Battery drain

satchmo · Post by **satchmo** » Sun Mar 28, 2010 7:56 am

The battery on my 87 Vanagon drains completely if I don't start it at least once a week. I made sure everything is turned off and I checked all the wires I can check without fishing them out of the wire wrap. I made sure the wiring on the items I messed with is all good. This is starting to tick me off.

I read on another site that a good way to go about finding a current leak is to put your DC Amp meter (yeah, right, who has one of those laying around??) on the main battery cable then remove fuses one at a time until you find the circuit responsible for the drain. Then you need to check all the wires on that circuit.

It seems to me that only a few circuits/wires would have constant voltage with the ignition off and there must be some places that are more likely culprits for current loss than others. Do you have any suggestions?

I will likely start tearing into the dash and relay area tomorrow. Let me know if you have any ideas. Thanks.

Tim

vwlover77 · Post by **vwlover77** » Sun Mar 28, 2010 8:28 am

Don't you have a standard VOM (volt-ohmmeter)? Most have an ammeter built in. If not, go buy a cheap one at Radio Shack. Very useful!

Do you have an aftermarket radio, CD player, booster amp, or CD changer installed? I had a defective changer in my New Beetle that drained the battery in a week.

satchmo · Post by **satchmo** » Sun Mar 28, 2010 9:08 am

vwlover77 wrote:Don't you have a standard VOM (volt-ohmmeter)? Most have an ammeter built in. If not, go buy a cheap one at Radio Shack. Very useful!

Do you have an aftermarket radio, CD player, booster amp, or CD changer installed? I had a defective changer in my New Beetle that drained the battery in a week.

I have both a digital and an analog VOM. Neither one measures amps that I can tell. Do you know of some way to hook it up to do that?

There is an aftermarket CD player that has a removable face, so I have taken that off and checked the wiring. No help.

Tim

Post by **Amskeptic** » Sun Mar 28, 2010 9:26 am

satchmo wrote:
vwlover77 wrote:Don't you have a standard VOM (volt-ohmmeter)? Most have an ammeter built in. If not, go buy a cheap one at Radio Shack. Very useful!

Do you have an aftermarket radio, CD player, booster amp, or CD changer installed? I had a defective changer in my New Beetle that drained the battery in a week.
I have both a digital and an analog VOM. Neither one measures amps that I can tell. Do you know of some way to hook it up to do that?

There is an aftermarket CD player that has a removable face, so I have taken that off and checked the wiring. No help.

Tim

You have the single battery under the passenger seat?
At night, you can see the spark when you lightly touch the negative terminal to the post. Nice and comfy inside the car with all consumers off, you can remove each fuse and check the terminal. If every single fuse has been tested and you still get the little spark throughout, try the voltage regulator plug or plug at the back of the alternator. When a diode blows, it creates a nice little ground path.
Colin

midatlanticys · Post by **midatlanticys** » Sun Mar 28, 2010 5:51 pm

dingo wrote:Heres a couple of electrical test i came across:
Checking Alternator diodes: Put the meter on 'AC' and connect black lead to a good ground, and red lead to the 'Bat' terminal on the alternator (NOT at the batt.). With engine running, a good alternator should read less than .5 VoltsAC. A higher reading indicates faulty or damaged diodes.

from here; viewtopic.php?t=295

Satch, maybe a stupid ?, but does the battery go flat if the neg. cable is disconnected? meaning the batt. is not holding a charge?

satchmo · Post by **satchmo** » Sun Mar 28, 2010 10:16 pm

midatlanticys wrote:
dingo wrote:Heres a couple of electrical test i came across:
Checking Alternator diodes: Put the meter on 'AC' and connect black lead to a good ground, and red lead to the 'Bat' terminal on the alternator (NOT at the batt.). With engine running, a good alternator should read less than .5 VoltsAC. A higher reading indicates faulty or damaged diodes.
from here; viewtopic.php?t=295

Satch, maybe a stupid ?, but does the battery go flat if the neg. cable is disconnected? meaning the batt. is not holding a charge?

