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bluedog225
03-02-2016, 03:30 PM
I came across a 12 volt jump pack in my dad's garage. Surprisingly, it is still reading 11-12 volts. My multimeter is not very precise.

The transformer and charging cord with the little plug to charge it is missing. But I have a randon one that fits and puts out 12.6 volts at 1.5 amps.

Is that enough voltage to charge?

I'm not very interested in sourcing a new charger for this but will try to keep it alive and have a few uses for it. Mostly lighting.

Alternatively, could I charge it through the jumper cables with a regular battery charger?

http://www.amazon.com/Brand-Jump-Starter-Power-Supply/dp/B00LK3YFSO/ref=pd_sim_sbs_23_2/187-3983534-9263666?ie=UTF8&dpID=41htC-W1PlL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=1NRKEBKRPK7GGZTSFGE5



thanks

Tom

skaraborgcraft
03-02-2016, 03:35 PM
I always thought 13.8 was a minimum. A healthy charged 12v battery should read 12.8v at rest.

bluedog225
03-02-2016, 03:45 PM
Yeah, that's what I keep reading. I opened it up and it looks like it will be easier to just hook up the battery to my dumb battery charger. Thanks.

Norman Bernstein
03-02-2016, 03:46 PM
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The transformer and charging cord with the little plug to charge it is missing. But I have a randon one that fits and puts out 12.6 volts at 1.5 amps.

Is that enough voltage to charge?

Nope. By the way, the advertising blurb on Amazon merely says 'sealed lead acid battery', which is not necessarily AGM.

A conventional charger will probably work OK.

bluedog225
03-02-2016, 03:57 PM
You are correct. Sealed. Just assumed agm. Thanks.

bluedog225
03-02-2016, 04:26 PM
I've got a dumb charger. It has a twist timer and a 2 amp and 10 amp setting.

Is 10 amps for 5 hours too much for this little 17ah battery? Looking for a good charging regimen. Drowning in internet info overload.

Norman Bernstein
03-02-2016, 04:48 PM
I've got a dumb charger. It has a twist timer and a 2 amp and 10 amp setting.

Is 10 amps for 5 hours too much for this little 17ah battery? Looking for a good charging regimen. Drowning in internet info overload.

The settings don't mean all that much; the amount of current that a typical charger can produce is limited by design, in the 'crude' sense... how much iron in the transformer, etc. The lower 2 amp setting probably engages some sort of current limiter.

The general rule of thumb, for lead acid batteries, is that anything over a few percent of nominal battery capacity can cook a battery, if left on indefinitely. Also, the common rule of thumb for charging lead acid batteries is 'C/5', maximum, i.e., 20% of the amp hour rating of the battery. By that rule, you should be safe, on the 2 amp setting... but not indefinitely.

This does NOT mean that some people won't ignore the rules and attempt to cram as much energy into a battery as possible... but it's certainly not good for the battery, and potentially dangerous or damaging, especially in a sealed lead acid battery. If the seals pop, say goodbye to the battery.

If I were you, I'd try a few hours on the 2 amp setting, and then, if you can, test the battery voltage while the charger is still on.... if you're reading more than 13.8 volts, turn it off.

bluedog225
03-02-2016, 06:22 PM
Great. Thanks!

You put me on the right track I always have to relearn this stuff.

This was helpful:

http://www.arttec.net/Solar_Mower/4_Electrical/Battery%20Charging.pdf