Bought a new battery, as I thought the old one was no longer holding charge well, and the new battery keeps going dead as well. Seems to take about 4 or 5 days for it to go dead. Can't figure out where the drain could be from. Any ideas what could cause this? A friend said he once had some dirt in his trailer wiring harness connection which was conducting just enough to slowly drain his battery. Took him several months to figure out the problem. So other than corroded / dirty connections, what else can I look for?

 

what aftermarket mods do you have?

stereo / fog lights / alarm system / etc?

 

clean all connections and check your alternator...

 

I had a Jacob's ignition that I did not realize was running all of the time--key on or off. Killed an Optima red top in no time.
Pulled off the Jacobs and threw it in the trash (it was my seventh system and I had tired of the warranty process) and upgraded to a yellow top for $40 or so.
But I also currently have a small current leak down that I need to trace. I just keep a trickle charger on for now.

 

Remote starter, but I removed it to try to troubleshoot the problem.. Nothing else

 

I had the same problem and got tired of looking for it, so I installed a battery cutoff switch. Works great. I have also seen them at Wal-Mart if you don't want to pay shipping.

Rob

 

How do they install?

 

The cutoff switch ties in on the power line from the battery. I've been needing to install one in my truck for storage. I've had multiple drain issues on my '86 that were in the end self induced. The best way to rule out systems in your truck is to pull the postive lead of the battery and put a voltmeter from the positive terminal to the positive lead. Set the voltmeter to DC volts, and in a perfect world it should read "0." There's always going to be some minor drain (clocks, radio memories, etc...). Should be small volts, if not millivolts. If you've got hi volts then, go to the cab and start pulling fuses. There's also fuses in the engine bay. Do one at a time, if you go through all of them and no changes, then go through stuff you added. Good luck!

 

Sorry, but if you are measuring positive terminal to positive lead, should it not be an ammeter that is used for measuring current flow? I've been meaning to do that for a few days.... I keep puting it off since I gotten attached to my christmas present (MS Flight Simulator X); its a great way to waste hours of my day when I should be doing other things. Good idea about pulling fuses one at a time. I was wondering exactly how to go about looking for the leakage in a systematic fashion; your way sounds very logical and should at least narrow down my search to one system (I hope.)

 

I have always used an dmm to check for excessive draw. Set it up for amps. Set it for the highest amps possible. Loosen the negative battery terminal and attach one lead to the terminal with an alligator clip and poke the other lead to the negative battery post. Lift the terminal off of the battery with the other lead still poked on the post and note the reading. Im not sure what the spec is but it should be below 50mA. Make sure the key is off and out of the ignition with no accesories on. Good luck!

 

You have a Parasitic Load. Normal parasitic loads are below 75 milliamps. When the parasitic load is greater than 75 milliamps, batteries will drain more quickly. Glove box, trunk, and under hood lights that do not automatically turn off when the door is closed or shorted diodes in alternators are the most common offenders. With the ingintion off, series a Ammeter with the negative of your battery the reading will show your parasitic load.

 

OK, I just did some testing and the numbers seem REALLy high. I tested using two different ammeters and got different numbers. using one ammeter on the 10A circuit, I got an initial spike of about 10 and then it quickly dropped off to 0.42. I then tried another ammeter and got no real readings on the 150mA scale, so I switched to 50mA and it was off the scale. Another thing I noted was that the longer i waited between tests, the larger the initial spike in current. For example, when I used the first ammeter, it initially gave a current spike of about 10A (then dropped off quickly). But when I tried a second time, the initial spike was less than 2A. I waited a little longer before another probe, and that time it was about 6.5A. Do these readings seem abnormally high for a drain that seems to kill the battery charge in about 3-5 days?

 

This project was on the back burner for a while. I did some testing last night pulling fuses one at a time. The parasitic load is on the "DOME" circuit; the very first one I tested. I guess I'll have to investigate to see what is on this circuit and take a few guesses as to what the problem is. I can't find any lights that are on in the interior.

 

The initial spike is just a capacitive discharge. The settled draw is what you want to know. The reading you got off-scale on 50ma should be visible on the 150ma scale. One of those is wrong, you should find out which before you decide what your passive draw is. (btw, you should start at the highest range, let it settle before stepping down the range, to avoid potential damage to the meter)

Basically all you should be drawing is your clocks, which should be very low... milliwatts. For example, 50ma would be (P=EI) or 12v X 50x10-3 = 600mw = 0.6watts. Even that is a lot just to power clocks, but not enough to discharge your battery in terms of days.

An incandescent bulb such as a glovebox lamp might draw 7watts or 7000mw, which might be a problem in terms of days, depending on the battery and its condition.

Headlights and tailights left on might draw around 120 watts total or 120,000mw, which will kill most batteries in a few hours, in terms of leaving enough charge to start the vehicle.