professional conditions the risk outweighs any chance of repair.

What each result tells you

Recovers after swapping Where the fault is What to do
Lights after a cable swap Original cable cannot deliver enough, or has a broken conductor Replace the cable; demote the old one to low-demand devices
Lights after an adapter swap Original adapter output too low or incompatible Use a standard 5V adapter; avoid cheap car chargers
Lights after a bay swap Original bay’s spring deformed or contacts dirty Clean the contacts; if it still fails, contact support
Lights after a battery swap Original battery over-discharged, protection tripped, or contacts oxidized Clean contacts first; a deeply discharged battery may recover on a slow charge
Lights after cleaning contacts Contact resistance too high for detection Make cleaning a routine
No light after all of the above Fault inside the case Stop using it and contact support

Only the last row needs service. The first five are yours to fix, and contacts in particular are the most common cause of a dark two-bay case.

Three dark-light situations that are normal

The battery is already full. Some designs stop showing a charging indication once a full battery is detected, or give only a brief signal. If you put a freshly charged battery in, no light is expected. Test by trying a battery you know is empty.

The battery voltage is very low and pre-charging has begun. A battery left unused for a long time can drift down, and the case will first trickle a small current into it; the indicator may come on late, only once voltage passes the threshold and normal charging starts. Give it fifteen minutes and look again.

Temperature protection. A battery that has been in a hot car, or one that is still warm from shooting, can cause the case to pause charging on temperature, with no light. Let it return to room temperature and try again; it usually recovers.

None of these is a fault, and returning a perfectly good unit over them wastes both time and shipping.

There is also a way to test around the case: if you own a battery with a USB-C port, such as the YO TNP-FW50, charge it directly from an adapter and see whether it takes power. If it does, the battery is fine and the case is the problem; if it does not, go back and inspect the battery.

When to stop. If the case produces a smell while powered, the shell becomes noticeably hot, or the indicator blinks abnormally rather than holding a steady or pulsing pattern, disconnect power at once. Those point to an internal circuit fault, and continuing to use it carries risk.

Also, never put a swollen battery into the case. Pressure from the closing lid worsens the swelling, and this is one of the few scenarios with a genuine safety hazard — not something to try “just to see.”

Day-to-day maintenance is simple: wipe the contacts after each use, keep the case in a ventilated spot, and do not leave it plugged in permanently. Those three habits make a dark indicator much less likely. More on using both bays is on the DR-FW50 category page, and battery specifications are on the NP-FW50 series page.

FAQ

The light is off, but the battery works in the camera. What does that mean?

It means the battery is healthy and the fault is on the case side, so focus on the cable, the adapter and the bay contacts. If the camera recognizes the battery, its protection board and contacts are working.

Only one of the two bays lights. Is the case broken?

Not necessarily. Swap the two batteries once: if the problem follows the battery, it is the battery; if it stays with the same bay, it is the case.

Can I use a fast charger to power the DR-FW50?

Yes, but the case only draws what it needs. A fast charger negotiates down to the 5V level and will not force a higher voltage in. The real thing to avoid is a poor-quality adapter that cannot deliver enough current.

The indicator stays on and never goes out. Is that normal?

No. It should change color or go out when charging finishes. Staying lit for a long time usually means the battery cannot be judged full, which may point to an aged battery or poor contact.

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TNP-FW50 in NEX and First-Gen A7 Bodies: Will It Warn?

Short answer: on older bodies such as the NEX-5N, NEX-6, NEX-7 and the first-generation A7, a TNP-FW50 will usually power on, shoot and report charge normally. Some older firmware may show a message along the lines of “battery not recognized” or “use a genuine battery”, which you acknowledge and then carry on; image quality and features are unaffected. It would be wrong to claim there is never a message, because the logic lives in body firmware and the versions still in the field are very mixed. What is certain is that a message is only a message — the pack still supplies power properly.

Owners of older bodies arguably need this pack more than owners of new ones, for a simple reason: neither the NEX series nor the first A7 supports in-body USB charging, so the pack has to come out for a dock. Lose the dock and the whole kit is stuck. A direct-charge pack breaks that dependency.

What “error” actually means

Break the word down first. A third-party pack on an older body can produce three different situations, of very different severity.

  • A message: a line of text at power-on, roughly “cannot confirm battery information” or “a genuine battery is recommended”. Acknowledge it and shooting continues. This is by far the most common.
  • Wrong charge display: no percentage, only bars; or full the moment you fit it, then suddenly one bar. This is incomplete decoding.
  • Will not power on: rare, and usually a serious mismatch between the decoding chip and the firmware. If you meet one, exchanging the pack is more practical than fighting the camera.

The third is the one worth worrying about, and it is uncommon. Almost all reports concern the first: a message appears, and then everything works.

Model-by-model

The table runs in order of body age and gives the expected behaviour plus what to watch. The “message” column says “may”, not “will”, because the same model on different firmware behaves differently.

