you can get cheap chargers designed for Lead Acid's at your local hobby
store as must modellers use one
"TimPerry" wrote in message
news

"Mike Muderick" wrote in message
news:VYgQd.21992$ya6.3244@trndny01...
I have some 12 volt batteries that were used in alarm systems. They
apparently still have some good life in them. My question is about
charging
them. I was told that I can just take a 12 volt DC wall wart and connect
it
across the battery= pos to pos or pos to neg??= Is that true?

Maybe... the supply voltage needs to be far enough above battery voltage
to
allow it to fully charge.

The supply must be able to provide sufficint current to charge in a
reasonable amount of time (say 10 to 12 houres).

The supply must be current limited so as not to destroy itself or catch on
fire when shorted out (as in charging a depleted battery.

Do I need to
be concerned about current ratings vs. ampere hours of battery?

You need to be concerned about max charging current. too much causes
excessive heating which might lead to more serious issues.


Is there a way of checking the ampere hours of the battery if not stamped
thereon?

part number which leads to MFR spec sheets.

or (less accurately) compare volume and weight of you batteries with ones
of
a known value.

For some picture comparisons try http://www.emesystems.com/batcharg.htm

Thanks-
email appreciated at