somethings draining my battery

[jaydub22rc]

If my 1994 oldsmobile 98 sits without being started for more than a day the battery is completley dead and I have to jump it. It is a brand new battery so does that mean that there is a short and something is draining that battery. No lights are on nor does the radio stay on. Help please!

[MT-2500]

Originally Posted by jaydub22rc

If my 1994 oldsmobile 98 sits without being started for more than a day the battery is completley dead and I have to jump it. It is a brand new battery so does that mean that there is a short and something is draining that battery. No lights are on nor does the radio stay on. Help please!

Welcome to your first post on AF.
You will need a good volt/ohm meter that can check amp draw.
Hook it up and read amp draw.
If it has much amp draw start unpluging untill you find the short.
Also check your charging system and alternator for shorts.
MT

[BNaylor]

It sounds like you are getting parasitic drain due to an electrical component or short in the wiring. The battery has a reserve capacity rating. It could be around 120. Divide that by 4. Which equals 30 milliamps of current draw. That means you should get no more than that or the battery could be drained in a short period of time.

Connect a digital multimeter setup in the DC mA position or a 12 volt test lamp to the battery negative terminal and ground. Ignition should be to off and give it about 20 - 30 minutes run down time before checking.

As suggested start systematically disconnecting components. If the alternator checks good the easiest place to start is in the fuse boxes. Start pulling fuses and/or relays associated with the ignition and accessories circuits. Watch for changes on the meter or test lamp. Low current reading on meter or test lamp show glow dim not bright or not at all.

[Bassasasin]

Great advice there bnaylor moderator.. right to the mark.

Best bet place to start by pulling those fuses inside under dash fuse relay group one at a time and replacing them immediately and watching the light attachment setup after charging the battery.

If your a one man job you can build a setup of a extension cord with clips on one end and a 12V light on the other you can extend it all the way into the area your pulling fuses under the dash, watching for the light to go out. Remember this could also go in between the +12V terminal and the +12v connector, but it works on the negative side too, as long as installed in series at the battery.



This forum helped a guy troubleshoot his mysterous battery drain that turned out to be a antenna motor. Others have found a sunvisor vanity light still lighted when closed and similar wierd places.

Good Luck

[MT-2500]

Originally Posted by Bassasasin

Great advice there bnaylor moderator.. right to the mark.

Best bet place to start by pulling those fuses inside under dash fuse relay group one at a time and replacing them immediately and watching the light attachment setup after charging the battery.

If your a one man job you can build a setup of a extension cord with clips on one end and a 12V light on the other you can extend it all the way into the area your pulling fuses under the dash, watching for the light to go out. Remember this could also go in between the +12V terminal and the +12v connector, but it works on the negative side too, as long as installed in series at the battery.



This forum helped a guy troubleshoot his mysterous battery drain that turned out to be a antenna motor. Others have found a sunvisor vanity light still lighted when closed and similar wierd places.

Good Luck

Good idea on the test light set up but it will not work on the newer cars with 4-5 computers and modules that have power with key off and then power down a very little amp draw after so long.
The pull enough amps to keep the test light bulb lite.
The only way to check it is a volt/ohm meter that can read amps draw.
MT

[BNaylor]

Originally Posted by MT-2500

Good idea on the test light set up but it will not work on the newer cars with 4-5 computers and modules that have power with key off and then power down a very little amp draw after so long.
The pull enough amps to keep the test light bulb lite.
The only way to check it is a volt/ohm meter that can read amps draw.
MT

I agree a multimeter is the proper tool but if we want to get technical so is a Kent Moore shunt/disconnect tool as specified by GM. Now as far using a test lamp it is cheap and you can use any standard 12 volt lamp like a 1157.

It will work on late model GM cars with ECMs, PCMs, BCMs, etc. Must be connected at the negative terminal and ground and after RAP and BCM power down after 20 - 30 minutes. I've done it so I know it works. Found a bad ECM module.

And confirmed with a meter we got the parasitic drain to 12 mA which appeared to be normal for that model car.

[maxwedge]

Or a clamp on type ammeter solves all the power down issues.

[MT-2500]

Originally Posted by bnaylor

I agree a multimeter is the proper tool but if we want to get technical so is a Kent Moore shunt/disconnect tool as specified by GM. Now as far using a test lamp it is cheap and you can use any standard 12 volt lamp like a 1157.

It will work on late model GM cars with ECMs, PCMs, BCMs, etc. Must be connected at the negative terminal and ground and after RAP and BCM power down after 20 - 30 minutes. I've done it so I know it works. Found a bad ECM module.

And confirmed with a meter we got the parasitic drain to 12 mA which appeared to be normal for that model car.

Sometimes it might work.
But to get the proper power down on the pcm a test light will not do itthe proper way.
And it is hard to read mA amp draw from a test light or 1157 bulb.
On a newer car proper testing and proper equipment is in order.
I have a 02 Impala sitting in my stall.
I hooked a test light and a 1157 bulb on ground side of battery.
All it does is flash like a turn signal.
No way am i going to pulse them pcm threw a test light for 20-30 minutes hoping they will power down without burning up.
MT

[BNaylor]

Originally Posted by MT-2500

Sometimes it might work.
But to get the proper power down on the pcm a test light will not do itthe proper way.
And it is hard to read mA amp draw from a test light or 1157 bulb.
On a newer car proper testing and proper equipment is in order.
I have a 02 Impala sitting in my stall.
I hooked a test light and a 1157 bulb on ground side of battery.
All it does is flash like a turn signal.
No way am i going to pulse them pcm threw a test light for 20-30 minutes hoping they will power down without burning up.
MT

Of course the lamp will light even with low current draw such as 15 mA or less but if that is all you have it will work. I've used an 1157 and on several different cars and it does not blink. Are you sure it was wired correctly? There are two filaments in a 1157. Now I've heard of people using different type of lamps including headlamps. I'll get him to weigh-in. HotZ28.