Body Battery Compatibility Watch for
NEX-5N NP-FW50 Mostly fine, some firmware may warn No in-body USB charging, so direct charging gains the most
NEX-6 NP-FW50 Mostly fine, charge may show as bars only Hybrid AF body, moderate power draw
NEX-7 NP-FW50 Mostly fine, some firmware may warn 24 megapixels, thirsty among older bodies
A7 (ILCE-7) NP-FW50 Mostly fine, may warn Full frame, runtime was tight to begin with
A7R (first generation) NP-FW50 Mostly fine, may warn Slow high-resolution writes, noticeable standby drain
A7S (first generation) NP-FW50 Mostly fine, may warn Video-oriented body, watch heat in long takes
A7 II / A7R II / A7S II NP-FW50 Usually better than the first generation In-body stabilization added, so draw goes up

The column worth remembering is the last one. Older bodies were never generous on runtime, and the NEX-7 and first A7 drain quickly in the cold or when left on standby, so carrying a spare you can top up anywhere matters far more than whether a percentage is displayed. Model-by-model fit notes are collected on the TNP-FW50 category page for cross-checking.

Why firmware version changes the result

Battery identification logic lives in firmware, and Sony adjusted its handling of third-party packs between releases. Two owners of the same A7 can report different things: one updated to the final firmware and no longer sees a message, another stayed on the factory version and still does. Both accounts can be true — the firmware is simply different.

Updating firmware purely to remove the message is not advisable. Updates for older bodies often touch lens compatibility lists and other details as well, so the benefit is unclear and the risk is not. A power-on message costs one button press; a corrupted mainboard costs a repair.

What to do when a message appears

  1. Acknowledge it and go straight into shooting, first confirming that the shutter, autofocus and playback all behave normally.
  2. Watch the charge indication. If it falls smoothly, decoding is essentially matching and the pack is fine to use.
  3. If the gauge jumps badly, try the pack in a second body to separate a pack problem from a firmware problem in that camera.
  4. If it will not power on or keeps cutting out, stop and arrange an exchange; do not keep reinserting it to test.

Following that order, the great majority of cases are settled as usable within the first two steps. The proportion that genuinely needs a return is very small.

Why older bodies gain more from direct charging

The NEX-5N, NEX-6, NEX-7 and first-generation A7 do not support in-body USB charging — that is simply how they were designed. Your charging method is therefore tied to one plastic dock: lose it, break it or leave it in a hotel, and the packs are dead weight.

The TNP-FW50 puts a USB-C port on the pack itself, which effectively adds a capability these cameras never had. Topping up from a power bank for an hour in a café is far more realistic than hunting for a socket. The dock-based approach of that era is covered in NP-FW50 batteries and charging accessories; if you have several packs, a dual-slot case is handier still.

One related note: paired with these older bodies, an OEM pack also holds 1020mAh, so there is no such thing as a new pack with more capacity than an old one. If a new pack feels like it lasts longer, it is almost certainly because the old one has been through several hundred cycles and its real capacity has long since dropped.

FAQ

Does a “not a genuine battery” message affect image quality?

No. The message concerns battery identification only and has nothing to do with the imaging chain. Shutter, autofocus, color and video specifications are all unaffected.

Can the NEX-5N show a battery percentage?

Some firmware versions show bars only, without a percentage. That is a display difference, not a functional one, so judge remaining charge from the bars.

Does charging the pack directly risk damaging an older camera?

No. Charging happens inside the pack and the camera is not involved. What the pack delivers to the body is still a 7.2V nominal output, identical to the original, so there is no path by which charging voltage reaches the camera.

A pack sat unused for two years — can it be recovered?

Long storage lets a lithium pack self-discharge to a very low voltage, and whether it recovers depends on whether the protection board has latched off. If half an hour on charge produces no response at all, it is reasonable to give up rather than keep trying.

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Three NP-FZ100 Cells Compared: Capacity, Resistance and Heat

For this comparison we took three NP-FZ100 cells from the same general price band — call them samples A, B and C, with no brands named — and ran them through one procedure at room temperature, measuring usable capacity, approximate DC resistance and temperature rise during charging. In our lab testing, all three landed in the neighborhood of their rated capacity, separated by only a few percentage points. Resistance differed more, and tracked with how each behaved under load. Charging temperature rise stayed in the “slightly warm” band for all three, with no meaningful spread between them.

Everything here is presented as a range. The sample count is small, individual measurements drift, and the intent is to show the method and the scale of the differences — not to certify one specific product.

Method and conditions

  • Ambient temperature: a normal indoor range, no direct airflow across the samples, logged throughout.
  • Charging: one known-good charger for all samples, then a rest period after the indicator turned green before discharge began.
  • Discharge: constant-current electronic load, with the cutoff set to the usual lower limit for a 7.2V nominal pack; three runs per sample, reported as a range.
  • Resistance: approximate DC method (voltage drop across load ÷ current), not a four-wire AC measurement — good for ranking, not for absolute values.
  • Temperature: measured at the same point on the shell, recorded as the difference between surface and ambient at the end of charging.
  • Samples: three cells bought at random, unopened, with no pre-screening.

The value of this setup is comparison under identical conditions. Absolute numbers describe these samples only; the spread between them is what carries over.

Results and what each one means

Item Sample A Sample B Sample C Our read
Rated capacity Around 2280mAh Around 2280mAh 2400mAh class C is rated higher
Usable capacity measured Roughly 2150–2250mAh Roughly 2100–2210mAh Roughly 2250–2350mAh All above 90% of rating
Capacity achieved About 95%–98% About 93%–97% About 95%–98% A few points apart
Approx. DC resistance Low-to-mid range Low-to-mid range Low-to-mid range B ran slightly higher
Shell temperature rise Slightly warm Slightly warm Slightly warm Comparable across all three
Consistency across repeats Tight Looser Tight Matches the resistance result

Condensed into one line: capacity is not where these cells separate — consistency is. The gap in usable capacity is much smaller than the gap in how they behave under heavy load.

