> Hi all
> I have a small project I am working on and it is a, intelligent Pb acid
> battery charger for a system with 3 pcs of 12 volt Pb acid batteries
> connected in series each battery is a 100Ah type. I want to charge them with
> 10 A, and the charging have to stop when they are fully charged either
> controlled by the cell voltage, time or some thing else I haven't thought
> about. I want to use PWM and of cause this charger have to be controlled by
> a processor.
> I don't want to invent every thing again and there have been a lot of
> threads regarding charging batteries, so perhaps there have been one
> regarding a project like mine. If some one have a link to a similar project,
> or some other information I can use in my project I will be very pleased.
>

The best way to charge this battery of batteries is to charge each
unit as an entity in itself. Simply charging in series (10A @ ~42
volts) will cause the charging to proceed at the worst batteries
rate leaving the best batteries not fully charged. Also it is
efficient to charge Pb batteries at constant current initially(.25C
or 1/4Amps vs A/h Capacity is normally max rate) then  moving to
constant V when 13.8volts is reached on the charging curve.

One way to do this is to supply an isolated ac power bus and connect
each charging circuit inductively to this power source... i.e. to
float each charger. The charger then takes care of just its own
battery in the chain, reporting to a central processor (via isolated
comms) what its particular status is.
This is what cutting edge electric vehicle chargers do... as in
20+ battery banks.

I'll wait for "you dont know s**t from clay" comments now.
Lance Allen
Uni of Auckland
New Zealand