weird electrics lag

[neuroboy]

For my inaugural post, I have a car whisperer-type question. I have an '89 325iC (about 150k miles) that's having a really strange electrical problem. When I first start it after it's been sitting for a couple days it seems as though the whole electrical system (for about 15 minutes or so) is running on like 10% power. The wipers barely have the strength to make it down and back on the windshield, the windows almost can't roll down, the a/c fan doesn't really blow, the turn signal lights on the dash don't light up, and the engine runs really rough as though the spark plugs aren't firing right and it has kind of a "stall-y" feel about it even though it doesn't actually stall.

After about fifteen minutes in everything sorts itself out and begins running normally, but for that first fifteen minutes it feels as though the car is just about to throw it's hands up in the air and say "ok man, I give up". It just started doing this after I got it back from the shop--I brought it to them because the a/c fan wasn't working at all (they said it just has a bad relay).

any ideas?

[phenobarb1]

Your battery is shot.

[jlevie]

This could be a case of a dying battery (or excessive parasitic draw) compounded by a weak alternator.

[neuroboy]

Yeah, that sounds about right. As it is, I have something drawing from it slowly. . . if I leave it for more than a day or so (as I often do) the car won't start without a jump. I usually disconnect the battery every time I park the car if I know I'm not immediately coming back.

Any thoughts on what might be draining the batt are welcome, too.

Cheers.

[phenobarb1]

While you could have something drawing power from the battery when it is just sitting, which could be practically anything electrical in the car, there is a decent chance this isn't the problem.

If your battery is fairly old, or maybe just damaged somehow, it might not be able to hold a proper charge. It sounds like it holds just enough of a charge to fire up the engine, after which your alternator seems to be doing its job of providing sufficient juice for the cars electrical demands.

So, assuming that nothing has changed recently with the car, like adding a new car stereo or monkeying with other electrical components in the past month, and that the car was probably running and starting properly until sometime in the past month or so, I would test the battery. Some sort of parasitic drain is possible, but generally if things have been left alone and not tampered with is somewhat less likely (though possible).

Hopefully it is just your battery dying as the alternatives will probably be either more annoying(searching for a drain), or potentially more expensive(alternator, which I doubt is a problem, but you might as well test this anyway while you are in there).

[neuroboy]

So, assuming that nothing has changed recently with the car, like adding a new car stereo or monkeying with other electrical components in the past month

See, that's the rub. I recently had it in the shop for a dead a/c fan. It turns out it was just a blown relay, but I don't know how much futzing was done before they realized it.

The dead batt if left connected was an issue before the recent shop internment, but the low juice wasn't. The trip computer screen was d.o.a. when I got it back, too, so I may be dropping them a line anyway. Man, I wish I had a garage to do my own work in. Not knowing what they did makes it tough to figure out what's going on. Sadly, doing bigger projects from curbside it's something I really want to do especially given this is my first go around with a relatively older car.