Capacity: why the measurement always lands under the label

Start by clearing up a common misreading: a 2280mAh rating does not promise 2280mAh delivered. The label is a typical value under a specific temperature, discharge rate and cutoff. In a camera:

  • Discharge rates are higher: the body pulls far more current than a gentle bench discharge, so usable capacity drops.
  • Cutoff arrives earlier: the camera declares empty while there is still charge left, to keep itself running properly.
  • Temperature is not ideal: below room temperature, usable capacity falls noticeably.

In our testing, achieving around 90% or more of the rated figure usually indicates an honest label. Coming in well under roughly 80% is a reasonable trigger to suspect the rating. The check is described in how to spot inflated capacity ratings.

Resistance: the number behind “it still had two bars”

A cell with higher resistance behaves fine at low current, then sags the moment you ask for real power — fast bursts, repeated flash recycling, starting a 4K clip. The body reads the sag as empty and sometimes shuts down. That is why some cells stop working while the gauge still shows charge.

  • When new: our three samples sat close together in the low-to-mid range.
  • After cycling: how fast resistance climbs is the real separator, and that takes long-term use or accelerated cycling to see.
  • What you can feel instead: at the same indicated level, whether burst slows down and flash recycling drags.

For weddings, sports and anything you cannot pause, weight those load behaviors — or the feel-based equivalents — more heavily than the capacity number on the label.

Temperature: what it means that all three were similar

Heat during charge and discharge is normal physics. In our testing, all three samples finished a standard charge only slightly warm to the touch, with none hot. Points worth keeping:

  • Rise tracks charge current: a faster charging setup means noticeably more heat.
  • Heat accelerates aging: cells that live hot lose capacity sooner.
  • Don’t charge in a sealed space: a padded bag divider or a sunlit car interior both trap heat.
  • Hot means stop: slightly warm is fine, hot is a signal to investigate.

The broader safety picture is laid out in our guide to third-party camera battery safety.

Turning the comparison into a buying decision

  • Don’t agonize over a few dozen mAh: the felt difference between 2280mAh and 2400mAh is small — see 2280mAh versus 2400mAh.
  • Favor clear warranty terms and traceable labeling: what you cannot see inside the pack has to be backed by someone taking responsibility. See the NP-FZ100 warranty page.
  • Buy several from one batch: a single batch tends to be more consistent and makes rotation by number simple.
  • Watch what you can verify yourself: how many frames you actually get from a full charge, and whether burst slows — more useful than any spec sheet.
  • On a tight budget, buy quantity: an extra cell usually pays off more than a slightly higher rating.

The structural view — cells, protection board, communication circuit — is in inside a third-party NP-FZ100.

FAQ

Why not publish exact milliamp readings?

Single measurements drift with environment and equipment, and over-precise figures mislead more than they inform. Ranges represent the real scale of the differences and keep the data honest.

Why only three samples?

Time and sample availability set the limit. Three are enough to answer “how much do cells in this price band differ,” but not enough to draw conclusions about any specific brand.

Does higher capacity achieved mean a better cell?

Not on its own. Read capacity alongside resistance, retention after cycling and warranty terms. Capacity alone hides how a cell behaves under load.

Can I repeat any of this at home?

Capacity and runtime can be approximated by counting frames through a fixed shooting routine. Resistance needs a proper load; for most people, feel-based observation is enough, and buying gear purely to measure is not worth it.

Our NP-FZ100 compatible battery is rated 2280mAh / 7.2V / around 16.4Wh, at around $17.89 per cell, around $22.93 for one cell with a charger and around $36.74 for two cells with a charger. For more capacity, the TNP-FZ100 (2400mAh / around 17.3Wh) runs around $39.92 for the two-cell kit. Reviewers, purchasing teams and studios wanting to run their own sample comparisons are welcome to use the wholesale inquiry page for volume pricing and same-batch samples.

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Can You Fly With a DR-FW50? Lithium Battery Rules

Short answer: the DR-FW50 is a charging case with no cells inside, so carrying it alone is not subject to lithium battery transport limits; the restrictions apply to the NP-FW50 batteries loaded into it. A single FW50 is rated at 7.7Wh, far below the usual 100Wh carry-on threshold, so it can fly in the cabin — but it generally may not go into checked baggage. In other words, the case can travel any way you like; the batteries have to board with you.

What follows is general air transport practice and hands-on experience. Individual carriers may apply stricter terms, so check your airline’s own guidance before departure, especially on international routes.

The rules look at the battery, not the case

Security screening assesses lithium content and watt-hours, not what an object is called. A charging case contains no cells, only a circuit board and spring contacts; in transport classification it is closer to a plastic accessory and can be carried or checked.

The moment you load batteries into it, though, the whole thing is treated as a container holding lithium batteries. What decides whether it passes is then the number of batteries and their watt-hours, not the shape of the case.

