battery balancer for 3 cells but i have only 2 cells, should be ok? - Page 1
Forum section: electronics / beginners

author: danieltronic
author_rank: Newbie
timestamp: November 01, 2017, 06:27:34 am
content: so i have a battery balancer designed for 3 cells. like this onehttps://ae01.alicdn.com/kf/HTB1qHO5NXXXXXXAXpXXq6xXFXXXC/Simple-11-1V-li-ion-font-b-battery-b-font-charger-font-b-3S-b-font.jpgAnd i have a battery pack of 3 cells (11.1v) (https://cdn.instructables.com/FUE/3MAR/IC0VCJR5/FUE3MARIC0VCJR5.MEDIUM.jpg) with 2 set of cables, one cable set for total ouput power, and the other cable set to check each cell state i guess , but i checked the cells and one of them is absolutely dead. if i disconnect t the dead battery and charge them with the balancer, should be ok? should i make any hack to the balancer?

author: Nusa
author_rank: Super Contributor
timestamp: November 01, 2017, 07:14:01 am
content: a) A 2-cell-in-series pack will have a lower output voltage than a 3-cell-in-series pack, so it's not likely to work in the original device or application.b) You should NOT try to charge a 2-cell pack with a 3-cell charger.c) The charger might be modifiable, but given (a), probably not worth it.

author: mikerj
author_rank: Super Contributor
timestamp: November 01, 2017, 11:53:42 am
content: Also completely dead lithium ion cells should not be recharged anyway. If you must then do it outside, but that cell will never perform well again.

author: paulca
author_rank: Super Contributor
timestamp: November 03, 2017, 11:57:57 am
content: I'll second the warnings about charging dead LiPos. However they "can" be recovered, sometimes. The party-line that once a Li* is fully discharged it is dead is not as black and white as often touted.I personally landed an RC glider in a tree. It took me three days to work out how to get it down, all the time it was on running the Rx etc. When I checked the 3s 1100mAh LiPo it read a total of 2.8V open circuit, less than 1V per cell on the balanced reader.I charged it using a balance port only charger on very low current while placing the battery in a metal biscuit tin set on a wooden block (to contain fire and heat in the event it burst).It charged back to 12.6V and continued to function fine. I even capacity tested it and it yielded something close to original spec. It wasn't even bloated.In your case however I would not take or put any load on the main supply cable. Doing so cause the charged cells to over drive the dead cell. I would find a balance port charger (which your charger "looks" like it might be) and try and charge the cells slowly individually. The risk you run is that, that charger has no display or metrics so you can't tell what is happening. Something like an Acculcell would give you volt and current indications as well as individual cell voltages and you would be able to see any problem before it develops into a safety issue.If you are reading 11.1v or higher from the main supply cable, then it may be the balance lead to one cell has disconnected, but the cell is not dead. You might need to measure it under increasing load to really tell. If you are not comfortable stripping the outer wrapper and checking it I would bin it (environmentally friendly!). They are cheap as chips.