-=> MARK LEWIS wrote to TOM WALKER <=-

 ->> i've several 12volt, 11Ah batteries here that i'm wanting
 ->> to charge and load test... can i charge them with a standard
 ->> car battery charger? what settings should i use?

 TW> NO they are too small for charging on an Automobile Unit. Use
 TW> a motorcycle battery charger.

 ML> even the 2amp charge is too much? i have a charger that has three amp
 ML> settings for charging with... 2, 10 and 50 IIRC... the 50 is only for
 ML> starting boost and only good for about 30 seconds...

Slap a low voltage 1 amp bulb in series on the 2 amp setting.

 ->> what's the best way to load test them to see if they are still
 ->> good?

 TW> Fully charge them and then put a 1 or 2 amp load and measure
 TW> how long before the terminal voltage drops below 10 volts.
 TW> As an example 1 amp for 10 hours would be 10 Ah. That would
 TW> indicete a very good battery. Iusualy think of replacing
 TW> non-critical batteries when the Ah is about 1/2 of the
 TW> Battery rating.

 ML> hummm... how'm i gonna determine a 1 or 2 amp load to put on them?
 ML> someone else was telling me that maybe finding a 12volt light bulb of
 ML> some wattage would work...

 12 volt 1 amp ='s 12 watts

 ->> what does the 11Ah (Amp hours) really signify?

 TW> As stated about a rating of time vs Discharge current. With
 TW> smaller batteries ususaly discharging at 1/10 the Ah rating.
 TW> Whicy by the way is a good measure of a safe charging
 TW> current. Thus your 11 Ah battereis should be charges at
 TW> approx 1.1 Amps.

 ML> so the 2amp charge circut on my charger would be ok, then?

 ML> we've also got a wallwart charger for some batteries... output is
 ML> 15vdc{at}100ma IIRC... i'll have to take another look at the battery to
 ML> see if i can determine its characteristics...

 ML> if the units i have here are all good and i can get them all up and
 ML> wired, it would appear that in just "spare" batteries, i have 12vdc
 ML> 85Ah or so capability... that should give me some decent uptime... i
 ML> think that tomorrow i'll make me some buss bars and solder some
 ML> connector wires for hooking to the batteries i currently have...

 ML> )\/(ark

 
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