So the useful question is not “can the DR-FW50 fly” but “how many NP-FW50 batteries are in the case, at what watt-hours, and in which bag.” Answer those three and the problem is solved.

The math: what an FW50 is actually rated

Item Value Note
Nominal voltage 7.2V NP-FW50 specification
Nominal capacity 1020mAh About 1.02Ah
Nominal energy 7.7Wh Voltage times capacity; the commonly printed figure
Typical carry-on limit 100Wh Below this, approval is usually unnecessary
Share of the limit, one battery Under 8% Ample headroom

To put 7.7Wh in perspective: a common phone power bank is 37Wh or 74Wh. One FW50 holds less than a third of the energy of a mid-sized power bank. On quantity, most airlines take a relaxed view of spares for personal use — four or five for a few days of shooting is not a problem — but do not turn up with dozens in one bag, which reads as commercial transport.

Note that the rules address spare batteries, meaning those not installed in a device. The one in the camera is treated as part of the equipment and is usually subject to looser limits.

Four steps before security

  1. Take every battery out of checked luggage. Spare lithium batteries normally have to stay with you, and this is the rule most often overlooked and most often the reason a bag gets opened.
  2. Insulate the terminals. Put each battery in its own plastic bag, or seat it in a DR-FW50 bay with the lid closed. The aim is to keep the contacts from bridging against keys or coins.
  3. Keep them together and easy to inspect. One clear bag or one case means you can lift the whole lot onto the tray instead of rummaging.
  4. Do not go out of your way to declare a 7.7Wh battery. Spares under 100Wh normally need no airline approval, but cooperate with screening and answer questions honestly.

Domestic routes are usually handled loosely; international itineraries may involve a second check at a transfer. Keeping the batteries within easy reach is the least troublesome approach.

The usual reasons for being stopped. In the great majority of cases it is not excess watt-hours but one of these: batteries loose in checked baggage, spotted on X-ray; batteries mixed with metal objects and judged a short-circuit risk; quantities far beyond personal use, prompting a request to explain; or a cracked or swollen casing, refused on safety grounds.

Swelling is the one with no room for argument. A lithium battery with a deformed shell can be refused at any stage, check-in included. Inspecting your batteries before you leave is far more effective than arguing at the airport.

There is also the case of the charging case itself being pulled for inspection. That is not a violation — the interior has circuitry, the X-ray image is busy, and the officer needs to confirm there are no hidden cells. Open the lid and cooperate.

Where checked and carry-on divide

A simple rule: the case can be checked, the batteries must stay with you. If baggage allowance is tight, put the empty case in the checked bag and carry the batteries in a separate pouch. That saves cabin space without breaking any rule.

Checking a camera with the battery installed is permitted by most airlines, but power it off, remove the memory card, and confirm the battery is not swollen. The safer practice is still to take the battery out and carry it with you.

If you also travel with an FZ100-system body, the logic is identical and only the watt-hours change; see the NP-FZ100 flight guidance. General information on the FW50 system is on the NP-FW50 series page, and how to use the case is on the DR-FW50 category page.

One more point: because the YO TNP-FW50 has a USB-C port on the battery itself, people often ask about topping it up from a power bank in flight. Whether seat power is available depends on the aircraft and the airline, and a battery on charge counts as in use; it is safer not to charge and discharge for long stretches on board and to top up after landing.

FAQ

Can an empty DR-FW50 be checked?

Yes. A charging case with no cells falls outside lithium battery transport rules, so neither checking nor carrying it is restricted. It is still worth emptying the bays so the lid is not stressed in transit.

Will security ask me to open a case with batteries inside?

Possibly. When they need to confirm there are no hidden cells, they will ask you to open the lid. That is routine inspection, not a violation; just cooperate.

How many NP-FW50 batteries can I bring?

Most airlines apply a “reasonable personal use” standard to spares under 100Wh, and four or five for personal shooting is normally fine. Quantities clearly beyond personal use may prompt a request to explain their purpose.

Can batteries go in checked baggage?

Generally no. Spare lithium batteries are required to travel in the cabin, which is a standard international expectation. Batteries installed in a device face looser limits, but checking them is still not advisable.

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Spotting a Fake NP-FW50: Shell, Printing, Decoding, Weight

Short answer: to judge whether an FW50 is a counterfeit, work through four steps — check the shell’s mold lines and finish, check the printed type and its position, check whether the camera recognizes the pack and reports charge reliably, and weigh it against a known pack. If two or more of the four come up wrong, it is almost certainly a fake. One distinction first: a legitimate third-party pack such as the YO TNP-FW50 clearly labels its own brand and does not pretend to be Sony, whereas a counterfeit carries the SONY mark and imitates the original. Those are entirely different things.

The FW50 attracts fakes because it has had a long production life, huge installed base, low unit price and steady demand. The counterfeiter’s goal was never to make a good battery but to make you believe you bought an original. So the question is not whether the pack performs well — it is whether it lies about what it is.

Step one: shell and mold lines

An OEM FW50 shell is a two-shot molding, and the parting line is fine and even, almost imperceptible under a fingertip. Fakes are limited by tooling precision and cost, so the line is usually coarser and rougher and catches a fingernail. Check three places: the long edges on both sides, the bottom corner nearest the contacts, and around any port cover or interface opening.

