I had left the lights on in my '74 Powerwagon yesterday, and when I came out to go somewhere the battery only had eight volts in it. I got out my spare Optima battery, hooked it up to the truck with jumper cables, and started the engine. Now the ammeter always shows charging, moderate at idle, fully pegged whenever the engine's above 1200 RPM.

I checked with my voltmeter and at the alternator output terminal it's showing 14.2, about normal, and at the battery 13.2 when the ammeter is pegged. When I shut the car off it rapidly drops to 12.6, and then continues to settle in at 12.2 volts, which means there's a small current draw in there somewhere.

I hooked the spare up by going Positive-Positive-Negative-Negative, not PPN-Frame as I should have.

It did not do this before the battery was drained. My brother and I had just been off-roading, and every time the truck stalled out (No off-road kit in the carburetor), we started it back up and it charged the battery normally, and the ammeter showed normal operation.

Did I perhaps goose the voltage regulator when incorrectly hooking up the spare? Or perhaps my battery's hosed. Those are the only two things I can think of. I have not yet tested the regulator, simply because it's hot here, and I didn't want to climb up into my engine bay while swimming in sweat.

You had to jump the battery because it was pretty dead.

Looks like your charging system is working its darnedest to get it charged again. Sounds okay to me.

Don't jump to conclusions until things get back to "normal" (a fully charged battery). If you want to make the alternator work less, charge the battery with a plug-in charger. Judge things only when the battery is all the way back up. In the mean time, don't freak out.

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In the mean time, don't freak out.

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Until your car blows up

Like mentioned.. I would put a battery charger on it to top up the battery during the day if it was me

I realize it's trying to charge, but the part that gets me is the virtually immediate drop from 13.2 volts to 12.2 at the battery. Usually it takes a little while for the residual voltage to bleed off.

Recharge it fully before you pass judgement.

And quit freaking out.

Really.

If you recharge it all the way, and funny things are still happening, then call me an idiot.

(But please don't be like my wife, going directly to step two.)

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(But please don't be like my wife,Jeff,the neighbors, and everyone else going directly to step two.)

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I started it up after letting it sit overnight, and the ammeter is no longer pegged. Now it's just slightly on the charge side.

I'll just let it roll.

But step two is so fun.