Beware of RavPower NP-FW50 batteriesI purchased 2 2-packs of these at the end of September. Two of the 4 batteries refused to charge straight out of the box. Over Thanksgiving, a third battery swelled inside my camera body, forcing me to pry it out with a metal tool. I used the battery fewer than 5 times before it swelled. I never put it under stress. No extreme temperatures. Just casual photography.I contacted the company and explained. Told them I’ve lost faith in their product and want a refund. Told them I don’t want to risk damaging my camera from using their battery. They said that since it’s past 30 days, they can only offer a replacement.TL/DR: RavPower dba Sunvalley Brands batteries have a horrible track record and might break your camera.

I bought a couple of them in November 2019 and don't have swollen battery issues. But they're terrible with holding charge and when in use they drain a lot faster than the Sony batteries.

There is information:In June 2021 Amazon removed the Sunvalley brands RavPower, TaoTroncs and Vava from its platform....https://en.wikipedia.org/wiki/Sunvalley_GroupI purchased the Model: RP-PB056BSPF kit from Aliexpress in December 2021. From the seller RAVPowerOfficialflagship Store. Then the item ran out of stock at that seller and did not show up later. RAVPOWER NP-FW50 batteries have some sort of laser-engraved numerical code on the end opposite the contact strip. On the back of the charging adapter is engraved serial number as on the batteries 03255421104. Battery capacity compared to the battery from the kit was RAVPOWER NP-FW50 ≈ 68%. Battery RAVPOWER NP-FW50 #11 cross section 18.40 mm December 2021, after one year 18.60 mm RAVPOWER NP-FW50 #12 battery 18.45 mm section December 2021 after one year19.00 mm Battery compartment width on ILCE-6100 = 19.17 mm The SONY NP-FW50 battery from the Sony α ILCE-6100 kit retains its size in two years without change. Thanks for reminding me. The cross sectional dimensions of the batteries should be checked periodically.

I’ve used a pair and a charger for about two years with my A6400. I don’t have an original battery from Sony. After about two years, one of the batteries became hard to remove from the camera. Before this occurred, I was satisfied with the performance.

I used them for a couple of years and some of them started to swell, and one become unusable (the camera did not recognize it anymore). So it was working fine for me while it lasted. Then I saw a youtube video where a girl managed to short 2-3 Sony cameras with a single faulty third party battery. Then I decided to only use Sony branded batteries as it does not worth loosing my camera over some small savings on the battery price.

Had one of two swell a bit, but just had to pull a bit.  I will not use that one again.

RAVPOWER NP-FW50 No. 11 section 18.40 mm 24.12.2021 Battery RAVPOWER NP-FW50 No. 12 section 18.45 mm 24.12.2021 Swelled over the allowable cross section of 19.17mm on the ILCE-6100 after 13 months.Now after recharging on 03.02.2023 steel 19.40mm 19.20mm Battery compartment width on ILCE-6000 = 19.40mm still fits there. Wink Wink Or go with the Sony NEX-C3K Could certainly go in the battery grip, but I don't use one.Translated with www.DeepL.com/Translator (free version)

You get what you pay for with batteries. I'm frugal (sometimes to a fault), but long, long ago I decided to stop being penny wise and pound foolish, and now I pretty much only buy OEM batteries for all my devices.Unfortunately there doesn't seem to be any mid-priced yet high quality and consistent battery brands. It's either expensive OEM or cheap junk.

I got extra batteries from B&H at the same time when we bought the camera for work, Wasabi needed recharging much faster than original Sony, but didn't get stuck in the battery compartment. Then I got neewer batteries about a year ago for home use based on reviews found on Google search, purchased on Amazon. I probably used the for a total of 10 times, une got stuck, and they didn't hold charge as Sony, from the beginning. Still, it's ridiculous how expensive are Sony batteries.

JustinVP wrote:You get what you pay for with batteries. I'm frugal (sometimes to a fault), but long, long ago I decided to stop being penny wise and pound foolish, and now I pretty much only buy OEM batteries for all my devices.Unfortunately there doesn't seem to be any mid-priced yet high quality and consistent battery brands. It's either expensive OEM or cheap junk.What's especially saddening is that in many cases, the cells themselves are probably good.The problem is that any lithium pack that has more than 1 cell in series (Sony NP-FW50 and FZ100 are both 2S configurations) need cell balancing. Otherwise, any mismatches between cells cause them to slowly drift in charge state, such that one cell fully charges long before the other one. This leads to that cell getting overcharged - hello swelling!For RC lipo packs, this is never a problem because the balancing circuitry is in the charger itself, the pack just brings out balance leads. So el-cheapo lipo packs are usually just fine. But for these packs - that third terminal is NOT a balance lead. It's a digital I/O pin - thus the pack must balance cells internally.Multiple teardowns of third-party batteries have all found the same thing - third-party packs lack balancing circuitry.Low-quality BMS is also why these packs frequently start tripping errors in many Sony bodies.  Other things I've seen people report are stuff like missing temperature sensors (BMS reports a hardcoded temperature), etc.

