Thread: A novel idea to fix the USB port
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Estel is offline Estel
2012-09-01 , 03:06
Posts: 5,028 | Thanked: 8,613 times | Joined on Mar 2011
#25
Originally Posted by Fallingwater View Post
Not entirely correct.
First up, the CC/CV (constant current / constant voltage) charging process switches to CV somewhere at 80% capacity, not 50% --edit-- I got doubtful about this and I'm currently looking for relevant information --end edit--
Secondly, the N900 definitely does charge its LiIon cell to 4.2V; the negligible power it's using to keep itself running in the meantime is irrelevant.
Of course, it was also a "mental shortcut" from my side - when it switched to CV, depends on current during CC phase. Higher current in CC (as % of battery C) - the sooner CV will happen. So, charging standard bl-5jwith 1250 mA it happens near 50% SoC, but charged with 950 or 800 mA, CV will jump in around 80% of SoC.

As for N900 LiIon being charged to 4.2, I can't confirm it. Every measurement I took - both from in-device (bq27200) and using external components - shows little less than 4.2V as absolutely max. IIRC, it was something like 4150mV-4170mV at most.

Genuine N900 charger was charging at full 950 mA during CC, after all (just tested with one borrowed from a friend) - so it's limited by chip. Haven't tried to charge with 1250 mA - it isn't my charger, and I don't want to fry it during experiment

/Estel
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