Battery circuit ID help - Page 1
Forum section: electronics / beginners

author: rthorntn
author_rank: Frequent Contributor
timestamp: August 17, 2024, 08:04:47 am
content: Hi,I have this wonderful Neeo remote, it's 7yo, it's been in storage for a year or so.I think the battery is causing issues, it turns on for a few seconds and that's it.It's dimensions are in its code, 4mm thick, 42mm wide and 65mm tall, 65mm including the PCB taped on to it, it's 60mm without.Under the microscope I see two 8205S MOSFET, 202R, G3JE (SL8261D-G3JE battery IC), Cap, 471R, so they have welded a charger PCB on to the battery terminals?I'm thinking of making a new back and using proper cylindrical cells (something like a 14500) that I can take out and charge.Just trying to figure out if there is any other functions in this PCB (like a 5V boost) that will trip me up?Thanks.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 17, 2024, 08:30:34 am
content: Leave it to charge with its normal charger. Beware that when the voltage of the raw cell is too low, it may take many minutes before the battery starts to take charge. Be patient and let it connected to its charger at least for an hour or so. Even if apparently doesn't charge, just let it there connected to the charger. If after letting it connected for a couple of hours the battery still doesn't charge, maybe the raw Li-ion cell is dead.When a Li-ion battery dies, usually the protection circuit outlives the raw cell. So far I have encounter a few times unrecoverable Li-ion batteries. It was always because of the raw Li-ion cell dies, but never found any with the protection circuit defective.What's the voltage on the raw cell, measured at the two wide metal tabs (before the protection electronic)?

author: rthorntn
author_rank: Frequent Contributor
timestamp: August 17, 2024, 08:37:12 am
content: Thanks, yes, I left it on charge for hours.The battery is reading 4V but I think its losing charge while disconnected, I checked it an hour ago and it was close to 4.1V.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 17, 2024, 08:48:33 am
content: That looks like a charged battery.I would try connected a LED + resistor, or some other consumer of no more than 100mA connected directly to the raw cell tabs, and see if it can power the LED for at least some minutes. If yes, make the same test at the connector, to see if the protection board is OK (thinking maybe the defective one is the remote, not the battery).In case the raw cell is still good but the protection PCB is dead, the protection alone can be bought separately from the Aliexpress/Amazon/etc. Search for Li-Ion protection board, or circuit. It only matters the capacity of the battery and the size. The functions of single cell Li-ion protections are pretty standard, doesn't matter much what IC is used to implement that, as long as the protection circuit was designed for a battery of about the same Ah.Same for the raw cell, can be bought separately. Or just buy any ready made Li-Ion (with protection board already included) that can fit inside the remote.

author: rthorntn
author_rank: Frequent Contributor
timestamp: August 17, 2024, 09:16:49 am
content: Thanks, I'll try that.