Haven't tried that (neg cable disconnected, I mean) yet, but the battery is less than a year old. Thanks for the other link.

Tim

glasseye · Post by **glasseye** » Mon Mar 29, 2010 7:03 am

satchmo wrote:
Haven't tried that (neg cable disconnected, I mean) yet, but the battery is less than a year old. Thanks for the other link.

Tim

Don't rule out a bad battery. I preemptively replaced the Asstro's perfectly good battery only to have the new one display exactly the symptoms you're seeing a year later.

satchmo · Post by **satchmo** » Mon Mar 29, 2010 7:07 am

Amskeptic wrote: You have the single battery under the passenger seat?
At night, you can see the spark when you lightly touch the negative terminal to the post. Nice and comfy inside the car with all consumers off, you can remove each fuse and check the terminal. If every single fuse has been tested and you still get the little spark throughout, try the voltage regulator plug or plug at the back of the alternator. When a diode blows, it creates a nice little ground path.
Colin

I checked all the fuses for a spark at the battery neg. terminal. With #3 removed, the spark is diminished almost to zero, but there is still a little one. Should there be no spark at all? It seems like every battery I have ever re-connected has at least a very tiny spark.

So #3 fuse is the interior lights, the radio and the cig. lighter. I'll take a look at all of those today. I will also take a look at the VR.

Tim

chitwnvw · Post by **chitwnvw** » Mon Mar 29, 2010 7:09 am

glasseye wrote:Don't rule out a bad battery.

I 2nd. Assumptions when troubleshooting are bad.

airkooledchris · Post by **airkooledchris** » Mon Mar 29, 2010 10:08 am

it does seem like an easy thing to test for.

disconnect the battery, then see if it still seems drained after a week of non-use.

midatlanticys · Post by **midatlanticys** » Mon Mar 29, 2010 6:26 pm

satchmo wrote: With #3 removed, the spark is diminished almost to zero, but there is still a little one.

leave #3 out and start pulling the other fuses to see if you can eliminate the little spark too. You may find two circuits draining the battery. . . . or if the battery is on the way out you can watch it die on the VOM with the neg cable disconnected; 12.6v today, 12.2v tomorrow, 11.9v the next day etc and eventually DOA.

satchmo · Post by **satchmo** » Fri Apr 02, 2010 8:45 pm

Just an update: Battery is good. I left it disconnected all week and it is staying happily at 12.8 volts. So I am loosing juice someplace when it is connected. It looks like it is the radio, cig. lighter or interior lights. I will inspect all the connections on the circuit for fuse #3 when we get our spring weather back (32 and snowing/raining/blowing all day today, with a high wind warning tonight - bah!).

Tim

Post by **Amskeptic** » Sat Apr 03, 2010 2:36 pm

satchmo wrote:Just an update: Battery is good. I left it disconnected all week and it is staying happily at 12.8 volts. So I am loosing juice someplace when it is connected. It looks like it is the radio, cig. lighter or interior lights. I will inspect all the connections on the circuit for fuse #3 when we get our spring weather back (32 and snowing/raining/blowing all day today, with a high wind warning tonight - bah!).

Tim

Find the problem! This is more exciting than "24".
A tiny little spark is OK for time display or radio memory.
Colin

glasseye · Post by **glasseye** » Sat Apr 03, 2010 4:27 pm

Amskeptic wrote:This is more exciting than "24".
Colin

You guys need to get out more.

static · Post by **static** » Sat Apr 03, 2010 6:21 pm

With my bus, if I leave the radio faceplate on (when parked for a week) it'll drain the battery.

(I shouldn't be leaving it on anyway, on account of me living in the 'hood.)

Itinerant Air-Cooled

Itinerant Air-Cooled

Battery drain

Battery drain