I have a couple of 12V 7.5AH lead acid gel cell rechargeable batteries
that were installed in series in a 24V fire alarm panel. After just
slightly over a year the panel suddenly started beeping a low battery
signal. I pulled both batteries out replaced them and the problem was
resolved. I took both old batteries back to the shop and charged them
individually at 100ma. for a few days. They both came up to over 14V.
After sitting overnight without charging hey both remained just under
13V. So now I would like to load test them to see which one is falling
down on the job. Does anyone know what the proper load would be to do
this and also the minimum terminal voltage I should expect to read on a
fully charged battery while the battery is loaded in such a way? Is
there a specification for how long the load should be connected before
you read the voltage and ultimately assess the quality of the battery?
Thanks very much, Lenny Stein, Barlen Electronics.

wrote in message
oups.com...
I have a couple of 12V 7.5AH lead acid gel cell rechargeable batteries
that were installed in series in a 24V fire alarm panel. After just
slightly over a year the panel suddenly started beeping a low battery
signal. I pulled both batteries out replaced them and the problem was
resolved. I took both old batteries back to the shop and charged them
individually at 100ma. for a few days. They both came up to over 14V.
After sitting overnight without charging hey both remained just under
13V. So now I would like to load test them to see which one is falling
down on the job. Does anyone know what the proper load would be to do
this and also the minimum terminal voltage I should expect to read on a
fully charged battery while the battery is loaded in such a way? Is
there a specification for how long the load should be connected before
you read the voltage and ultimately assess the quality of the battery?
Thanks very much, Lenny Stein, Barlen Electronics.

You can use an automotive lamp as a load.

A 1 amp load should drain the battery in 7.5 hours. 10 amps should drain it
in 45 minutes. A fast drain load will not give as much AH capacity, by the
way.

In article .com,
wrote:
Does anyone know what the proper load would be to do
this and also the minimum terminal voltage I should expect to read on a
fully charged battery while the battery is loaded in such a way? Is
there a specification for how long the load should be connected before
you read the voltage and ultimately assess the quality of the battery?
Thanks very much, Lenny Stein, Barlen Electronics.

Normal way to check is to discharge is at the 20 hour rate - ie 1/20th of
the nominal capacity. So with a 20 amp/hr battery you'd load it at 1 amp.
Terminal voltage should be 10.8, IIRC.

--
*I wonder how much deeper the ocean would be without sponges.

Dave Plowman London SW
To e-mail, change noise into sound.

On 2005-10-31 13:33:46 -0800, "
said:

I have a couple of 12V 7.5AH lead acid gel cell rechargeable batteries
that were installed in series in a 24V fire alarm panel. After just
slightly over a year the panel suddenly started beeping a low battery
signal. I pulled both batteries out replaced them and the problem was
resolved. I took both old batteries back to the shop and charged them
individually at 100ma. for a few days. They both came up to over 14V.
After sitting overnight without charging hey both remained just under
13V. So now I would like to load test them to see which one is falling
down on the job. Does anyone know what the proper load would be to do
this and also the minimum terminal voltage I should expect to read on a
fully charged battery while the battery is loaded in such a way? Is
there a specification for how long the load should be connected before
you read the voltage and ultimately assess the quality of the battery?
Thanks very much, Lenny Stein, Barlen Electronics.

If you have a Dick Smith ESR meter (kit) you can run an internal
resistance test and compare that with a good one. If it is to far off
the battery is probably toast. Oh, don't have the back-to-back diodes
installed on the ESR meter for this test!

http://www.flippers.com/esrkthnt.html#battery

John :-#)#
--
(Please post followups or tech enquires to the newsgroup) John's
Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 Call
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games)
www.flippers.com "Old pinballers never die, they
just flip out."