I've got a 1989 Ram Van B250 5.2L High Top conversion. It's had battery draining problem since I bought it about 2 years ago. I tried to counter act it with a solar trickle charger thatI thought wasworking up until now.

I hooked up a multi-meter to measure the current... Only 10 Milliamps, which sounds normal, right? I don't think it's a normal parasitic drain that's happening slowly. It's almost like a wire from the battery is grounding out and causing it to completely drain randomly. I'll charge the battery to full, let it sit a few weeks and it'll be down to about 8 volts from the battery. The van doesn't move so you'd think the wires wouldn't be moving either. Is there something I'm not testing that I should be?

Thanks,
Mike

 

How old is the battery?
I've seen worn brake light switches turn brake lights on and off randomly. Also, if you have any windshield leaks, the water can drip down into electrical systems and cause temporary shorts. The same holds true for door jambinterior light switches.

 

Though I have not seen one personally I have heard of the switch in the lighted sunvisors with mirros going bad. Might pull the bulbs from them if your's has those.

 

If your battery has slowly been drawn down to 8 volts, she's a goner. It's sulfated, possibly internally shorted.

If it was quickly brought down to 8 volts and immediately recharged, then it might still work, but with less capacity.

Your alternator will work overtime trying to push some volts into this battery, which will not want to accept them.

Your battery is done, but you done want to fry a new one.

Since you know how to measure current with a DMM, hook it back up, and start pulling fuses till it goes to zero. That will narrow down what circuit is pulling juice.

I once forgot to reattach my ASD relay to the firewall. It rained and filled with H20 causing my fuel pump to run with the ignition off. It draws about 4 amps.

Consider pulling the ground from the battery when not in use or installing a battery cut off switch.

 

Would a 10 mA draw be draining my battery this quickly? I thought that was pretty normal for keeping the PCM and and clock charged.

 

No that little should not drain the battery in only a few weeks. When was the last time you did a hydrometer check on the battery? Your battery may have a weak cell that is drawing the battery down. I would do a hydrometer and/or load check on this battery to be sure that it itself is not failing you.

 

168 hrs./week x .010=1.68 amps/week. Hardly enough of a draw to drain the battery.

 

About 20 years ago a good old German mechanic taught me a trick concerning battery drain while we were working on a Datsun 280ZX. This particular car was killing new batteries with excessive drain while the car sat garaged for periods of two weeks. The car didn't get used much because the owner was an overseas traveller.The 280ZXhad a surprising amount of electronics in it, and it was nearly impossible to find the exact cause of the excessive drain. Many mechanics had tried to fix it before we accepted the challenge,but nonewere successful. After tracing circuits for two days we narrowed the drain to a part of the main wiring harness and isolated it. Then, we installed a simple Bosch 4-terminal relay and wired it to provide power to that circuit inthe harness only when the key was in the "on" position. Problem solved, and we made the owner of the Datsun very, very happy.