On 8/15/2010 11:13 PM, firstname.lastname@example.org wrote:
About what? Surely you are not advocating charging 3 unequally
discharged backup batteries? That *is* the point. There is nothing wrong
with charging in series provided the batteries are similar and in a
similar state. Not that they would blow up, but the charging would be
unequal with the weakest battery taking less and less charge after every
cycle until it was dead. Hence the advice to discharge completely your
NiCads from time to time, so they all start at the same (fully
discharged) level. This is all basic ohms law with the voltage divided
between all the batteries, the weak link progressively falls in voltage
and hence the amount of charge it is given.
For unevenly charged batteries or batteries of different types, the
best option is to charge them independently.
FYI, large battery arrays are usually in a series/parallel combo of some
type. Look it up yourself.
Batteries are ALWAYS charged in series
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