Thinkpad Li-ion battery recelling - Page 1
Forum section: electronics / repair

author: steve30
author_rank: Frequent Contributor
timestamp: April 30, 2017, 09:50:07 pm
content: I was recently given an IBM ThinkPad A31. Its a really nice machine, but the battery is dead.I removed the original 18650 cells, and put some new ones in, and made sure that it is all wired up correctly. However, no voltage is present on the output of the protection/controller circuit. I also cannot charge the battery through the protection/controller circuit.There's no issue with the cells as I can charge them by connecting a PSU directly to the cells (bypassing the controller circuit).Does anyone know why this is? Is there anything I can do to 'revive' the controller circuit?I've read lots of web pages about laptop packs and tried connecting just about every combination of pins but with no sucess. There is also the possibility that the controller circuit has 'forgotten' its settings as a result of the power loss. In the case of this battery, the original cells were long dead, so if this was the case, it would have lost its memory long before I dismantled it.The other possibility I can think of is that I might have killed a component on the controller circuit.The controller isn't entirely dead though, as it will communicate with the computer when plugged in, as can be seen in the screenshots.Any ideas are welcome.Thanks.steve30

author: Nusa
author_rank: Super Contributor
timestamp: May 01, 2017, 12:30:18 am
content: Have you tried charging the original cells to determine their health? It's possible the original failure was in the charging electronics, not the batteries.

author: SeanB
author_rank: Super Contributor
timestamp: May 01, 2017, 09:11:54 am
content: Battery controller on the cells probably operated the kill fuse to disconnect the cells when they finally died, or one went below the minimum voltage, so the pack did not catch fire when charged again.

author: steve30
author_rank: Frequent Contributor
timestamp: May 01, 2017, 11:53:50 am
content: Thanks for the replies.Of the original cells, one pair was good, and the other two pairs were bad.

author: stj
author_rank: Super Contributor
timestamp: May 01, 2017, 12:23:55 pm
content: there is software that can read & write the config to most battery controllers over the serial bus, but i think you have to pay for it.there was a free version that could only read.

author: steve30
author_rank: Frequent Contributor
timestamp: May 01, 2017, 01:47:03 pm
content: As an experiment I tried to bypass the protection circuit and connected a wire link from the positive end of the cells to the connector. (Don't do this and leave it unattended).I'm pleased to say this powers the laptop fine. Its even managing to measure the current. The computer refuses to charge the battery though.I wonder if I could substitute in a different controller or protection circuit. I think this might require some experimentation

author: Rasz
author_rank: Super Contributor
timestamp: May 01, 2017, 02:17:58 pm
content: no need, just look at the pcb for controllerm37516 bq80201 bq8030 BQ8011 ?make an i2c interface and play with SBWorkshop or AccPlus