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
- Acknowledge it and go straight into shooting, first confirming that the shutter, autofocus and playback all behave normally.
- Watch the charge indication. If it falls smoothly, decoding is essentially matching and the pack is fine to use.
- If the gauge jumps badly, try the pack in a second body to separate a pack problem from a firmware problem in that camera.
- 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.