850 battery replacement

[macos_2017]

Has anyone managed to restore an 850 battery? I have two dead ones...
Also is the 820 battery compatible with the 850?

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[Thinkpad4by3]

Just don't screw up, or you' ll have a 1/850 chance of finding another one most batteries are very similar so taking it apart shouldn't be a pita.

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[fultontech]

There are a couple of issues in addition to dead cells that have made refurbishing the battery impractical.
The largest obstacle seems to be the physical circuitry that stops the unit from being recharged (over charged) once the voltage drops below a set point. I have read that people have bypassed this safety measure from the manufacture, though I don't recall where.
The intelligent programming stored in the battery was lost when the charge finally dissipated. There is no way to recover the original programming for the 800 series batteries. Someone could guess at what was there and write something, then figure out how to get the program onto the battery controller board.

[macos_2017]

I just source a new boxed 820 battery...anything is should do before using it?


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[fultontech]

I purchased old stock sealed boxes before. It's most likely dead. The safety circuitry I wrote about before won't allow the battery to be charged.