Is there a write-up or link to explain how Sony incorporates in-pack balancing?Early on, I had been concerned about using third party "two pin" chargers on Sony batteries till I found that the third terminal is not really between the cells as it is on my drone batteries.Thanks!

Entropy512 wrote:JustinVP wrote:You get what you pay for with batteries. I'm frugal (sometimes to a fault), but long, long ago I decided to stop being penny wise and pound foolish, and now I pretty much only buy OEM batteries for all my devices.Unfortunately there doesn't seem to be any mid-priced yet high quality and consistent battery brands. It's either expensive OEM or cheap junk.What's especially saddening is that in many cases, the cells themselves are probably good.The problem is that any lithium pack that has more than 1 cell in series (Sony NP-FW50 and FZ100 are both 2S configurations) need cell balancing. Otherwise, any mismatches between cells cause them to slowly drift in charge state, such that one cell fully charges long before the other one. This leads to that cell getting overcharged - hello swelling!For RC lipo packs, this is never a problem because the balancing circuitry is in the charger itself, the pack just brings out balance leads. So el-cheapo lipo packs are usually just fine. But for these packs - that third terminal is NOT a balance lead. It's a digital I/O pin - thus the pack must balance cells internally.Multiple teardowns of third-party batteries have all found the same thing - third-party packs lack balancing circuitry.Low-quality BMS is also why these packs frequently start tripping errors in many Sony bodies. Other things I've seen people report are stuff like missing temperature sensors (BMS reports a hardcoded temperature), etc.This is very interesting from an educational point of view. Now the usual arithmetic. The SONY NP-FW50 battery is purchased at B&H for $53.95 It takes 6 years before it swells up. One year of service is approximately $9 Set Model: RP-PB056BSPF cost $23.33 One battery minus the charger (RAVPOWER DC Dual Battery Charger) costs $7.82 for one year. The original SONY NP-FW50 is a better choice, but if you can't buy it or you're not sure it's authentic, you have no choice but to go with a third party.Translated with www.DeepL.com/Translator (free version)

missingendpoint wrote:Is there a write-up or link to explain how Sony incorporates in-pack balancing?Early on, I had been concerned about using third party "two pin" chargers on Sony batteries till I found that the third terminal is not really between the cells as it is on my drone batteries.Thanks!No real writeup/explanation, other than user matttelz here doing some teardowns and measuring cell voltages - every third-party pack he's checked came unbalanced from the factory and seemed to have "simpler" circuitry than a factory pack.  He tore down an official NP-FW50 and found the cells to be still balanced after a few years of service.Similarly, not much is known about that center pin other than it's a digital I/O interface, unfortunately the IC that talks to it on the camera side is clearly a custom part as Googling it results in no information for the part itself, just unrelated parts with similar numbers.  You can get schematics of older E-Mount Sonys online, search for "NEX-3 level 3 service manual" (or was it level 4?  or was it a NEX-5?) - I've found at least two detailed service manuals for older Sonys on elektrotanya.com

dgsjsj wrote:RAVPOWER NP-FW50 No. 11 section 18.40 mm 24.12.2021 Battery RAVPOWER NP-FW50 No. 12 section 18.45 mm 24.12.2021 Swelled over the allowable cross section of 19.17mm on the ILCE-6100 after 13 months.Now after recharging on 03.02.2023 steel 19.40mm 19.20mm Battery compartment width on ILCE-6000 = 19.40mm still fits there. Wink Wink Or go with the Sony NEX-C3K Could certainly go in the battery grip, but I don't use one.Translated with www.DeepL.com/Translator (free version)I found a temporary solution for the RAVPOWER NP-FW50 batteries, which increased in cross-section. I peeled off the paper labels neatly. On a flat surface I put abrasive water-resistant paper T44X P400. I polished the two planes a bit. Battery No. 11 swollen to 19.4 mm grinded to a cross-section of 18.5 mm Battery No. 12 swollen to 19.2 mm grinded to a cross section of 18.6 mm I'll see how long you can use these batteries until the next dangerous increase in cross-section. Their energy capacity is still suitable for use.

I have several third party batteries including those and NONE of them are anywhere near as good as the Sony original battery.  I haven't had the swelling problem so far, but their ability to hold a charge is ridiculous.  I have 2 Sony batteries that came with my a6000 and my a500 that last 3-4 times as long and are older than the 3rd party batteries.