The material differs too. The OEM shell is fairly matte with a faint frosted texture, and after long use it goes uniformly glossy; fakes often use regrind, look gray or yellowed, develop shiny patches and tend to crack at the latch.

One more point that gets missed: the contacts. OEM contacts are gold-plated, warm in tone, evenly spaced and consistent in spring force. Fakes are often nickel-plated or bare copper, white or reddish, and show obvious scoring after a few insertions.

Step two: printing and typeface

Printing is the cheapest thing to fake and the easiest place to give yourself away. OEM print is crisp and sharp, set in a custom typeface with even letter spacing; fakes usually use a generic font, and under magnification the edges are soft and the stroke weights uneven.

What to look at Genuine Typical fake
Letter edges Sharp, no ink spread Soft, feathered or doubled
Model and capacity text Fixed position, aligned to a baseline Offset, crooked, not centered in the recess
Certification marks Correct proportions, even line weight Distorted proportions, lines blurring together
Serial number Laser-marked with depth variation Ink printed, rubs off
Origin and warning text Airy layout, sensible line breaks Crammed together, typos or odd phrasing

The last row deserves its own note. Fake warning text is often copied from a different model, so you see small slips such as “lithium battery pack” where it should read “lithium-ion battery pack”, or the voltage given as 7.4V instead of 7.2V. The FW50 is rated 7.2V / 1020mAh / 7.7Wh; if those three numbers do not line up, stop there.

Step three: decoding and camera communication

This step needs a camera. Fit the pack, power up and watch three things: whether a battery-related message appears, whether the charge indication moves continuously, and whether low battery still triggers a normal shutdown.

A genuine OEM pack and a properly made third-party pack both behave consistently on all three. Fakes typically show one of these: the gauge sits at 100% for a long time and then jumps to 10%; or the number leaps when you power off and on again; or the camera shuts down with plenty of capacity apparently left. All of these mean the decoding chip is only reporting numbers rather than reading the cells.

Bear in mind that older bodies (the NEX series, the first-generation A7) may show a message with third-party packs in any case, so this step has to be read alongside the specific model — it cannot be generalised. Model-by-model notes are in the TNP-FW50 compatibility section; if you are more interested in the OEM specification, compare against the ratings in the NP-FW50 battery section.

Step four: weight and feel

The hardest part to fake is the cell. An OEM FW50 bare pack usually comes in a little over 40 grams, and a gram or two either way is normal. Fakes cut cost with low-density cells and often feel clearly light; occasionally it goes the other way, with a steel slug added inside to give heft, taking the weight over the norm.

So compare rather than trusting your hand. Take three packs of the same model, weigh each on a kitchen scale: within 3 grams of each other is fine, more than 5 grams apart is worth suspicion. A rattle when you shake it also suggests poor assembly.

Feel includes the damping as the pack goes into the camera. A genuine pack slides in with even resistance and the latch clicks home; a fake is either loose enough to shift or so tight it needs force, which over time wears the latch in the camera’s battery bay.

Combine the four into one quick list to run through before you buy:

  1. Are the mold lines fine and even, the shell matte, the contacts gold-plated?
  2. Is the printing sharp, and do 7.2V / 1020mAh / 7.7Wh all agree?
  3. Does the camera recognize it consistently, is the gauge smooth, does low-battery protection work?
  4. Does it weigh a little over 40 grams, and do same-model packs sit within 5 grams of each other?

Two or more failures across the four is enough to call it. Conversely, if you bought a compatible pack that clearly states its own brand, it should not carry a Sony mark at all, and holding it to a “looks like the original” standard is unfair — what you are judging is whether it is honestly labeled and works reliably.

FAQ

Is a pack without a Sony logo automatically fake?

No. A legitimate third-party pack should not carry a Sony logo, and printing one would be infringement. The test is whether it impersonates, not whether it comes from a third party.

Is a very low price a sure sign of a fake?

Not necessarily. Compatible packs are legitimately much cheaper than OEM, which is a property of the category. The real red flag is a fake sold at OEM money, or a price so low it defies reason alongside a claim of being genuine original stock.

Can a fake damage the camera?

The risk sits mainly with the pack itself: inconsistent cells and a crude protection board can cause abnormal heat or sudden cutouts. The camera usually has its own protection, but using poor packs long term is not a good habit.

Is a used OEM pack worth buying?

Look at cycle count and age. The FW50 starts with modest capacity, and a worn pack may be down to sixty or seventy percent, so a low price may still not be good value. A new, properly made compatible pack is more predictable by comparison.

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Inside a Third-Party NP-FZ100: Cells, Protection Board and Control Chip

Open up a third-party NP-FZ100 and there are only four things worth looking at: the cells, the protection board, the communication circuit and the shell. Across the price band that matches our NP-FZ100 at around $17.89 per cell, our lab testing generally finds structure and protection circuitry to be reasonably complete. Where samples separate is cell consistency and solder quality. On usable capacity against the label, the range we typically observe runs from about 90% of the rated figure up to close to the full number, with the occasional sample below that.

One caveat up front: what follows is structure and build quality, not precise per-unit numbers, and no single visual detail should be used to judge whether a cell is good.

