TheSamba.com :: View topic - Help finding the cause of my battery drain

Tue Sep 23, 2008 11:43 am

Hello,

Recently my 86 Transporter has acquired an odd battery drain, and I have not been able to locate the source. I hooked my voltmeter up and measured the milliamp that are drawn from the battery and initially its in the 170 Milliamp range then it slowly drops off to 5-8 milliamp, but it takes a 45 seconds to drop. If I leave the van sitting for more then a few hours the drain is so strong that it will sufficiently discharge the battery and won't start.

I have removed all the fuses one at a time and none of them had any effect on the drain. I then removed all the terminals from both the starter and the Alternator. Neither of those had any effect on the drain. Then I unplugged the key switch and that had no effect on the drain either.

There are 3 wires coming into my positive battery terminal. The large main wire. Then two smaller wires, both have red sheaths but one has a white stripe. The drain is coming from the smaller wire that has a solid red sheath.

What have I not checked? Has anyone else experienced this same issue? Is there any circuitry between the battery and the starter? I've checked the Bible, but reading wire diagrams is not my strong suit.

Thanks,

Tue Sep 23, 2008 11:46 am

Does it have an alarm? When my alarm started to go bad, it was draining my battery pretty badly. Power locks going bad will also drain the battery.

Tue Sep 23, 2008 12:14 pm

No unfortunately, there is no alarm and no power anything on the van.

I'm suspecting a short, but in my experience that doesn't explain why the drain starts off high, then gradually tappers off.

Thanks for the thought though.

Tue Sep 23, 2008 1:02 pm

I'd have the battery charged and properly load tested. I would think a good battery could handle a 1 amp draw for 24 hours. You are talking about milliamps. I have seen stereos exhibit that behavior you describe. Rather than use a volt meter which is good, try this. Take a cheap 12volt test light and put it between your ground cable and battery. If it lights, you have a decent draw to kill the battery over time. If a 12volt light won't light you need to check elsewhere. An arch when connecting the ground cable is also a good indicator of a draw or short.

Tue Sep 23, 2008 2:20 pm

Remove the ground to battery wire. Put an amp meter between the ground strap and the battery. This will show the draw on the battery. Pull fuses and replace them one at a time and note the drop in amp draw. when you find the circuit that draws the offending amount of power, then trace down that one and you will find you great sucking sound of electricity.

Tue Sep 23, 2008 4:17 pm

An acceptable amount of draw not to kill a good battery is 30 milliamps. If it's less than that you probably have 1 bad cell in your battery. When you are checking for a drain make sure that you start the truck and turn EVERYTHING on and off before shutting it down and checking. I have seen drains where disconnecting the battery to get a meter in between would then stop the drain . If you are absolutely convinced there is a drain, you have have to check with a very sensitive clamp-on ammeter. You seem to know what to look for, but is that solid red wire oem ? or has somebody added something in the past. I don't have my bentley here so i can't tell.

Tue Sep 23, 2008 11:06 pm

Is it set up for a 2nd battery under the driver's seat? Normally Vanagons have NO extra wire hooked to the positive cable. I think the red/white stripe wire goes to the auxiliary battery used for a refrig or camping loads.
BTW what year?
Al

Wed Sep 24, 2008 3:44 pm

I just had the battery checked and it's fine. No issue there. My van is an 86, and there is not a 2nd battery under the driver seat. Its a transporter, so no fridge to run.

I also thought it was odd to have 3 wires on the positive terimal, but because they all run into a protected cluster that heads to the engine I assumed they are OEM Although just looking at the contects it looks like it may be an add on job that was done at some point. I'm going to spend some time tomorrow and see if I can trace those wires and find where they go.

I'll try the test light, but there is an arch when reconecting the ground, so there is a draw somewere of that I'm pretty sure.

After the battery is disconected and all systems on the van are let to reset the drian is still present. I already pulled all the fuses and that had no effect on the drain. What circits are not fused? Head light relays?

I'll try the radio, and I also thought about the clock as a possible suspect.

Thanks, and any other ideas are much appreciated.
Matt

Wed Sep 24, 2008 4:56 pm

I have also heard of the internally shorted alternator causing a quick drain. Try taking it out of the loop also. The lady who sold my van to me quit driving it due to the fast run down of battery and tow bills. All I have ever done was to replace ignition switch as I have had to do in all my VWs since 1985. I also found the loose chassis ground and tightened it. Charging and not failing every since. David