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My car has recently been experiencing what I think is a parasitic battery power drain. In a span of just 24 hours, the battery voltage dropped to below 10V meaning I had to get a boost to start the car again. This happened to me twice since I didn't have time to think about troubleshooting.

I thought maybe the new battery was bust and self-discharging, so I disconnected the battery terminals and left the car overnight. I found the battery voltage dropped maybe 0.1V after 24 hours. To me that suggests the battery is probably ok - but I will try this week to bring the battery in for a test.

I also put a multi-meter in series between the battery and positive terminal (with engine off, accessories off, lights off) and I found there was a 210mAh of current draw. This current draw seems excessive to me.

I pulled fuses and found that the circuit for fuse # 36 (Central Timer, Electronic Modules) was accounting for 150mAh of current draw.

I ran out of time and did not pull any fuses or relays in the engine bay, or the relays in the interior cabin. I'll have to figure out what is causing the remaining 60mAh of current draw. I would guess the ECU and radio, which is ok.

Has anybody heard of a Central Timer Module/CTM pulling excessive current, or maybe there is something else I can check? Is there anything else on fuse #36 that could be busted causing the battery to drain?

By the way, the turn signals, rear wiper, interior lights, etc all work fine which suggests that the CTM is working ok.

Here are details on the battery:
MotorMaster GR40R/72 Battery (590 cold cranking amps)
Fully charged, engine off: ~12.5V
Engine on: ~14.5V
Age: About 2 months old


Any suggestions??? I really appreciate any help you have to offer.

wow, i guess you are on the right track and you must have a short somewhere, I think someone else was talking about a similat problem couple of weeks ago,(maybe it was you) either way, just take 1 fuse at a time and trace the wires to see where the short is.

Good luck

200mA does not seem to me to be an excessive enough drain to cause your battery to go dead within 24 hours, it likely takes at least an amp draw to kill a strong healthy battery that fast.

If you have keyless entry or factory security, the system monitoring needs the current to pick up the fob signal, and monitor the doors.

I would say that you likely have a bad cell in your battery, a multimeter has a very high resistance when you are testing voltage (so it doesn't impose a load in the circuit being tested) so while the battery is disconnected it will show very little drain, but as you leave it connected to an actual circuit it could drain the battery quite quickly. The fact that the battery voltage would drop even .1 volts in 24 hours when disconnected would point to this.

Now, if the battery is new, why did you replace the battery 2 months ago? The reason I am asking is because if you have an underlying electrical condition that would cause your old battery to fail, such as an overcharge condition, the replacement battery may have taken a couple of months to pooch (ie boiled a cell dry). 14.5 V is on the high side of the charging range, try testing the voltage while revving the engine a bit (ie 2500 RPM) to see if the voltage climbs over 14.5 . If it does you have a voltage regulator problem.

If you can get one, you might first try an alternate battery and see if the problem persists. If not = bad battery.

If it's not the battery, pull the fuse 36 when you park and see if the problem persists. If not, you've at least verified that that circuit is the source of the problem.

Then you'd have to test individual components from that circuit. You could unplug one component at a time and measure current draw across fuse 36. Hope this helps.

its a canadian tire battery, take it out, bring it to the store and they can load test in the parts department. it may jsut be a bad battery

I agree, 210mAh doesn't seem enough to drain a car battery in a day. The original battery went very dead after I didn't use the car for several weeks. I left a Bluetooth GPS receiver plugged in (oops). After that the battery was never the same and seemed to have problems starting the car. I eventually replaced the battery before an extended trip in Ottawa.

Well I was going to go today and get the battery tested but my car wouldn't start. With the battery disconnected for about 24 hours, the voltage dropped from 12.5V to about 11.7V. Sounds like the battery is toast. Once I get more time (damn work pager won't stop), I will take the battery into Crappy Tire for a test.

I wasn't paying attention to the rpm when I measured the 14.5V, but the engine was cold and had just started - probably spinning about 1,100rpm. Once I swap the battery, I will definitely check the voltage again with the engine reving a bit in case the voltage regulator is a problem.

Thanks so much for the replies.

Motomaster = gay.
get it tested

Yeah, I had a Motomaster battery go like that, but not that quickly. Probably bad right from the factory.

Ryan

So.....any outcome on this?......

I was able to stop by CanTire yesterday. The clerk at the counter didn't seem to believe me that a battery could self-discharge overnight. He tried to convince me that lead-acid batteries self discharge quickly overnight when they are disconnected from the car (what!?).

Anyways he reluctantly put the battery on the test machine and it came back as 'bad'.

So here I am with a replacement battery... fully charged I read 12.8V off the terminals. With the engine running (cold), about -10 Celcius outside, the voltage goes up to 14.75V. I also tried reving the engine, the voltage was rock solid between 800rpm to 4,000rpm.

Hopefully I'll be ok... of course due to work again, I have not tried to start it for the last 24hrs...

the battery probly had a bad cell. either way, it cmae back bad and you got a new one. just keep and eye on it. hopefully it was only a bad battery and not somehtign else like my car.

i still havent found the cause for me being on my 5th alternator in 10 months :(