darrenbrown

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Laptop battery cell replacement

After my laptop battery died, I replaced the cells individually. Cheaper than a whole new pack!

Here is the battery management PCB
Here is the battery management PCB
You can see each of the thermistors
You can see each of the thermistors
And also the wiring for the individual cell voltage monitoring
And also the wiring for the individual cell voltage monitoring

A local recycling drop-off location also accepted batteries. I was dropping some old alkalines when I saw a green light start glowing in the drop-off bin. I dug down into the pile of old batteries and pulled out about twenty MacBook battery packs that still showed full charge (according to the little green lights).

I took them home and opened one up to see that the lithium ion cells were 18650 style. The battery on my laptop hadn’t worked in months so I decided to replace the dead cells in my current laptop pack with the ones from the salvaged MacBook packs. With some careful soldering, I was able to swap the cells.

The loss of power reset the microcontroller on the battery pack so it assumed that the cells were brand new. After a few discharge/recharge cycles, it leveled out at about 80% of the pack’s rated charge. Not bad!