D2 Battery Drain at .6amps

[Cozy41EF]

Okay, happened once last week, drove the truck to retrieve a VW bug for a friend, used the Disco to jump the bug, then drove the bug on a car hauler and used the Disco to pull it home. Week later went out to drive the Disco and the battery was dead. Like .3vDC dead. Key opened the drivers door, used jumper cables and a spare battery and the Disco started right up. Battery voltage with truck running was 14.3vDC. Drove truck 20 minutes, then hooked up battery charger to top it off. Few hours later drove truck for 30 minutes, seemed fine.

Then, next morning, battery dead, again. Read several threads about alternator causing drains. Pulled battery and charged it, found the battery had 4 cells low on water, two of which were very low, added about 2 cups of water total. Charged the battery again, then used a thread from PT and connected an amp meter between the neg terminal and the neg batteru cable. I got a steady .6 amp drain. Removed the alt lead from the distribution box under the hood, no change, removed fuses and the only thing that changed was the middle large fuse that connects the fuse box in the cab. Went to the cab and started removing fuses and got no change on any of them. Well, I got an occassional .1 amp change but the discharge stayed about .5 to .6 amps. Removed meter and connected battery. Checked all of the doors shut, no lights on, no nothing. Locked, unloncked, started, shut off. Removed batt cable and hooked up meter again, got .1 amp which then went to about 30 miliamps as it went to sleep.

Truck sat overnight started right up. Waited two days started again. It's been 2 weeks and runs great, no problems.

I read an alternater causes a 4 amp drain that will kill a battery in a few hours, but .6 amps takes overnight. What on a D2 draws .6amps? Could it be a door actualter hanging up? SLS actuator? Whatever it was stopped, but of course could return anytime.

So, my question to the gurus, is what on D2 draws .5 to .6 amps that sticks or hangs or whatever?

 

[lacrits68]

Hello!

Your alternator has failed! Or some of you diodes in the alternator has failed, letting current drain "wrong" way tru alternator!

ALTERNATOR DIODE FAILURES

One of the most common causes of charging problems is the failure of one or more diodes in the alternator. Alternators have six diodes (three negative and three positive) that convert the alternating current (AC) to direct current (DC). They are called a diode trio because each negative diode is paired with a positive diode.

When the engine is running, charging current from the alternator flows through the diode trio via the BAT (B+) connection on the back of the alternator. A little current also flows through the charging light indicator circuit. On GM alternators, the indicator light circuit is terminal 1. On European alternators, the indicator light circuit is usually called 61 or D+. On Asian alternators, it is usually labeled L. This terminal leads to the ground side of the alternator warning light. When the alternator is charging, the diode trio supplies voltage to the ground side of the indicator light. This offsets the battery voltage applied to the positive side of the light, causing the light to go out once the engine starts. If the alternator stops charging, current flows though the light circuit from the positive side causing the charging system warning light to come on.

If one of the diodes fails, it may cause the charging system indicator light to glow dimly. If two or more diodes fail, the light will get brighter. At the same time, the feedback current from the diode trio will reduce the alternators ability to produce current. So the more diodes that fail, the less power the alternator will generate.

A bad connection or open circuit between the alternator output terminal and the positive battery terminal will force the charging current to follow a parallel route through the diode trio and out of the alternator. This heavier than normal current flow through the diodes will cause them to overheat and fail. Consequently, if you have replaced an alternator before because of bad diodes, and the replacement fails for the same reason, there is likely a bad connection or open circuit between the alternator BAT (B+) terminal and the positive side of the battery circuit. Do a voltage drop test to check the entire circuit.

http://www.aa1car.com/library/charging_checks.htm


easily tested by disconecting alternator from battery!

my 2 cents...!

//Jan

 

[Plain2000DII]

How old is your battery? Weak batteries can hang on for ever, until they just give up. Typically if my battery is 4 or 5 years old and it starts acting up, it's time to replace. (after a stop by napa to have the circuit checked)

 

[Cozy41EF]

I replaced the alternator almost 2 years ago when it failed, the batt light came on and output voltage running was only 12.2 volts. Bought a used one from Will and had no problems untill now.

I disconnected the large lead and the sense wire and the drain was still at .6 amps. I don't think it's the alternator.

Battery is about 4 years old, was low on water but seems ok now that I filled it. I also installed a battery from the boat to test it, still had .6 amps.

I have a battery load tester and both batteries checked good.

I have no voltage drop between the alternator terminal and the positive battery terminal.

It's also been about two weeks since I had the issue, and have had no problems since. It makes me think a door lock actuator or a SLS relay somehow hung up.

 

[lacrits68]

Hi!

OK!

Why not try to pull out one fuse att time and rule thing out systematicly??

//Jan

 

[lacrits68]

Hi!

A bit curious....did you solve your problem?

cheers

Jan

 

[Cozy41EF]

Its been about a month now, and have had no more problems. I drive the truck every few days, and have let it set a week and have had no problems.

I swear I think it was a door lock actuator hung up, or something similear. I initialy thought it might have been the SLS rear air bags, but again, no problems now. No drain.

 

[group captain mandrake]

My '99 has an intermittant drain. Years ago it was my daily driver and every now & then it would have a dead battery overnight for no apparent reason. Whenever I checked the draw it was something like 20 milliamps. I could never catch it drawing much. These days I don't drive it very often. But maybe 3 or 4 times a year it will have a dead battery when it shouldn't. It is not a battery issue as I started out with Optima Red-Tops, had about three of them replaced under warranty, then put one of my marine Die Hards in it, and now that I don't drive it much, it has an Interstate in it. It has done the "dead battery overnight for no apparent reason" with lots of different batteries in it.
This truck, for some wierd reason, just has a draw every now and then that I haven't been able to catch with my Fluke hooked up.

 

[DarylJ]

Its been about a month now, and have had no more problems. I drive the truck every few days, and have let it set a week and have had no problems.

I swear I think it was a door lock actuator hung up, or something similear. I initialy thought it might have been the SLS rear air bags, but again, no problems now. No drain.

I recently had something similar happen and realized that my window ECU was not turning off after the 45 second timeout or a door opening as it should. I could get back in the truck in the morning and the windows would still operate without using the key.

This has gone away, but will likely come back. I haven't diagnosed it much further, but considering all of the window ECU issues (cold solder joints) I may just pop that out and reflow everything as a first measure.

 

[listerdiesel]

You need to get a handle on what the issues are by working out how long different current flows will take to flatten your battery, and then try and pinpoint suitable devices that would cause the drain..

Assuming a 72AH battery:

20mA - 3600hrs or 150 days
600mA or 0.6A - 120 hours or 5 days
1A - 72 hours or 3 days
5A - 13.8 hours
10A - 6.4 hours
20A - 2.6 hours

Aerial amplifiers take a few milliamps, door solenoids take more than an amp, probably 2-3A for the short period of operation.

So you can see that small discharge rates need a fair bit of time to run a battery down, and also note that the faster you discharge a battery, the less returned capacity you will get from it.

Peter