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Posted: 2/9/2006 7:29:05 PM EDT
My car is a '95 BMW M3. It recently has aquired a parasitic load on the electrical system. The battery drains after a 5 or 6 or so hours. Im pretty certain that the load is substantial. I thought that the battery might be old (it was 6 years old) and maybe had a short in it, so I got a new one, an Optima cell battery. I installed the new battery, but the drain is still there. So, I guess it wasnt the battery. The car functions fine, everything works just great....its just something draining my battery.

I removed all the fuses and the drain is still there

Anybody know of any tests that I can do? I have a Fluke mutilmeter.
Link Posted: 2/9/2006 7:35:41 PM EDT

Originally Posted By gaspain:
My car is a '95 BMW M3. It recently has aquired a parasitic load on the electrical system. The battery drains after a 5 or 6 or so hours. Im pretty certain that the load is substantial. I thought that the battery might be old (it was 6 years old) and maybe had a short in it, so I got a new one, an Optima cell battery. I installed the new battery, but the drain is still there. So, I guess it wasnt the battery. The car functions fine, everything works just great....its just something draining my battery.

I removed all the fuses and the drain is still there

Anybody know of any tests that I can do? I have a Fluke mutilmeter.



Daaang, removed all the fuses? That sucks, usually I recommend using the ammeter setting and removing one fuse at a time until you at least isolate the circuit causing the drain. You may have a circuit on a fusible link causing the drain then, or one that is hard wired. Any aftermarket junk on the car, stereos, alarms, etc? If so look there first. If not then get a good schematic (most likely a factory manual) and start isolating systems protected by fusible link one at a time. Sounds like a real pain in the arse, a mechanic is going to charge you an arm and a leg to isolate this one.
Link Posted: 2/9/2006 7:35:58 PM EDT
That is a pretty strong drain... I would check your alternator and starter. Auto Zone can check the alternator, and if you can pull the wire off your starter after a full charge and you don't get the drain, you will know if the problem is there.
Link Posted: 2/9/2006 7:40:15 PM EDT
Link Posted: 2/9/2006 7:46:59 PM EDT
I suspect that it is the battery. The reason is that under the hood heat kills batteries, no matter how good they are. But I would have the battery and electrical system checked out just to be sure everything is good.
Link Posted: 2/9/2006 8:27:51 PM EDT
[Last Edit: 2/9/2006 8:28:33 PM EDT by samsong]

Originally Posted By gaspain:
My car is a '95 BMW M3. It recently has aquired a parasitic load on the electrical system. The battery drains after a 5 or 6 or so hours. Im pretty certain that the load is substantial. I thought that the battery might be old (it was 6 years old) and maybe had a short in it, so I got a new one, an Optima cell battery. I installed the new battery, but the drain is still there. So, I guess it wasnt the battery. The car functions fine, everything works just great....its just something draining my battery.

I removed all the fuses and the drain is still there

Anybody know of any tests that I can do? I have a Fluke mutilmeter.



samsong here, multi-year BMW owner to the rescue. Wife's 325I ('89-type) used to love to chew up batteries in just the same fashion, although it was more insidious - it would take nine months to one year to do one in. We tried turning off interior lights by removing bulbs, replacing batteries, etc.

Nothing worked.

I looked at the negative battery cable, and there was corrosion there. I pointed it out to my pin-headed BIL, who is a 20-year Volvo/Caddy mechanic, and he shot my theory down. A year goes by and we lose her battery again, and I make him replace the cable; when he takes it off, it falls apart. Once replaced, the system works perfectly, and we've gone 2+ years w/o electrical failure.

Then, I read it in an issue of Roundel, and they report that the problem is very common.
Link Posted: 2/9/2006 8:42:18 PM EDT

Originally Posted By warlord:
I suspect that it is the battery. The reason is that under the hood heat kills batteries, no matter how good they are. But I would have the battery and electrical system checked out just to be sure everything is good.

