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  • Posts: 1
  • Registered: ‎04-03-2019
  • Location: DK
  • Views: 106
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L12M4P62 Battery controller repair

2019-04-03, 7:57 AM

Hi folks,


First of all, if I'm not allowed to post this in here, just let me know and I will remove it. (Or an admin can remove it, no problem)


Basic info:

  • Lenovo U430 Touch
  • Bought: 2013
  • Battery: Stock L12M4P62 (usually went about 4-6 hours on a full charge, event after 6 years of usage)
  • Warrenty: Hell naw
  • If you need any other info, let me know and I will post it (within reason of course).


Okay so here is the story, I casually went from my grouproom at the university, where my laptop was plugged in for regular charging, but when I arrived at the classroom, the computer wouldn't boot without external power. So I naturally went back after the lecture to check the battery status, while the computer was plugged in. It was not showing any errors, but instead it showed a fully charged battery.


So I took out the battery and measured accross P+ and P-, absolutely no voltage. I would expect somewhere arround 7.6-8.2 Volts, since the battery was charged. While at this step I also meassured all combinations of pins on the connector... Nothing.


This led me to open the battery and check for faulty soldering or a wire that had disconnected. As expected the battery looked fine inside, no loose solderpads and all the individual cells were charged to 3.98 Volts. The battery controller had no burnt areas or anything out of the ordinary. Except of course the usual "Oh we don't actually need this cap right here", of which there were approximatly 10 or so. The print was also missing two IC's, but I don't think these are the cause of death. I also checked if the fuse had blown but it still works.


The problem is that the silkscreen stopped me dead in my tracks right here. I am not able to follow the layout of the copper traces between components, so I am basicly searching in the dark. I mean I could spend the night mapping all pins to eachother, but I'd rather not.


These finds all lead me to believe that the battery charge controller has died, and since I study electronics I thought I might be able to fix it. I mean it could be as simple as a dead capacitor, which I have available in almost any size and capacitance.


So what exactly am i asking for...?

Well a schematic of the battery controller would be nice, but if this is not available (I've been googling for about an hour with no luck, and I get why lenovo doesn't publish it themselves.) I would very much just like some help figuring out which part has died so I can replace it. I don't like spending 100$ on a battery if I can fix it myself.


TLDR: Windows sees battery is charged, battery does not output voltage, I want to fix, plz help.


Best regards,

Kristoffer "de_rush" Derosche

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