Just an update on the new Interstate SRM-29 I installed last weekend:

It came charged, of course, from Lee Auto Supply in Alameda.  I don't
know HOW charged, or how long the distributor had it on the shelf.

I installed it and camped with it for a couple of days before
installing the amp/voltmeter.

I didn't pay for an electrical hook-up at the campsite, and there's
no electricity to my hangar at Oakland, where I was doing the
work.  So I didn't have a chance to charge the battery fully until last night.

I plugged in the camper in a friend's driveway last night about 1
am.  The Pro-Sport charger immediately brought the battery up to
about 13 volts and 4 amps.

I just checked it again after about six hours of charging.  The gauge
now shows the Pro-Sport is putting out close to 14 volts at around 5
amps.  That tells me the battery is getting closer to a full charge.

(The little SLA-1161 didn't take this long to charge, of course.  By
the time it had charged for six hours, the Pro-Sport would long since
have switched on its green light, indicating the battery was fully
charged and the charger was in maintenance mode.)

Once the Pro-Sport flashes green, I'll be interested to see the
maintenance voltage and current, and, after unplugging the van, the
rest voltage of the new battery.

Yes, I'm a bit of a data wonk.  I'm thinking of putting together a
data logger in parallel with the Westach gauge to store the voltage
and current readings over time.

http://www.ladyada.net/make/logshield/lighttemp.html