\

the battery is in the trunk
Link Posted: 2/9/2006 8:45:24 PM EDT

Originally Posted By samsong:
I looked at the negative battery cable, and there was corrosion there. I pointed it out to my pin-headed BIL, who is a 20-year Volvo/Caddy mechanic, and he shot my theory down. A year goes by and we lose her battery again, and I make him replace the cable; when he takes it off, it falls apart. Once replaced, the system works perfectly, and we've gone 2+ years w/o electrical failure.



MECHANIC'S RULE #27: If you can't explain how your repair "fixed" the problem, it's not a "fix".

So...Care to explain how a corroded battery cable could drain a battery?
Link Posted: 2/9/2006 8:57:03 PM EDT
My moms Mercedes was doing something similiar some years ago. Mercedes replaced something like 5 batteries, 6 solenoids and a few various other parts and never solved the problem. Dad got fed up with it, if you have an engineer for a Dad you understand what "fed up" means, and spent a weekend testing the load on every circuit in the car. He found a bad relay going to the clock. It was drawing like 5x normal juice or wasn't opening when it was supposed to or something like that. He talked to tech. Tech replaced relay. Problem fixed. Any mechanic wil tell you electrical problems are a bitch to find.
Link Posted: 2/9/2006 8:59:04 PM EDT

Originally Posted By Mojo_Jojo:
That is a pretty strong drain... I would check your alternator and starter. Auto Zone can check the alternator, and if you can pull the wire off your starter after a full charge and you don't get the drain, you will know if the problem is there.




BINGO You win.
Link Posted: 2/9/2006 9:00:57 PM EDT

Originally Posted By gaspain:

Originally Posted By warlord:
I suspect that it is the battery. The reason is that under the hood heat kills batteries, no matter how good they are. But I would have the battery and electrical system checked out just to be sure everything is good.

\

the battery is in the trunk


Still, lead/suphuric acid cells will go through a process called "sulphation" where the plates will no longer able to store electricity. Over time, the battery won't hold a charge and you've got to buy a new one.
Link Posted: 2/9/2006 10:12:07 PM EDT
I had that problem in my 1990 Laser. Turned out to be a short at the pushbutton switch on the door frame that turns the inside light on when you open the door.

Have fun finding it....
Link Posted: 2/9/2006 10:18:58 PM EDT
[Last Edit: 2/9/2006 10:19:30 PM EDT by KS_Physicist]

Originally Posted By Skibane:

Originally Posted By samsong:
I looked at the negative battery cable, and there was corrosion there. I pointed it out to my pin-headed BIL, who is a 20-year Volvo/Caddy mechanic, and he shot my theory down. A year goes by and we lose her battery again, and I make him replace the cable; when he takes it off, it falls apart. Once replaced, the system works perfectly, and we've gone 2+ years w/o electrical failure.



MECHANIC'S RULE #27: If you can't explain how your repair "fixed" the problem, it's not a "fix".

So...Care to explain how a corroded battery cable could drain a battery?



I had a battery that kept dying for no apparent reason, didn't seem to want to hold a charge. Ultimately, I bought a new battery, which worked for a couple of weeks. Then it started dying--despite the IOD test showing (much) less than 500 milliamps draw.

On closer inspection, the block-end of the negative battery cable had corroded inside the insulation, and was hanging on by a couple of green remnants. It broke off in my hand when I grabbed it to see how bad it was. The car had been running with only a single, 10 gauge ground wire to the radiator support panel. At high current, this is a significant resistance, and resulted in voltage drop and insufficient charge in daily driving to replenish the battery. An otherwise good battery seemed to die on me every few days.

I cut off the corroded cable and spliced in a new piece, using welding cable, installed properly with solder, liquid electrical tape, and shrink wrap. After that fix was done, the charging/discharge problem went away completely.

Jim
Link Posted: 2/9/2006 10:28:41 PM EDT

Originally Posted By Mojo_Jojo:
That is a pretty strong drain... I would check your alternator and starter. Auto Zone can check the alternator, and if you can pull the wire off your starter after a full charge and you don't get the drain, you will know if the problem is there.



