In article ,
"Tom" wrote:

I put all three on the shelf in the garage here in Ontario and tapped the
batteries together in parellel and put the charger back on the center
battery and haven't seen the green light come on that charger now for over a
week.

It's not a good idea to put lead acid batteries in parallel unless hefty
build-out diodes are used in series with each one of them before they
are connected in parallel. If the batteries are expected to be
discharged during use, the diodes should be arranged to let current flow
out of each battery but not into it. If the batteries are expected to be
charged during use, the diodes should be arranged to let current flow
into each battery but not out of it. The batteries have *EXTREMELY* low
internal resistance and there is no chance whatsoever that their
internal effective voltages will be absolutely identical. Absent the
diodes, whichever battery wants to have a higher terminal voltage will
discharge like mad into the others, until all their terminal voltages
are the same. Then you will have a badly discharged battery and one or
more charged ones, all in parallele. Until then, make sure the wires you
use are large, since the current flowing is going to be high. Not a good
situation.

Charging batteries in series instead of in parallel has its own
problems, but they're not as serious as the problem I have just
mentioned. The worst problem with charging N batteries in series is that
you need N times as much voltage from the charger as you would have
needed charging them one at a time.

David

--
David Ryeburn

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