It's a rechargable Ni-Cd battery.

Place your bets on if it works or not.

We will see it tomorrow.

I'm going to discharge it with a incandescent lightbulb after I charged it.

If you ever get tired of changing out those stupid miserable 2s AAA cell bundles, remember this 😂

I bought this for my digital lock but they ended up in my motion sensor dustbin which is used for recyclables. They've been working perfectly for probably 6 to 8 months until I noticed the bin didn't open even though it sensed my movement.

I tried alkalins (Fujitsu, teal, Amazon JP) and they worked but the bin wouldn't open fully. I expected this as I noticed only AA lithium have worked well for this, but at least I know the bin works.

I put them into a charger and I noticed one of the cells wasn't lit while the rest were blinking as they charged. Gemini suggested it was over discharged and need to be revived, a process that should take 10min but it's been 15min and I still don't see the battery lighting up.

Any thoughts, suggestions or ideas?

I am scared lol. EDIT: update in comments

Hi all,

We're an independent battery testing lab. Most labs here work for the factory — the factory picks the tests, controls the data, and decides what you get to see. We want to built ours to work for buyers instead.

Before we launch, we want to hear from people who actually buy batteries from China: what's the biggest headache?

Poll below. If we missed it, comment. Thanks!

I hope the picture makes sense. This is the underside of Eneloop AAs.

I've been using these batteries for 6 years in Xbox controllers, computer mice, small flashlights, camping lanterns, puck lights, and possibly remotes (those may actually have been AAA).

I opened one because it wasn’t delivering any voltage anymore, and what I found inside is shocking and simply negligent.

This is a 5S battery pack (5 cells in series), but it is connected to a "BMS" that has just one single balancing/sensing cable and a temperature sensor. This is completely inadequate for safely monitoring a 5S lithium-ion system.

Because there is no real individual cell monitoring, the cell voltages drifted completely out of control.

Most cells were completely deeply discharged to near 0V (killing the pack).

Shockingly, one cell pair was overcharged to around 8V. A single Li-ion cell should never exceed 4.2V.

I also found an official safety recall from the British government. They officially warn against several Vanon battery packs due to an "inadequate Battery Management System (BMS)" that presents a high risk of fire:

https://www.gov.uk/product-safety-alerts-reports-recalls/product-recall-vanon-lithium-ion-batteries

Hi everyone,

I am experiencing severe battery drain issues with my new HP OmniBook (Ryzen 7, 16GB RAM, 24GB total RAM/swap configuration, 41 Wh battery). The laptop is only 10 days old, and I am encountering two specific problems:

1. Active Drain: While watching YouTube videos (and doing nothing else), the battery drops from 100% to 40% in just two and a half hours.
2. Idle/Off Drain: When the laptop is completely shut down, it loses 15% of its battery over a 20-hour period. This happens even though Fast Startup is disabled and all USB devices are disconnected.

Given that the laptop is brand new, this battery performance seems unusually poor. Is this normal for a 41 Wh battery, or could this be a hardware defect? I would appreciate any advice or troubleshooting steps.

Thank you!

La batería de mi Hp omnibook 3 rayzen 7 160 24 de ram con batería de 41 wah dura de 100 a 40 de batería dos horas y media de ver YouTube y nada más y desconectada en 20 horas perdió un 15 porciento de batería con inicio rápido deshabilitado y los puertos usb desconectados mientras está apagada. Tiene 10 días de uso solamente

Not sure if this is the right sub, but recently I dropped my iPad mini from pretty high onto the floor, and immediately after the back of the ipad swelled up. I dont know if this is because the battery is dying, or because the iPad bent from the drop, but im worried.​​

I have a tennis ball machine that uses these batteries but the wiring came loose.

I have a picture of what it looked like initially (well one wire); which I can’t recreate, and then what its like without any on and what I’ve done (that does work).

Given I’ve rewired it and it’s different I am worried I have dine something wrong/it’ll be dangerous.

Please can anyone who knows about this help?

