On 20 Feb 2005 at 20:45, Christopher Zach wrote:
> Oddly enough, this would indicate that the transformer could probably
> safely charge AGM batteries as well, since the charge current tapers off
> as the
> batteries hit full.
I don't recommend that. The GE charger doesn't have precise enough
control to
charge VRR batteries. Its voltage regulation, though better than that of
a
plain (non-ferro) transformer charge, probably isn't good enough. There's
no
temperature compensation. And as presently configured, the finish voltage
and
current are too high.
The other problem comes from the way the pack is tapped to supply voltage
for
the lights and lift, which causes chronic pack imbalance. That's not much
of
a problem for flooded batteries, which can withstand the overcharge
necessary
to equalize on every cycle and still last for several years of use.
However,
it would destroy VRR batteries in short order.
I use gel batteries in my ET with reasonably good results, but I charge
each
12 volt module individually with "modular" chargers. The ones I use
aren't
really optimal either since they don't implement temperature compensation.
I'm beginning to see a loss of capacity now, perhaps because of
undercharging
in cold weather, but so far the pack is still usable.
One could just as well (maybe better) charge the pack in series, using a
36
volt charger and a more precise charge controller. To maintain pack
balance,
you'd need to either fit DC:DC converters for the lights and lift, or
change
the lights and lift over to 36 volt units.
David Roden - Akron, Ohio, USA
1991 Solectria Force 144vac
1991 Ford Escort Green/EV 128vdc
1970 GE Elec-trak E15 36vdc
1974 Avco New Idea 36vdc
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Their talk was the talk of sordid buccaneers: it was
reckless without hardihood, greedy without audacity,
and cruel without courage; there was not an atom of
foresight ... in the whole batch of them, and they did
not seem aware these things are wanted for the work of
the world.
-- Joseph Conrad, "Heart of Darkness"
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