I vote alternator.
Link Posted: 2/10/2006 1:53:26 AM EDT
My inlaws bought a new Kia minivan that had the same problem. 4-5 hours it would be dead as a hammer. numerous trips to the dealer and a half dozen batteries they got fed up and went to another dealer across town.

They checked it out and found a bad seat motor. Good luck on finding the problem, electrical problems can be a PITA....
Link Posted: 2/10/2006 2:35:59 AM EDT
Its the new tracking device, sorry, we'll get a lower powered one on the car next time you take it to the shop.

Kharn
Link Posted: 2/10/2006 3:10:08 AM EDT
Tag. I'm currently on battery number two on Mrs. Slackers Hyundai. Takes two days of not running for it to die. I'll be removing fuses this weekend, one at a time. I'm betting its the starter or "accessories". After hearing about the grounding wires falling apart, I'll also trace it.
Link Posted: 2/10/2006 3:17:38 AM EDT
I'd look at the alternator too.

Quick at-home check is to put your hand on it a couple hours after you shut the car off.

That much of a drain will generate a lot of heat.
You should be able to feel an alternator warmer than it should be.
Yes, Autozone can diagnose this for you, and it would be hard to believe
you don't live within sight of one as they are everywhere, but at least
this is something you can do yourself as a quick check.


Link Posted: 2/10/2006 3:25:04 AM EDT
My friend just recently had the same problem.

After having driven him and the mechanic nuts for a few days, it was found that the trunk light was remaining on even when the trunk was closed, causing the drain.
Link Posted: 2/10/2006 3:54:59 AM EDT
unhook the battery cable and put an ammeter between the battery post and battery cable. that will tell you how many amps you are drawing. make sure you doors are closed so the interior lights are out of the circiut also if you trunk or hood has lights you might want to unplug them. how many amps are you pulling?
Link Posted: 2/10/2006 3:58:12 AM EDT
Relay
Link Posted: 2/10/2006 6:11:31 AM EDT
no other way to find it. Get a voltmeter that reads amps, hook it up and start pulling fuses, then work on all other circuits, Wiring schematic may be helpful. could also be starter or alternator, but you know this.
Link Posted: 2/10/2006 6:54:09 AM EDT
HI there gaspain, did you try unplugging that E Z bake oven you installed last year? those things can use alot of power up.
Link Posted: 2/10/2006 7:18:00 AM EDT
Dude,

See if you have something in your cigarette lighter like a penny, I keep my change in my ashtray and it happened to me once.

My neighbor also had a similar problem. Turned out that the last repair he had was assembled incorrectly and a wire was pinched when his car was put back together. I would look at the last thing repaired.

Link Posted: 2/10/2006 7:21:23 AM EDT
Sounds like it is turning British on you.
Link Posted: 2/10/2006 8:39:53 AM EDT
Most cars shut off the cig lighter when the car is off.
If you are sure you are pulling amps when the car is off, then the neg cable is not the answer.
Did you pull fuses and relays inside and outside? Typically you have a set in the dash, and a set in the engine compartment.
I cannot think of anything not fused or relay protected that pulls power, unless you put in something aftermarket and they wired it directly to the battery.
Link Posted: 2/10/2006 8:42:20 AM EDT
[Last Edit: 2/10/2006 8:43:55 AM EDT by The_Reaper]

Originally Posted By Andrewh:
Most cars shut off the cig lighter when the car is off.



I'd never seen any car do that until I met my wife's Honda.



I had a penny fall into the cig lighter of my '79 Bonneville several years.

It shorted things out such that when I honked the horn, the dome light came on.
But it never ran the battery down. Wierd.

Link Posted: 2/10/2006 9:01:39 AM EDT
[Last Edit: 2/10/2006 9:07:24 AM EDT by FITTER]
It COULD be any of the above-mentioned problems, but you need to start with the basics. Assuming that you don't have a charging problem (does your car have gauges or idiot lights?), the first thing you need to do is to check for power draw at the battery with the key off.