Before opening anything: safety and method

  • Don’t do this at home: a lithium pouch or can that is deformed or shorted can heat up and ignite. Read the structure below as public reference and service-level information.
  • Discharge first if you must open one: a full cell carries far more energy into a short.
  • Never puncture, bend or burn a cell: a swollen one stops being used and goes to a recycling point.
  • Opening voids the warranty: everything below comes from samples prepared specifically for this purpose.

Swelling and other safety questions are covered in are third-party camera batteries safe and in our guide to handling a swollen NP-FZ100.

Part one: the cells

The NP-FZ100 is rated 2280mAh / 7.2V / around 16.4Wh. That nominal 7.2V points to the usual two-cells-in-series (2S) layout: two 3.6V nominal cells stacked. In practice you see two formats:

Format Characteristics What to look at
Two cylindrical cells, aluminum or steel can Easier to match, lends itself to standardized packs A dedicated holder, and solder joints that look full
Pouch (polymer) cell Adapts to the shape, uses shell space well Cushioning around it, and no creases at the edges

A few indirect indicators we lean on in our own testing:

  • Usable capacity against the label: under fixed conditions we generally see somewhere in the 90%–100% band.
  • Spread between samples of the same model: the tighter the numbers across several samples run under identical conditions, the better the consistency control.
  • Voltage settling after a full charge: a small drop over time is normal; a fast slide usually means higher self-discharge.
  • Capacity retention after cycling: hard to measure short-term. Judge it by feel after a few months of real use.

To check whether the cell in your hand is honestly rated, see how to spot inflated capacity ratings.

Part two: the protection board (PCM)

The protection board is the small circuit inside the pack that keeps abnormal conditions contained. The parts worth recognizing:

  • Protection IC and MOSFETs: handle overcharge, over-discharge, overcurrent and short circuit.
  • Fuse or resettable protection device: the last physical line of defense under fault current.
  • NTC thermistor: feeds temperature back to the charger or body, which is what cold and overheat protection hang on.
  • Balancing resistors: passive balancing between the two series cells, slowing the drift in voltage between them.

In our experience, mid-priced samples usually include all of the above. Differences show up in component selection, solder quality and whether any insulating separation is present. Packs with no separator, holding cells in place with tape alone, tend to survive drops less well. Worth saying plainly: a protection board reduces risk, it does not remove it, so any claim of zero risk is not credible.

Part three: the communication circuit, or “chip”

To show a percentage on screen, the body has to talk to the cell. On the battery side there is usually a small MCU or a dedicated fuel gauge returning voltage, current and temperature in the format the body expects.

  • With a communication circuit: the body shows a percentage, and the reading is generally usable.
  • Some Sony bodies warn that remaining charge may not display accurately: a routine message with compatible cells. Power is unaffected and shooting continues.
  • “Cannot recognize this battery”: that is a fault. Clean the contacts, try another charger, then go to the seller.
  • Jumpy gauge readings: usually a fuel-gauge calibration issue, often settled by one full charge-and-discharge cycle.

The mechanics of gauge reporting are explained in our chipped versus non-chipped comparison, and error handling is in our unrecognized battery fix.

Part four: shell and structure

  • Material: flame-retardant PC/ABS is typical; the surface should be free of burrs and sink marks.
  • Internal fixing: cells should sit in a holder or on cushions, with no rattle when you shake the pack.
  • Contacts: even plating, no obvious wear after a few dozen insertions.
  • Catch and dimensions: it should go in smoothly without play. Too tight wears the compartment, too loose risks intermittent contact.
  • Seam finish: ultrasonically welded seams are usually tidier, and also the part you should never pry at.

Appearance and actual consistency do not line up one to one. Cleaner build suggests controlled process, but cell quality still needs measured data to confirm.

Turning structure into a buying checklist

  • Clear model, capacity, voltage, Wh and responsible party: the baseline for traceability.
  • Specific protection functions named: overcharge, over-discharge, overcurrent, short circuit — written out, not implied.
  • Warranty term and how to reach someone: worth more than any build description; see the NP-FZ100 warranty page.
  • Buy several from one batch: easier to manage and easier to compare.
  • Pick capacity by need: the practical difference between 2280mAh and 2400mAh is analyzed in 2280mAh versus 2400mAh.

FAQ

Does opening a cell ruin it?

Yes. Once the shell is pried apart, sealing and cell fixing are compromised. Even glued back together, it should not go back into a camera, and it should not fly.

Can I judge quality from the cell brand printed inside?

Only as a hint. One maker’s cells come in different grades and batches, and end performance depends on pack consistency and protection design.

Why do some third-party cells fade noticeably after a while?

Usually limited cycle life in the cells themselves, compounded by deep discharges and hot charging. Holding around 80% capacity after 300–500 cycles is a normal range.

Do our teardown observations apply to every third-party cell?

They do not. Cell sourcing and process vary a lot between suppliers. What is here is a general structural read; any specific model still has to be judged on its labeling and warranty.

Our NP-FZ100 compatible battery is rated 2280mAh / 7.2V / around 16.4Wh, at around $17.89 per cell, around $22.93 for one cell with a charger and around $36.74 for two cells with a charger. For more capacity, the TNP-FZ100 (2400mAh / around 17.3Wh) runs around $39.92 for the two-cell kit. Studios, reviewers and purchasing teams wanting to compare samples side by side can use the wholesale inquiry page for volume pricing and same-batch samples.

