Quote:
Originally Posted by Yourcat
I assume you open the old Kindle lipos to extract the charge/control chip. I would not try to load nimh here.
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Actually, I replace the LiPo in the dead kindle battery, leaving the connectors, circuit board, and mounting frame all intact. If the replacement LiPo does not have its own thermal protection (mine does), you need to wrap the battery pack up again so the LiPo heat can propagate to the kindle circuit board in the battery pack, to manage charging temperature.
NiMh has a different charging curve. Perpaps safe with 3 NiMh cells (never reaching peak voltage), though LiPo is much preferred. Folks HAVE used NiMh in a kindle, in fact (but using "kernel hacking" custom firmware instead of kindle battery circuit board). Overcharging NiMh makes them start thermally DISCHARGE, so they use a peak charging algorithm. LiPos use a dual charge algorithm (fixed current until they reach maximum voltage (4.2v) then a ramp down current until they are at full capacity (same 4.2v, but much longer discharge time).
Always keep in mind that LiPos are a potential fire hazard, but usually only after they have been physically damaged, or charged or discharged beyond their specifications.
And if you use a battery from an old phone or camera (instead of an R/C toy), probably no need to disasemble it -- just wire the '+' and '-' to the corresponding pads on the kindle battery PCB. I plan to test an old phone battery in my kindle soon.