Short answer: the Sony NP-FW50 is a small 7.2V pack rated 1020mAh, about 7.3Wh. It arrived with the NEX series in 2010 and stayed in service through the A6400, A6500 and ZV-E10, making it the most widely fitted battery Sony has made. It shares nothing with the NP-FZ100: the shape, thickness and contact layout all differ, so the two are completely incompatible. The FZ100 is 7.2V, 2280mAh, about 16.4Wh — more than twice the energy. The rule is simple enough: an A6000-series body, a first- or second-generation A7, or any NEX takes an FW50; an A6600, an A7 III or anything later takes an FZ100.
1. Which bodies take the NP-FW50
The FW50 had a long life, spanning Sony’s whole transition from NEX to E-mount mirrorless. The same pack works in a 2010 NEX-5 and a 2019 A6400, which is why so many are still in circulation. The main bodies are listed by product line below; the label inside the battery bay is always the final word.
| Product line | Main bodies | Note |
|---|---|---|
| NEX series | NEX-3, NEX-5, NEX-5N/5R/5T, NEX-6, NEX-7, NEX-3N, NEX-F3 | The first bodies to use the FW50 |
| A5000 / A6000 series | A3000, A5000, A5100, A6000, A6100, A6300, A6400, A6500 | The A6600 is the exception and uses the NP-FZ100 |
| A7 first and second generation | A7, A7R, A7S, A7 II, A7R II, A7S II | From the A7 III onward the line moved to the NP-FZ100 |
| ZV series | ZV-E10 | The ZV-E10 II moved to the NP-FZ100 |
| RX and others | RX10, RX10 II, RX10 III, RX10 IV, QX1 | The long-zoom RX bodies also take the FW50 |
The easy trap in that list is the A6600. The name puts it in the A6000 family, but its bay is built to FZ100 dimensions and an FW50 will not go in. Likewise the A7 III, A7R III, A7C and A6700 all use the FZ100. Any A7 marked third generation or later can be ruled out for the FW50 straight away.
2. What 7.3Wh actually means: capacity and real runtime
7.3Wh looks small today. For scale, a mainstream phone battery is roughly 15-20Wh, so an FW50 holds less energy than a phone. In camera terms, that translates to the following:
- Official CIPA figures: about 410 shots on the A6400 (LCD), about 400 on the A6300, about 360 on the A6000 and about 350 on the A6500. These are lab cycle-test values.
- Real shooting: most owners land between 250 and 350 frames, with a clear drop outdoors in winter, when reviewing constantly, or when transferring over Wi-Fi.
- Video: typically 60-80 minutes of continuous 1080p; 4K usually stops after 20-30 minutes because of body heat rather than charge.
Put another way, the FW50 is a pack that is adequate but needs backup. If a day runs past 300 frames, or you are covering a wedding, an event or travel where recharging is impossible, two to three packs is the normal configuration rather than over-preparation.
3. NP-FW50 versus NP-FZ100
These two get compared constantly because they stand for Sony’s two mirrorless eras. The difference is not only capacity but the whole power architecture of the bodies.
| Item | NP-FW50 | NP-FZ100 |
|---|---|---|
| Nominal voltage | 7.2V | 7.2V |
| Nominal capacity | 1020mAh | 2280mAh |
| Energy | About 7.3Wh | About 16.4Wh |
| Size and thickness | Thinner and smaller | Markedly thicker, close to double |
| Interchangeability | None. Bay dimensions and contact positions differ, so neither will fit or adapt to the other | |
| Typical runtime difference | Baseline | More than twice the FW50 |
Worth noting is that the FZ100 does not just mean a few hundred more frames. Bodies from the A7 III onward support USB power and higher output, and only a large pack can sustain 4K long takes, dual-card writing and high-refresh finders. Conversely, FW50 bodies are mostly earlier designs with more modest feature sets, so 7.3Wh was not especially tight on that hardware.
If your body already takes an FZ100, the site’s NP-FZ100 section goes deeper on capacity, cold-weather behaviour and buying advice; accessories and backup plans for FW50 bodies are gathered in the NP-FW50 category.
4. Originals, third-party packs and what to look for
The FW50 is one of the most counterfeited Sony packs, for obvious reasons: a huge installed base, a long production life and a low unit price. A genuine pack typically costs several times a compatible one, and the real capacity gap is nothing like the price gap. Work through the following before deciding.
- Confirm the body first: check the table above and be sure it is FW50 rather than FZ100 or BX1. Get this wrong and everything after it is wrong.
- Check whether the rating is honest: a reputable third party quotes around 7.2V / 1020mAh, not “3000mAh”, a number that physically will not fit.
- Check for protection circuitry and a temperature sensor: the body reads temperature through the third contact, and a pack missing that NTC can trigger errors during long summer recordings.
- Check charger compatibility: the FW50 uses a dedicated dock charger, not a universal clamp charger. Most third-party packs work with the original charger, but take a little longer to fill.
- Match the count to the workload: one original plus one spare covers light shooting; heavy work wants three from the same batch, so mixing old and new does not make runtime swing between long and short.
The YO FW50 sits in the middle of the performance and price range, with ratings and protection circuitry that are properly specified — a sensible supplement to originals rather than a replacement for all of them. Watch the production batch when buying: packs from the same batch have closer internal resistance and give a more linear gauge when mixed.
One last warning: the FW50 has been discontinued for years, and a fair share of “new original” stock on the market is pulled from cameras or refurbished old inventory. If the price is implausibly low, treat it as a third-party pack and do not pay extra for the word original.
FAQ
Will an NP-FW50 work in an A7 III?
No. The A7 III and later A7 bodies (A7R III, A7 IV, A7C and so on) use the NP-FZ100, with different bay dimensions and contact positions. An FW50 will not fit and there is no adapter that makes it work. The A7 II and the earlier first- and second-generation bodies are the ones that take the FW50.
How big is the runtime difference between FW50 and FZ100?
By rated energy, the FZ100’s 16.4Wh is roughly 2.2 times the FW50’s 7.3Wh. In practice the official CIPA shot counts for an A7 III and an A7 II differ by a similar factor, but the bodies do different things, so it does not scale neatly onto every camera.
Will an older camera have compatibility problems with a third-party FW50?
Most NEX and early A6000-series bodies work fine with third-party packs, though the gauge may be less linear than with an original and can shut down suddenly while still showing 20%. The newer A6400 and A6500 are stricter about battery communication, so favour models that explicitly state support for those two bodies.
Does an FW50 degrade if left unused for a long time?
Yes. For long storage, keep a lithium-ion pack at 40-60% and top it up every three to six months. Storing it flat for a long period can take the voltage below the protection board’s threshold, at which point the charger simply refuses it. Never recharge a pack that has swollen or deformed; the handling guidance is covered in the older-battery section of the FW50 category.