batery charging Answered
Having had to buy a dedicated charger for some 18650 cells (at my wife's insistence) I took an interest in these cells for the first time and their smaller cousins the 123a. At with maximum capacities I've come across so far of 3700mAh and 2000mAh respectivley that's twice the capacity of the battery in my smart phone and 2.5 times the capacity of the one in my basic bar phone.
The smart phone width would accommodate 3 of the 18650 cells (6 days without charging at my rate of use) and the bar phone possibly 4 of the 123a's (70 hours talk time or 10 months on standby).
Yes this would mean a custom made back, but there is at least one instructable on molding a GRP/ carbon phone back adjusting it to take extra cells and maybe ports just needs modeling clay. I suppose I could just carry a power bank, but why if the phone can be its own power bank? Removing the guts of a power bank and building a new phone back to accommodate them may be the simplest answer to this but, my questions are:-
A) I've got old mobiles laying around could I use their charging circuits to charge these standard Li-ion cells?
Assuming that is a yes that would mean a long charge every 6 days/ 10 months.
I gather there are problems associated with parallel charging/ discharging of Li-ion cells and over discharging so,
B) Any advice on doing this other than don't?
On the assumption that's a don't or even if its not this strikes me as a safer possibility.
C) Could a micro controller be configured to discharge one cell to its limit then switch to the next full cell.
D) Could a micro controller be configured to charge one cell to capacity then look for the next under capacity cell and charge that.
E) if so could it do both at the same time?
If A is possible and the rest not then a multi position switch is probably the answer.