Keep in mind this is an older '94 Olds 98 not a '02 Impala. And with the parasitic drain he has the lamp will be lit up like a Christmas tree.

Most of us DIY or tech types have a nice John Fluke (at least I do) so the issue is moot and not worth crying over.

[MT-2500]

Originally Posted by bnaylor

Of course the lamp will light even with low current draw such as 15 mA or less but if that is all you have it will work. I've used an 1157 and on several different cars and it does not blink. Are you sure it was wired correctly? There are two filaments in a 1157. Now I've heard of people using different type of lamps including headlamps. I'll get him to weigh-in. HotZ28.

Keep in mind this is an older '94 Olds 98 not a '02 Impala. And with the parasitic drain he has the lamp will be lit up like a Christmas tree.

Most of us DIY or tech types have a nice John Fluke (at least I do) so the issue is moot and not worth crying over.

10-4
The test light works on older cars but newer ones I was just pointing out it may be a problem.
I Unhooked battery key off on the 02 Impala and hooked up a 1157 tail light bulb and socket and the thing has a weak flash like a turn signal.
I will hook battery back up and try to let everything power down and then try it.
MT

[BNaylor]

Originally Posted by MT-2500

10-4
The test light works on older cars but newer ones I was just pointing out it may be a problem.
I Unhooked battery key off on the 02 Impala and hooked up a 1157 tail light bulb and socket and the thing has a weak flash like a turn signal.
I will hook battery back up and try to let everything power down and then try it.
MT

I do not disagree on car lets say from 1997 and up to present. The test lamp is not an accurate way of checking parasitic drain. I never said it was. It is just one method. I use my trusty ole Fluke when I troubleshoot auto electrical systems.

Especially when they are fully loaded with all options, BCM module, anti-theft deterrent, retained accessory power (RAP) and full content alarm systems.

But if I were stuck out in the middle of nowheres in Bum Fuk, Egypt without a multimeter I think I would highly consider using any 12 volt lamp off the car.

HotZ28 has some interesting info on the subject. We've had a lot of discussions on parasitic drain in just about all the forums with some interesting stories. Most members wind up giving up and taking it to a dealer or mechanic with electrical knowledge and capability.

[HotZ28]

If you want some equipment especially designed for this type of testing, you might want to consider the following.
(A little pricey for the DIY’s, or one time user)!
Battery Drain Tester w/ Memory Saver $185.00
Low Current Probe / Digital Multimeter $139.00
Low Current Probe $125.00

The device that controls the courtesy lights and retained accessory power (RAP) is the body control module (BCM). The BCM will have the most parasitic draw of any electrical component and may explain the battery drain if it is defective. Also, other components (see below), could cause the problem. The RAP, is part of the battery protection circuit and if working normally, it will shut down all power to accessories after 10 minutes from the time the driver exits the car, or when the lock is pressed on the remote.

Now, several other items that come to mind that are notorious for causing battery drain are the ELC, power radio antenna (check to be sure it goes all the way down), glove box light, power door locks, blower control module, and of course the PCM. The following items are considered normal drain, on most late model cars and the total should not be over 19.85 mA according to the service manual.

Adaptive Lamp monitor = 0.5 - 1.0 mA
HVAC Programmer = 0.5 - 0.75 mA
Gages Cluster = 4.0 - 6.0 mA
Oil level module = 0.1 mA
Radio = 7.0 - 8.5 mA
Amplifier = 1.8 - 3.5 mA

Total = 13.9 to 19.85 mA = 0.002 A max.

Several months ago, I conducted some test on two Buicks, just to satisfy my curiosity as to how accurate the “test light” procedure would be. My main objective was to determine how many mA would be required to light the bulb and then determine how bright the bulb would be at various mA draws.

First, before I conducted this test, I used a 12V portable light with a built in cigarette plug socket. I plug the male end into the 12V light battery source and the other male plug into the cars cigarette lighter plug. (You can also do this with a 9V battery wired to a male cigarette plug) This provides a memory saver feature that protects the vehicle’s computer memory, preserving stored fault codes, drivability parameters & programmed electronic settings such as clock, radio, seat position, etc. The vehicle computer remains in "sleep mode," allowing correct parasitic drain to be measured.

When I tested the first car, (no problems with drain) it drew ~ 11.50 mA. This was with the DVOM in series between the battery – post and the negative cable, with all systems off. The other car was within .60 mA of the first, so I concluded that both were without abnormal drain. When using the 1156 test bulb (I prefer the 1156 bulb over 1157 since it only has one filament) in the same manner as the DVOM, the light was off. I turned on the ignition switch, the light did glow, however, not full bright. (This is telling me that the ignition components are drawing current through the test bulb)

Now, if there was an abnormal drain, (+ 25 mA) the test light will light somewhat brighter, but may not be full bright. (Brightness is directly proportional to drain) Always make sure the key is off and the doors are closed, before conducting this test.

If the light is lit (bright), you can assume that there is abnormal drain and you are now ready to start pulling fuses/relays one at a time while watching for the light to go out (or dimmer). Also, you want to start with the main cockpit fuses first, but don't forget the other two fuse/relay panels.

In conclusion, I was able to determine several things of interest concerning the “test light” procedure.

• It does work, if you know how to read the bulb.
• Bulb would not light with less than 22 mA
• The more abnormal the draw, the brighter the light.
• I could simulate voltage drain by “creating drain” i.e. trunk light, glove box ignition switch and watch the bulb get brighter with each additional drain.
• 50+ mA gives substantial light from the test light! I would consider anything over 30 mA to be excessive drain.