Parasitic Battery Drain!

[gadget73]

Just so you know, most clamp-on ammeters are for AC only, not DC like a car uses. If thats what you had, its never going to give a useful reading in an auto application. I have an old clamp on, and I really wish it worked on DC. Its a mid 1960s vintage Simpson that I got for a song.

What kind is your old meter? I have something of an affinity for old test gear, so its possible I may know how to make it go again. Old meters tend to be stupid simple and very reliable but it may have a blown fuse or something that needs fixing.

[GM_Guy]

Mfffff...

[L1011tristar17]

I guess that could have been a problem! I was sure that the meter measured DC amps, but then again I could have confused it with something else. It was just like this one: http://buy1.snapon.com/sep/catalog/i...6&sku=EEDM575D

As for the old one, I really wish I remember where I put it. I bought it at a school surplus sale, it used to be in one of the autoshop classes. It is actually in pretty good shape. I wish I remember which part of the garage it's in...

[GM_Guy]

Snap on sure lack specs on that meter, or an actual larger image so you can read whats on the meter. My guess is that meter is not intended for low current use, just high current starter draw, and overall alternator output to get you a good ballpark figure where exactness is not necessary.

You'll want to look at something that is a standard meter, with at least a 10amp DC capability. Stay away from a clamp on DC meter, you've demonstrated to yourself why they can be problematic, especially with low current circuits. I use a fluke 77 for just about everything.

Pay a visit to Walmart, Autozone, Radio Shack and see what they have available.

Alex.

[L1011tristar17]

Alright guys, I've had the car at the shop for about a week now. I just left it there and I've been driving a different car instead (Honda Odyssey, but it's decent.) The shop I took it to hooked up one of those ammeters and read a drain of only 14 milla-amps. How is this even possible? I remember the car being dead several times, and according to the meter there is no drain. They even left my car sitting for 3-4 days with the battery hooked up, and it fired right up without any problems. How could this be an intermittent problem? I think it's possible that there might be a short somewhere, grounding something out, but I'm not sure at all. Any insight? I'd hate to pick the car up and have the battery die again.

[L1011tristar17]

Could a bad defroster relay be the cause of the problem? Apparently the one on my car was determined by the mechanic to be faulty. Sometimes it's stuck open and sometimes it's not.

[Piece-it pete]

Iirc (it's been a while) this was a problem on my 87 MGM and it was the relay.

Pete

[miamibob]

Where is the relay on an 87 GM?

[Piece-it pete]

Iirc (and the grey matter isn't as accurate as it used to be) it was somewhere in the truck.

I looked at my 85 TC schematics and they mention the relay but do not show it on either the wiring diagram or illustrations

Pete

[tjc78]

My 89 LTC had a sticky fuel pump relay. That would certainly kill the battery pretty quickly. Just a thought, although I would assume you would hear that still running after you shut the car off.

I would get the car back, and see how it acts. If it still acts up, just buy one of those battery terminals with the shut off on top. A heck of a lot cheaper than paying a mechanic to try and track it down.

[L1011tristar17]

I finally bit the bullet and bought myself a multimeter to track down the problem. One thing I heard about some cars is that the computers take a while to go into "sleep-mode" after the car is turned off. Does anyone know how long it typically takes for the TC's computers to completely shut off?

[BerniniCaCO3]

I worked for volvo last year, and yes, sometimes computers (and there are a number of them in a modern car), take some time to go to sleep. We had issues with the radio receiver computer, the security/alarm computer, and the central module (which controls power to other auxiliary computers). Actually, logically, the alarm computer is always awake, just that sometimes it was more awake than its normal rest mode and killed the battery. That's neither here nor there for you.
15 minutes for everything in a volvo to go to sleep was normal.
Anything, like having a keyless entry key in proximity, or just trying a door handle, would then wake them up again (in preparation for you getting in the car and driving it).

However, your 89 TC is not that sophisticated. Pretty sure when the key's out the computer's off, and there's just one computer at that: engine control module.
The above is just fyi and probably has nothing to do with your draw.

It sounds like you're guessing around, and there's just too much in the whole electrical system of even these simpler cars to approach it that way: start by inserting your multimeter in line (in series, between a battery post and its disconnected terminal), car off, key out, and see what the current draw is.
If it really is 14mA, no, that will not kill your battery (any quicker than a couple weeks or a month w/o driving, anyway). 14mA is quite healthy. If your battery is going dead though, then there must be something there, at least some of the time. Test it multiple times. Maybe the shorting wire only sometimes rubs the wrong way, maybe the ecm computer only sometimes stays on, maybe the radio only sometimes keeps drawing power. I hate intermittent concerns, but it happens.
ALSO, if your battery really has .6V, or has ever had that few, it's toast. I may have overlooked it in an earlier post, but have you replaced the battery yet? Draw or no draw, a dead battery is maybe 10.5-11V. Once it's at even just 8V, it's been murdered and has some ruined cell(s) and will never have full voltage or capacity again. So maybe it's just a dead battery all along. A battery that has once been down to .6V, may never start a car again and may need jump starts all the time in an otherwise healthy car (good alternator, no parasitic draws).

[landmaster77]

My father had a battery draining problem years ago on an old Valiant. He found that the cigarette lighter was staying hot and draining the battery. He just unplugged the wire to it and kept on driving the car.

[gadget73]

Are you absolutely sure the battery is worth a damn? I've had marginal batteries that would fire the car every day, but it wouldn't if I let it sit 2-3 days. Also, be sure the alternator charges properly. I've seen and experienced battery failure because of a bad alternator. I've also seen alternator failure from a bad battery. Anymore I just replace the battery at the first sign of any trouble. I've been using those crap-ass Walmart batteries for a few years now, and it seems like every other year I'm in the store getting a free replacement. Since I started doing that, I haven't had any more trouble with the alternator.

[L1011tristar17]

After the battery first started draining, the alternator was replaced (bad bearings) and so was the battery. After that one was stolen I got an even newer one and it still drains. Last time I checked the alternator it seemed to be charging correctly.