Jeep GC- battery keeps dying- 100ma draw too mcuh?

I've had to jump my 2001 Jeep GC many times in the last 6 weeks. Battery and alternator check out as okay. I started looking for battery drain. I tested a 90-100ma draw with ignition and everything else powered off. Is this too high? From what I read, this wouldn't drain the battery in a matter of days.

Reply to
Mike C
Loading thread data ...

A constant 100mA is too much, but I agree that it would take atleast several days for it to drain a typical battery down. Leave your ammeter on for about 10 minutes and see if the current ever drops down below 50mA. What typically happens is that several of the major ECMs are still communicating/powered up after the key is turned off. They will power down one at a time until your draw is very low, like 25mA or so. It can take from around 2 to 10 minutes, so give it time.

If you still read a constant 100mA then I would start unplugging fuses and look for a drop. Start with any aftermarket addon stuff like radio or alarm.

Toyota MDT in MO

Reply to
Comboverfish

I did take several readings, even the next morning after the car had been off and they all read 90-100ma. I pulled the power outlets which I have an mp3 player connected to (mounted under drivers seat), but that didn't do it. Would the alarm be fused? I am suspicious of that.

Reply to
Mike C

Are you using a DVOM set to mA in between a battery post and it's terminal, or an inductive clamp style ammeter? Are you certain it is accurate?

Yes, the alarm, if aftermarket, should be fused. Look for the alarm module usually found under the dash, and there will be several inline fuse holders wired to it. Pull all of these fuses.

Keep in mind you need to keep a DVOM style ammeter in place at all times during the test. If you break it's connection the ECMs will have to go through their power cycle again when you hook it back up, and all capacitors will have to recharge. If your meter automatically powers down (a common battery saving feature) then it may break the connection that way as well.

Toyota MDT in MO

Reply to
Comboverfish

It is a DVOM in betwen battery post and battery wire. I did leave it all night (meter in place) and had the same reading this morning, so the ECMs shouldn't be a factor.

Reply to
Mike C

Good. If it is a decent DVOM it should be very accurate at reading amperage. Start pulling fuses.

Toyota MDT in MO

Reply to
Comboverfish

I looked at the negative ground to the engine and it doesn't look corroded. I have heard that casuing problems. Maybe I will get in there and disconnect it and inspect it.

Reply to
Mike C

Besides the draw, dirty connections on the battery cable ends, especially the one that goes to the body can and do cause your symptoms. They can get to a point of needing a boost each morning but working all day idea.

With the dirty connections, the battery only gets a light charge in it which won't last long sitting.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Reply to
Mike Romain

Some of these cables corrode internally and you may not see it unless you can skin back the rubber and examine. And, battery cables and their contact points also need to be clean on both ends for them to work correctly.

100 ma is a little high, but as was previously posted, this should last several days.

Try removing the wire that goes from alternator to battery and see if the drain goes away. If so, maybe there is a high resistance short in a diode in the alternator. This will not only decrease your ability to charge, but can also give a discharge path to ground. ( If your normal static drain is 50 ma, then your additional resistance path to ground would be about 270 ohms)

Batteries that are more than a year or two old may also fool you. Have you had it checked? Is the electrolyte up to level? Poor battery test procedures can often give a clean bill of health to a crappy battery.

Reply to
hls

The battery is less than a year old. The place I bought it tested it and said it was good. I am wondering if it could test good, but not hold the charge over a period of time (obviously, they are just testing it for 15 minutes).

I am wondering if this is my scenario: Battery drain is draining the battery. I frequently take very short trips (3-5 miles). When I don't use the car for several days, battery drains=dead battery and causes car not to start. I jump, run 15 minutes and take my short trip. Since battery doesn't fully charge on these short trips, 2 days later battery drain zaps what little charge is in battery. Since the problem seems intermittant, I think it could be directly related to how long I am running the car. On short trips, the battery isn't fully charging.

Reply to
Mike C

Bingo, you have found the problem. The undercharging of your battery from the short trips and inactivity causes a slow buildup of lead sulfate which is robbing your battery of capacity that will not necessarily show up on a conductive battery tester. Please see Section 16 in the Car and Deep Cycle Battery FAQ on

formatting link
on how to identify sulfation problems and how to cure some of them.

The best way to prevent sulfation is to keep the battery fully charged. If this is not practical, then periodically recharge your battery with an external battery charger matched to your battery type. Section 9 has information of charging and chargers and Section 7.1 has information of battery types.

Kindest regards,

BiLL.....

Reply to
Bill Darden

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.