Laptop battery controllers - Story of a laptop battery overhaul

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Laptop battery controllers - Story of a laptop battery overhaul

The following text was sent to this Karosium blog page a while ago, before a little bit of make up but it's basically the same:


More or less recently replaced all cells in a ThinkPad 42T4858/42T4814 battery, its inboard smart stupid R2J240 battery management logic blew up the 12AH3 fuse for some reason. At first I successfully made it work and re-calibrate, then left battery and computer sleeping for around 3 months. A few days ago I took the laptop to verify it, noticed it wouldn't boot into Windows with the battery. Started to freak out. Once booted, the battery information tool told me the battery was at “0% charge” despite its voltage reading was well above 11V, and it was charging. I freaked out, thinking something went wrong somehow in my internal assembly. Disassembled the battery again and rebuild it in a more convincing way to me. My cell assembly, however, was not at fault. I just left in a low state of charge and this was the reason the system wouldn't boot on battery power. Nevertheless, upon reassembly I did not soldered the logic board terminals secuentially or whatever and I triggered the chip's fault flag (reason for the blown up fuse, I think). The laptop refused to boot on battery power and once it did the battery software reported a dead battery. Crying
Sorry for the drama.
Question is, ¿besides replacing the fuse what are my choices with regards to the R2J240?
I contacted the guy at Battery EEPROM Works ( to ask for a solution but after telling him I just needed to fix a single battery all he had to say (literally) was “Нщн”. Flat Stare
Thanks in any case.


If anyone here has something to say which could be of help please do so. Of course the carelessness of the Battery EEPROM Works guy is gotta have its consequences, and I am not going to blame or judge him. It sort of reeks the same secrecy and closed standards crap the battery OEMs do customizing TI controllers.

And I could, I could start name-calling and no shite in this world would escape, but I'll leave this for the privacy of my room. I've learned there's no actual good reason for it, at least here.


Cheers Wink 

The Light Innocent I am