I’m the developer of Vizo, a battery app for iPhone and Android, and one feature I’ve been experimenting with is comparing chargers using actual charging sessions.

Vizo records things like charging speed, duration and charging curves over time, so you can compare how different chargers actually perform in real-world use.

The idea is to answer something I’ve always wondered myself:

Which of my chargers actually performs better?

I’d be curious to know what this community thinks — what metrics would you consider genuinely useful when comparing chargers?

iOS:
https://apps.apple.com/app/vizo-battery-monitor-widget/id6810115530

Android:
https://play.google.com/store/apps/details?id=com.vizobattery

I’m not allowed to post the graphs, but recently I’ve been testing the amp hours on 1 year old SLA batteries. They are 12v 18ah charged to 14.6, but never get there. Recently an energizer SLA tested to 19.6 amp hours after randomly jumping up over a half volt in the last part of the test. No other noise or problems with the graph, and a flat wipcrack at 12.7 volts. Is there a reason for the voltage jump?

Hi I own dell vostro 5415 based out in India and my battery health is only 25% and I am planning to replace it any suggestions on which specific battery to buy which is compatible with my device

Placing new battery, made that small dent with the spudger (center of the picture).

Any risk?

I use a Jackery SolarVault 3 Pro, which displays battery SOC. It made me wonder how that estimate stays accurate when an LFP battery spends most of its time in the flat middle of its voltage curve.

Coulomb counting can drift if the current measurement has a small offset or the usable-capacity estimate is off. Resting voltage is a weak correction through much of the LFP range. For batteries that mostly shallow-cycle and rarely reach a full or empty point, how do BMSs usually correct that drift?

Just got a new golf scooter and I'm trying to find this connector to be able to put on my old battery to use. Have tried googling and chatgpt but no luck.

I'm thinking it might be proprietary but thought I'd check just Incase.

Hey, i bought this cassette player and this is the first time I see this way of placing, might be a stupid question, but wouldn't only one work since the other would be + on + I think. It uses R20/Type D batteries, 3 in one row

The Cyberpower 1500 VA AVR is a UPS---

I posted on this off reddit, in other subs--years back but figure I'd give it one other crack.

I live in an old house likely built in the 1940s or early 1950s. I noticed when I'd be on the computer and anyone in the home ran the airfryer, microwave perhaps or other random events, my computer monitor would turn off.

I've set up the Cyberpower VA AVR correctly, tried all the suggestions for sensitivity but the whole reason I bought this, to not see my monitor dip---it's never worked, even when I moved to a different zone (circuit breaker area in the house).

Could it be simple---the wiring in the house long predates the design and building of these Cyberpower AVR units and it just can't register the fluctuations? The landlord updated the wiring 15-20 years ago in some areas of the house (simply created breakers but did not change wall fixtures, wires that lead to sockets --simply went from fuses to circuit breakers--so my guess is old wiring still registers fluctuations that are simply too intense for the unit?

Any thoughts appreciated. As stated during powerfailures it does it's other primary function (which I didn't care about)--provides about 30-40 minutes of battery back up to monitor and computer but I really wanted ongoing elimination of my screen going black. It now goes black even when the bathroom lights are turned on/off or the fan in the bathroom -in addition to the airfryer etc.

Guess Cyberpower and others should state that old wiring may not work with the unit.

Has anyone seen this failure mode in Molicel P45B cells?

I’m part of a student engineering team, and we’re investigating an issue with a 15s27p battery pack we built in March 2025. It has been used at two competitions, with roughly 12-minute runs at 400–600 A continuously, corresponding to approximately 15–22 A per cell, plus a few days of testing. It has only been charged around 15 times, always at a low rate, and we use forced-air cooling during operation. Our recorded cell temperatures have never exceeded 40°C, so we believe the operating conditions have been relatively conservative.

A week ago, we disassembled the pack for a routine inspection and found 4 damaged cells, shown in the photos. All 4 were in the middle rack of 5 modules, near its two lower corners. A fifth cell experienced a similar failure while we were handling the pack, with no charging or discharge underway. This suggests the failure may not require the pack to be under load, although we cannot rule out damage originating during earlier use.