Remove the negative cable at the battery and connect a non-powered test light between the battery terminal and the removed cable clamp. If it lights up, it means you have "draw" in one of the circuits. Start pulling fuses one by one until the light goes out... that should send you in the right direction.
BTW, just having the door open will indicate a draw.

It could be a trunk light that stays on, as someone said, or a glove-box light, engine compartment light, LIGHTED SUN VISOR MIRROR, door switch, etc. Once you've eliminated the possibility of a draw, you should consider battery condition and charging system problems. Green corrosion somewhere on a hot wire is often a good clue, especially at a factory splice. This can be hard to spot, as it is often hidden inside the harness... but first things first.

edited to clarify
Link Posted: 2/10/2006 9:08:54 AM EDT
Not to hijack this thread or anything, but I have a related electrical question. My 1996 Oldsmobile Cutlass Ciera (shutup, its still my car from college. ;) ) has a weird problem. When ever I press my brakes, all of my lights getting dimmer- my head lights, my dome light, etc. Any idea what is causing this? It happens even with my radio off.
Link Posted: 2/10/2006 9:11:43 AM EDT

Originally Posted By Paul:
Check any aftermarket stuff like alarms, CB radios, and car stereos and amplifiers.




Don't forget to look for secretly installed gov't tracking devices!!
Link Posted: 2/10/2006 10:05:41 AM EDT

Originally Posted By libertyof76:
Not to hijack this thread or anything, but I have a related electrical question. My 1996 Oldsmobile Cutlass Ciera (shutup, its still my car from college. ;) ) has a weird problem. When ever I press my brakes, all of my lights getting dimmer- my head lights, my dome light, etc. Any idea what is causing this? It happens even with my radio off.


Well you are, but stuff it in neutral when you hit the brakes. If it brightens up, then your voltage reg or altenator is not keeping up at lower rpms when you brake.
Or if it doesn't brighten up, you may have a short somewhere drawing a lot of power when you apply the brakes.

the only two things happening are your car is slowing down, and 2 lights go to lighting up both filiments, and the 3rd brake light turns on.
Link Posted: 2/10/2006 6:37:42 PM EDT

Originally Posted By KS_Physicist:

I had a battery that kept dying for no apparent reason, didn't seem to want to hold a charge. Ultimately, I bought a new battery, which worked for a couple of weeks. Then it started dying--despite the IOD test showing (much) less than 500 milliamps draw.

On closer inspection, the block-end of the negative battery cable had corroded inside the insulation, and was hanging on by a couple of green remnants. It broke off in my hand when I grabbed it to see how bad it was. The car had been running with only a single, 10 gauge ground wire to the radiator support panel. At high current, this is a significant resistance, and resulted in voltage drop and insufficient charge in daily driving to replenish the battery. An otherwise good battery seemed to die on me every few days.

I cut off the corroded cable and spliced in a new piece, using welding cable, installed properly with solder, liquid electrical tape, and shrink wrap. After that fix was done, the charging/discharge problem went away completely.



Yep, that "fix" definitely passes the Mechanic's Stink Test for a battery that goes dead after several days of driving...

...but not for a battery that goes dead after 5-6 hours of sitting idle!
Link Posted: 2/10/2006 7:56:50 PM EDT

Originally Posted By stoney-dog:
unhook the battery cable and put an ammeter between the battery post and battery cable. that will tell you how many amps you are drawing. make sure you doors are closed so the interior lights are out of the circiut also if you trunk or hood has lights you might want to unplug them. how many amps are you pulling?



One thing to note is that some cars run various checks once in a while after the engine is shut off. In Neons, for instance, the PCM will occasionally power up the O2 sensor heaters for a few minutes after shutdown to do a diagnostic. This would show as a pretty heavy drain--but would shut off within a few minutes.

Jim
Link Posted: 2/10/2006 8:02:28 PM EDT

Originally Posted By Skibane:

Originally Posted By KS_Physicist:

I had a battery that kept dying for no apparent reason, didn't seem to want to hold a charge. Ultimately, I bought a new battery, which worked for a couple of weeks. Then it started dying--despite the IOD test showing (much) less than 500 milliamps draw.