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DR-FW50 vs DR-FZ100: Why the Cases Are Not Swappable

Short answer: they are not interchangeable. The DR-FW50 bays are molded to the length, width and thickness of the NP-FW50, and the NP-FZ100 is clearly larger, so it will not fit. The reverse is just as wrong: an FW50 in an FZ100 bay sits loose and the contacts do not line up. These are two independent battery systems with their own matching cases, and there is no universal bay. If you need both, the right answer is two cases, not a workaround.

The question usually comes up during a body upgrade: you shot an A6400, later added an A7 body or an A6600, and now own two battery systems. Can one case cover both? No — but understanding why is more useful than memorizing the conclusion.

The difference starts with the battery

The NP-FW50 is a small battery at 1020mAh / 7.7Wh / 7.2V, shaped fairly flat so it could fit the compact bodies of the A6000 series and the early A7 models. The NP-FZ100 was designed for larger bodies, with capacity and volume a step up and thickness especially obvious.

A charging bay is not just a recess that something drops into. It has three parts that must fit precisely: the guide rails on each side, the spring contacts at the bottom, and the latch above. All three are designed for one specific battery outline. A millimeter off and the contacts no longer press where they should.

So bay compatibility is not a question of “roughly the same size” but of “was this mold cut for this model.” The DR-FW50 answers only for the NP-FW50 series; the DR-FZ100 answers only for the NP-FZ100 series.

Size and bay comparison

Point of comparison DR-FW50 DR-FZ100
Battery supported NP-FW50 series NP-FZ100 series
Battery outline Flatter and narrower Wider and thicker, a size up overall
Bay depth Cut to FW50 thickness Deeper, to take a thicker battery
Contact position Matches FW50 bottom contacts Matches the FZ100 contact layout
Result of mixing FZ100 will not fit, or only goes in at an angle FW50 sits loose and fails to register

The word “angle” in that table deserves its own paragraph. Some people lay an FZ100 diagonally into an FW50 bay so one edge barely touches, and the light flickers on occasionally. That state neither charges the battery nor avoids permanent stress on the contacts at an angle — the worst of both outcomes.

Three consequences of forcing it

  • It will not charge, and you will blame the battery. With the contacts misaligned the case cannot detect the battery, so no light comes on. Plenty of good batteries have been written off as faulty this way.
  • The contacts deform. Repeated angled insertion permanently bends the spring contacts, and even the correct battery will then make poorer contact. This damage is irreversible.
  • The shell and latch take damage. Forcing the lid shut loads the battery casing, which at best scratches and at worst deforms it — and a deformed casing can make poor contact inside the camera.

Of those three, the first is a misdiagnosis and the last two are real damage. Saving the price of one case can cost you a battery plus a case, which is a poor trade.

What to do if you run both systems

  1. Two cases, each independent. The DR-FW50 handles FW50 batteries, the DR-FZ100 handles FZ100, each with its own cable. Do not cross them.
  2. Distinguish them by color or label. A strip of different-colored tape on the outside is enough to tell them apart in low light and avoid a wrong load at midnight.
  3. Mark the batteries too. Prefix FW50 batteries with F and FZ100 with Z, and put a matching note inside the camera’s battery door.
  4. Allocate by body when traveling. Bring the case for the body you are bringing, not both, so you are not carrying dead weight.

If you truly can only bring one case, bring the one for your main body, and top up the other system’s batteries through a direct-charge version such as the YO TNP-FW50, which has its own USB-C port. That is the most practical value of direct charging in a mixed kit.

One last warning: do not count the A6600 as part of the FW50 family. This is the easiest mistake to make. The A6000, A6300, A6400, A5100, ZV-E10, the NEX series, the RX10, and the A7 and A7 II all use the NP-FW50; the A6600 uses the NP-FZ100 and sits outside this system.

Which means “the whole A6000 series uses FW50” is simply false. Before buying a battery, a case or a spare power source, check against the specific model rather than inferring from the series name. For the FZ100 system see the FZ100 category page; for the FW50 case see the DR-FW50 category page.

Note also that the FZ100, being larger in capacity, does not behave identically to the FW50 in cold conditions; there is a separate test record at the NP-FZ100 cold-weather test, but it applies only to the FZ100 and cannot be projected onto the FW50.

FAQ

Can the DR-FW50 charge an FZ100 battery?

No. Both bay size and contact position are wrong, so the battery cannot reach the correct position and the case will not detect it. Forcing it in at an angle risks damaging the contacts.

Can the two cases share a charging cable?

The cable itself is usually shared, as long as the connector type matches and the supply is adequate. Do not run both cases from one splitter at the same time, though; the supply tends to sag and detection becomes unreliable.

What happens if I put an FW50 in an FZ100 case?

The bay is too wide and too deep, so the battery sits loose and cannot press on the contacts; in most cases no light comes on. Even if contact is briefly made, movement will interrupt charging.

Which battery does the A6600 use?

The NP-FZ100. This is the most frequently misreported detail in the lineup — check the model when buying rather than reasoning from “Alpha 6000 series.”