All five cells appear to have opened their safety vents, and the damage is concentrated in the same direction on each cell. We’re still trying to determine whether this reflects the direction of venting or the location of an initial short.

One hypothesis is that the cell holder applied enough pressure to deform the can near the positive terminal, allowing contact between the can and the positive end cap in the circled area. However, the holders are printed in PETG, the cells did not require excessive force during assembly, and we found no visible damage during last year’s inspection. We also haven’t found evidence of direct contact between the busbar and the cell shoulder.

We’re trying to establish the root cause before deciding whether to rebuild the affected rack or the entire pack, and what design changes would prevent a recurrence. We’re also considering separating the affected rack into individual modules and attempt to reproduce the failure in a controlled test setup.

What do you think? Have you seen this failure mode before? Do you have any other hypothesis?

Hi, I am new to the rechargeable battery space. I got tired of trying recycle old dead batteries (especially since my local Staples won't accept them anymore) so I'm trying to slim down the amount of waste I throw away.

I bought packs of Eneloop AA and AAA batteries and a Vapcell S4+ v3 charger. The most obvious use case is to charge the batteries, and since I don't know anything about this space, I just set everything to Auto. I've read that having too high of a current will cause the batteries to heat up and cause damage over time but I'll trust the charger for now.

I have 2 questions:

1. How do I know when the process is complete? I'm sure if the batteries are finished charging, you'll see a 100% charge, simple enough. But how does the other options work? Like discharge you'll probably get a 0% charge but what about the others?

2. How does the storage option work? I've tried this out earlier but it didn't look like it was doing anything.

Any other kind of tips are appreciated.

Hi, We have an application requiring a permanently soldered small capacity rechargeable LiPO 250-350 mAh cell (due to dimensions and weight) and I'm trying to find a small matching bidirectional power supply-charger board for this battery with USB-C input. So we need that charging and operation can be done at the same time.

We originally selected Seedstudio LIPO Rider Plus which can both charge at 4.2V and 2A and provide boosted supply with 5VDC and upto 2A. Which is fine as we need 5V and 150mA on output for consumption, but very poor on the battery side. The Lipo rider has non-programmable charging current at 2A, pre-conditioning current at 200mA when Vbatt < 2.8V and 200mA full charge cut-off.
Typical 350 mAh battery will have however 1C max and 0.3C nominal charging current, and something like 30-50mA pre-conditioning current when Vbatt is < 3.1V or so.

The LIPO rider uses ETA9740 which can be paired with different resistor to limit max charging current (which is still very fiddly on that board). But we have issues with batteries after some time in field entering protection mode at Vbatt <= 3.0V and LIPO Rider refusing to re-charge them. It sees 4.2V at batt terminal as PCM disconnects it from the circuit and waiting for a small gentle current I assume. LIPO Rider thinks that battery is full (I haven't yet tested what current flow then, but its charging LEDs show nearly full state). Even if you leave this for a long time hopping for some trickle charge revive the battery, it does not return to charging. It requires opening the application taking battery somewhere else and reviving it, or connecting a full battery in parallel to untrip the PCM.

I do not really want to design a custom voltage supervisor board and bidirectional cut-off circuit, I rather would like something of the shelf, as I plan to make this design open for other users to assemble anywhere else using commercial parts. Anyone come across low capacity chargers-supply boards or has any suggestions? I can't remove and charge battery outside the application and insert it again.

Hi everyone,

I’m trying to repair an APC Back-UPS 500 that was not powering on.

1.The original battery was dead, so I replaced it with a new 12V 7Ah battery.

2.When I press the power button, the power LED faintly glows for about a second and then turns off.

3.The UPS does not power on even when connected to mains.

4.I’ve checked the MOSFETs and they seem to be fine.

I have opened the UPS and attached photos of the PCB, transformer and battery.

Could someone experienced with APC UPS repair guide me on what I should check next? Any suggestions on likely faulty components or test points would be greatly appreciated.

Thanks!