On closer inspection, the block-end of the negative battery cable had corroded inside the insulation, and was hanging on by a couple of green remnants. It broke off in my hand when I grabbed it to see how bad it was. The car had been running with only a single, 10 gauge ground wire to the radiator support panel. At high current, this is a significant resistance, and resulted in voltage drop and insufficient charge in daily driving to replenish the battery. An otherwise good battery seemed to die on me every few days.

I cut off the corroded cable and spliced in a new piece, using welding cable, installed properly with solder, liquid electrical tape, and shrink wrap. After that fix was done, the charging/discharge problem went away completely.



Yep, that "fix" definitely passes the Mechanic's Stink Test for a battery that goes dead after several days of driving...

...but not for a battery that goes dead after 5-6 hours of sitting idle!



The evidence when I had the bad cable DID appear to be a "several hours of sitting = dead" issue. It would run fine for days with no serious problems, then I'd park it, come back and it wouldn't be able to turn the engine over. Even though it was a problem that was progressively worse over the course of several days of normal driving, it would appear to come on fairly suddenly, because of the sudden appearance of the no-start condition. (Trying to pull 100+ amps of current through a single 10 gauge wire causes such a voltage drop that it would simply de-energize the starter solenoid.)

If you put the battery on a charger, and bring it up to a confirmed full charge state, and it STILL dies six hours later, THEN you can be reasonably sure it's a current draw problem. Or if you use an ammeter to measure the current while the car is off.

Jim
Link Posted: 2/10/2006 9:25:57 PM EDT

Originally Posted By Skibane:

Originally Posted By samsong:
I looked at the negative battery cable, and there was corrosion there. I pointed it out to my pin-headed BIL, who is a 20-year Volvo/Caddy mechanic, and he shot my theory down. A year goes by and we lose her battery again, and I make him replace the cable; when he takes it off, it falls apart. Once replaced, the system works perfectly, and we've gone 2+ years w/o electrical failure.



MECHANIC'S RULE #27: If you can't explain how your repair "fixed" the problem, it's not a "fix".

So...Care to explain how a corroded battery cable could drain a battery?



The poor conduct to ground didn't kill the battery, the poor conduct to ground prevented the battery from recieving all the charge the alternator was providing to it. The constant load on the battery from the other electrical systems on the car wore it out.
Link Posted: 2/11/2006 12:08:20 AM EDT

Originally Posted By Mojo_Jojo:
That is a pretty strong drain... I would check your alternator and starter. Auto Zone can check the alternator, and if you can pull the wire off your starter after a full charge and you don't get the drain, you will know if the problem is there.



+ 1 Gotta hunch he's right. Remember, check the easy, and obvious stuff first.
Link Posted: 2/11/2006 2:16:01 AM EDT

Originally Posted By samsong:

Originally Posted By gaspain:
My car is a '95 BMW M3. It recently has aquired a parasitic load on the electrical system. The battery drains after a 5 or 6 or so hours. Im pretty certain that the load is substantial. I thought that the battery might be old (it was 6 years old) and maybe had a short in it, so I got a new one, an Optima cell battery. I installed the new battery, but the drain is still there. So, I guess it wasnt the battery. The car functions fine, everything works just great....its just something draining my battery.

I removed all the fuses and the drain is still there

Anybody know of any tests that I can do? I have a Fluke mutilmeter.



samsong here, multi-year BMW owner to the rescue. Wife's 325I ('89-type) used to love to chew up batteries in just the same fashion, although it was more insidious - it would take nine months to one year to do one in. We tried turning off interior lights by removing bulbs, replacing batteries, etc.

Nothing worked.

I looked at the negative battery cable, and there was corrosion there. I pointed it out to my pin-headed BIL, who is a 20-year Volvo/Caddy mechanic, and he shot my theory down. A year goes by and we lose her battery again, and I make him replace the cable; when he takes it off, it falls apart. Once replaced, the system works perfectly, and we've gone 2+ years w/o electrical failure.