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DR-FW50 Charging Case: LED States, Order and Heat

Short answer: the YO DR-FW50 is a two-bay charging case, not a battery — it holds no charge of its own. Its job is to charge two NP-FW50 series batteries at once and, with the lid closed, to carry them as a storage box. Push each battery into a bay in the correct orientation and connect a 5V supply; the bays are managed independently, the battery loaded first usually finishes first, and once the indicator moves from “charging” to “full” you can take it out. Charging with the lid shut builds a little heat, so open it in summer or during back-to-back fast charges.

First-time buyers often assume it is a case with a battery inside and are surprised to receive an empty shell. So the positioning is worth stating plainly: it is an accessory for an accessory, and it serves batteries you already own. Before buying, count how many batteries you have; with only one, its value is mostly as storage.

The most accurate way to think of it is a battery box with a circuit in it. The shell is hard plastic, the two bays follow the FW50 outline, and each bay floor carries metal contacts and locating pins; the inside of the lid usually has a foam pad so the batteries are held still when it closes. Three sentences cover its boundaries:

  • It is: a two-bay charger, a battery storage box, and a way to keep batteries organized on a trip.
  • It is not: a battery, a power bank, or anything that can power a camera body.
  • It cannot: charge an NP-FZ100 (the FZ100 is larger and will not fit an FW50 bay) or charge a phone.

That distinction matters, because “charging case” invites comparison with a power bank. It needs an external supply to work and stores no energy itself.

Reading the indicator lights

Light colors vary slightly between production batches, but the logic is consistent: one light per bay, using steady, blinking and off to express four things. The table groups them by function; for exact colors, follow the sheet in the box.

Light behavior Meaning What to do
No light after connecting power Bay empty, no battery detected Check that the battery is seated fully and the contacts are clean
Blinking or pulsing steadily Charging Normal; wait
Turns steady That bay is full Remove the battery, or leave it in place
Rapid blinking or an unusual color Battery fault, poor contact, or overheating Remove the battery, inspect the contacts, let it cool and retry

The key to reading the lights is to treat the two bays separately. They are independently managed rather than wired in series, so the left bay can sit steady while the right is still blinking; that is normal and does not indicate a fault. If one battery blinks for hours without going steady, move it to the other bay first — that quickly tells you whether the problem is the battery or the bay.

Charging order across the two bays

There are two common designs: both bays output at once and each proceeds at its own pace, or a primary/secondary arrangement fills the first bay before switching to the second. The DR-FW50 belongs to the independent group, so both bays run together, though differences in starting charge, internal resistance and age mean they finish at different times.

In practice, this order works well:

  1. Put the least-charged battery in the left bay. The left bay is often the primary one, and some designs give it priority on current, so starting with the emptier battery gets you a usable pack sooner.
  2. Load both batteries, then connect power once. Repeated plugging and unplugging makes the control circuit renegotiate and actually slows things down.
  3. Pull either battery as soon as its light goes steady. There is no need to wait for both; before an outing there is often only time to fill one.

If your habit is to plug in at night and collect both in the morning, order is irrelevant — both bays finish before dawn. Order only matters in the case of “two hours until I leave and both batteries are empty.”

Heat: why the closed lid runs warm

Both the batteries and the charging circuit generate heat, and a closed lid traps it in a small space where it escapes slowly through the shell. In winter this is a non-issue; in summer, or when charging two in a row, it is noticeable.

A few practical habits:

  • Charge with the lid open when the room is warm. The lid is mainly for storage and dust protection; leaving it open while charging costs nothing and dissipates heat far better.
  • Do not charge inside bedding, on a sofa, or in a bag pocket. These are the places where heat cannot escape, and where problems are most likely.
  • Unplug if it feels genuinely hot to the touch. Normal charging is warm; if you feel you need to move your hand away, the ventilation is inadequate.
  • Do not charge a battery straight off the camera. A battery coming out of a body is already warm; give it ten minutes or so before it goes into the case.

One clarification: heat during charging is normal physics for lithium batteries, and warm does not mean faulty. The signals to act on are “too hot to hold” and “accompanied by a smell or swelling” — the latter means stop using it immediately.

Everyday use and storage

Storage is the case’s second job. Two batteries and a case are far easier to manage than two batteries loose in a bag: no keys or coins scuffing the shells, and no contacts shorting against metal objects. Closed, it is roughly the size of a cigarette pack and fits a camera bag’s front or side pocket.

For long-term storage, leave the batteries at five or six tenths of charge before they go in, rather than storing them full or empty. On travel and security checks, see the rules for carrying lithium batteries with you (the same rules apply to the FW50). The body compatibility list for the batteries themselves is on the TNP-FW50 category page; if your batteries are the USB-C versions, case charging and direct charging can run in parallel, as described on the NP-FW50 battery page.

FAQ

Does the DR-FW50 include a battery?

No. It is an empty case and you supply the NP-FW50 series batteries. Confirm you already own batteries before buying, because the case cannot be used on its own.

Can it charge one TNP-FW50 and one genuine FW50 at the same time?

Yes. The bays are managed independently, so mixing is fine and each battery’s progress is judged separately. They simply finish at different times because of their different ages.

Can the case charge the FZ100 battery used in the A6600?

No. The FZ100 is larger and will not fit an FW50 bay, and the contact layout differs. The A6600 belongs to a separate battery system.

Is it safe to charge with the lid closed?

Under normal conditions, yes — the case is designed to be used closed. In a hot room, on bedding, or inside a sealed bag, leave the lid open and make sure air can move.