"Mark" wrote in news:1156831412.903466.125420
@b28g2000cwb.googlegroups.com:

Have you actually done that? 1.5 amp charger charging a 500AH bank or
larger.

I'm guessing a 500AH bank would need at least a 5 amp charger to bring
it up to 14.2 volts and a fully charged state. A 1.5 amp charger might
bring it up to something like 80% charged before it can't up the
voltage above 13.2 volts or so, and just floats the partially charged
bank. Could be wrong though, anybody wanna chime in here with
firsthand experience?

I do agree a 1.5 amp charger will float a fully charged 500AH bank,
that's 36 amps a day, more than the natural discharge loss of the bank.
But will it charge it up from a deeply discharged state?


No, actually it was only 330AH of golf cart 16H batteries.

All this is quite moot on a "working boat" sitting in a slip. The 1.5A
charger is NEVER going to recharge or even keep charged a boat that has
LOADS running all the time, like bilge pumps cycling on and off to keep
the dripping packing glands from flooding it. I don't recommend it for
that.

What I DO recommend the little brick for is any boat that's shut off
sitting on a trailer or in a dry stack or put up for the winter. The
battery is disconnected from all loads and only needs a VERY slow
recharge, like my little brick creates, over long storage periods, longer
than a week.

It's not for charging the boat battery at the slip between uses. What IS
really nice about it is you can go off for 3 months and come back to
batteries that are REALLY hotly charged, so slowly, and NOT have to add
water to them, at all! Charging this slow rarely makes a bubble of
hydrogen. I've never seen electrolyte drop at all from the 75AH deep
cycle driving my dink's electric outboard to the 330AH beasts in my shop.

At $30 a charger, if you have two banks of house batteries, use two
little bricks, not one, on separated battery banks, eliminating the
cross-discharging that always goes on in parallel. (You won't hurt them
if you screw up and put them in parallel...been there, done that. Then,
you'd have a 3A, stepped-charge charger as one of them will always have a
little different trip point than the other, shutting one down first.

This morning, the 1.5A brick charger is recharging some utility gelcells
for me....from 2.2AH to 12AH...I have laying around the shop. When it
starts charging a small 12V gelcell like these, the "charged" LED
immediately comes on after 5-10 seconds, and starts blinking on and off
as 1.5A is WAY too much charging current for a 2.2AH gelcell. The "on
time" (when the LED is off) and the "off time" (when the LED is on)
exchange time lengths as the little batteries charge up. Eventually, the
LED stays on for many minutes and occasionally winks off, immediately
coming back on because the little battery is fully charged. It's easy to
see when the charge cycle is completed, and forgetting it for a day seems
to make no difference at all.

--
There's amazing intelligence in the Universe.
You can tell because none of them ever called Earth.