Why I hate batteries

Fujitsu Laptop Battery

Today it’s been a bad day, not because it’s rainy, but because a laptop battery died on me.

For “died on me” I mean “I killed it”. It all started few hours ago, when I put up my laptop to substitute the dead Dell…

Knowing my Fujitsu laptop’s battery was so old that it couldn’t hold more than 5 minutes of usable juice I pried its enclosure and revealed the 18650 cells and charging circuitry. As far as I knew the Li-Ion cells were healthy (they were in the good voltage range, not sure about capacity), so the problem was in the evil charge controller. Reading on the Net you can see that the smart chip in batteries remembers the age of the battery and throttles charging based on that age. I think this was my case.

Now the funny part: even if I knew that the smart chip’s memory depended on the connected cells, I disconnected one third of the 3S2P battery and reconnected it. No more responses from the battery. No more voltages on the pins. The laptop was going nuts trying to charge the battery. Now, THIS IS A DEAD BATTERY!

I do not regret what I did, it has been fun zapping the battery with a paperclip while trying to read voltages with the multimeter.


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