On 08/01/2011 12:08, Michael Watterson wrote:
>> For financial safety of supplier if nought else.
>> >
>> >  I'd argue (but I may be wrong) that there is no great need to
>> >  artificially limit cycle life of a LiIon pack. By all means control
>> >  voltages, gross discharge, charge rates, charge when V low, MAYBE no
>> >  charge when very very low (although I'd expect it to usually to be
>> >  safe to TRY to bring up a cell from almost any voltage).
> Perhaps designers overcautious. But doesn't prevent faulty made cells
> going on fire/exploding in normal use.

I suspect it's more to do with financial reasons too, so they can force=20
you to pay up to half the price of the laptop to purchase a new one.
  I haven't heard of too many Li-Ion batteries exploding because they=20
got "too old". Wouldn't be too hard (I think) to detect this point and=20
stop charging when the battery "decides" it's dead (i.e. get the most=20
possible cycles out of it), rather than enforcing a set limit.
I investigated battery protocols etc too a whle back, and agree it's a=20
lot more complicated than many other batteries as MW says. IIRC, most=20
use a one wire protocol (name escapes me - MC have an app note on using=20
a PIC to interface with a Li-Ion battery) and a coded eeprom to detect=20
correct charger etc. I managed to rig up a solar charger for my Sony=20
laptop battery with not too much hassle though.
If/when replacing the cells, I would definitely suggest keeping power=20
supplied at all times until new cells are in place, as mentioned (I saw=20
an instructable about replacing cells that goes through this quite well,=20
have a search on there)
As mentioned also, be careful... ;-)




--=20
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