Then, I read it in an issue of Roundel, and they report that the problem is very common.


a Your issue was the bad negative cable was not allowoing the battery to charge, this guys issue is the battery draining down over night, completely differnt symptom from yours....
Link Posted: 2/11/2006 2:18:43 AM EDT

Originally Posted By MissileCop:
My friend just recently had the same problem.

After having driven him and the mechanic nuts for a few days, it was found that the trunk light was remaining on even when the trunk was closed, causing the drain.


a trunk light will not drain a new battery over night....
Link Posted: 2/11/2006 2:48:12 AM EDT
If your brand new Optima took a dump in several hours, you can narrow your search to something with a big wire going to it! I can tell you for sure that this won't be a small lamp, though it could be a fairly hard short such as a wire pinched to a ground point...at the discharge rate you described this problem will cure itself over time!

Good Luck
Bryan
Link Posted: 2/11/2006 3:01:35 AM EDT
Link Posted: 2/11/2006 4:01:31 AM EDT
Not all circuits have fuses. Headlamps have self resetting circuit breakers. There may be more in your bimmer.

Link Posted: 2/11/2006 4:06:02 AM EDT

Originally Posted By libertyof76:
Not to hijack this thread or anything, but I have a related electrical question. My 1996 Oldsmobile Cutlass Ciera (shutup, its still my car from college. ;) ) has a weird problem. When ever I press my brakes, all of my lights getting dimmer- my head lights, my dome light, etc. Any idea what is causing this? It happens even with my radio off.


sounds like a wire is getting pinched when you depress the brake
Link Posted: 2/11/2006 4:08:40 AM EDT

Originally Posted By N_FL_Mountaineer:
If your brand new Optima took a dump in several hours, you can narrow your search to something with a big wire going to it! I can tell you for sure that this won't be a small lamp, though it could be a fairly hard short such as a wire pinched to a ground point...at the discharge rate you described this problem will cure itself over time!

Good Luck
Bryan


doh!
Link Posted: 2/11/2006 4:44:55 AM EDT
i had a problem with an aftermarket alarm and starter system. perhaps the alarm pins
Link Posted: 2/12/2006 12:41:35 AM EDT

Originally Posted By JFP:

Originally Posted By samsong:

Originally Posted By gaspain:
My car is a '95 BMW M3. It recently has aquired a parasitic load on the electrical system. The battery drains after a 5 or 6 or so hours. Im pretty certain that the load is substantial. I thought that the battery might be old (it was 6 years old) and maybe had a short in it, so I got a new one, an Optima cell battery. I installed the new battery, but the drain is still there. So, I guess it wasnt the battery. The car functions fine, everything works just great....its just something draining my battery.

I removed all the fuses and the drain is still there

Anybody know of any tests that I can do? I have a Fluke mutilmeter.



samsong here, multi-year BMW owner to the rescue. Wife's 325I ('89-type) used to love to chew up batteries in just the same fashion, although it was more insidious - it would take nine months to one year to do one in. We tried turning off interior lights by removing bulbs, replacing batteries, etc.

Nothing worked.

I looked at the negative battery cable, and there was corrosion there. I pointed it out to my pin-headed BIL, who is a 20-year Volvo/Caddy mechanic, and he shot my theory down. A year goes by and we lose her battery again, and I make him replace the cable; when he takes it off, it falls apart. Once replaced, the system works perfectly, and we've gone 2+ years w/o electrical failure.

Then, I read it in an issue of Roundel, and they report that the problem is very common.


a Your issue was the bad negative cable was not allowoing the battery to charge, this guys issue is the battery draining down over night, completely differnt symptom from yours....



Don't assume the battery ever made it up to a full charge, then a minor drain would draw it down enough to cause problems in a few hours.

Things that have bit me over the years (although never in just a few hours) clocks, tailgate ajar light on the dashboard when the tailgate was fine but the switch was bad.

Do you have an under the hood light that has a mercury switch that turns it on when you put the hood up" I've seen mechanics that bend them down to get better light from them and then they don't go out. Those can do it over night
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