The serial charger that I have been using can charge up to 20 amps AT SYSTEM voltage.
Currently, that means 20 amps at 72volts - so EACH battery could get up to 20 amps at 12V+.
1 or two amps would be WAY too slow.
My batteries hold roughly 100 amp-hours each. If the batteries are run half-down, you need to "re-fill" 50 amp-hours, or 50 hours at one amp - Two days plus....
An exception to that would be something like an electric riding lawn mower. If it takes 3 days to charge, so what? I don't mow the lawn any more often than once a week.
My friend Tom has an AC Dodge Neon. He has about 27 batteries or so, EACH one has its own little charger right on top. I think those chargers are 10 amps each. They are fully automatic, and switchable between 120 and 240V.
