Battery drainage.... help!

[Fel]

Okay, so I'm having this awesome problem with my battery....

If I leave the car off for more than a day, the battery dies. It's not the battery, I've already replaced it with no results. I've also checked a few times that I'm not leaving any lights on or anything.

Kind of sucks going somewhere and fearing that your car might not start by the time you get back to it.... I've taken to disconnecting the positive lead on the battery every time I'm out and parked jsut so it doesn't drain.

So my question is..... where do I start?? What could possibly be causing it? (Out of the 10 billion posibilities....) Could someone give me a checklist of sorts of what I should look at as a possible drain?... maybe starting from cheapest to most expensive...

Thanks...

[Liam]

Pre 89: Glove box or (all years) trunk lights staying on?

Do you have a volt meter?

Know how to test for a draw?

[SpecM]

do you have a multi-meter? Put it inline with the pos. batt cable, and measure the amperage flow. Pull the fuses one by one until the flow stops (or drops below 0.5 amp)

that will narrow down the circuit that is drawing the current

[wodcutr]

You need to get a bentley and go through their checklist for battery drain. You have to hook up a meter in line with your battery cables and pull each fuse one at a time to find the circuit that is causing the fault. It that doesn't yeild anything then it is most likely the starter or alternator that has the problem. Also might want to check your trunk to see if it is closing all the way, enough to turn the light off!

[jlevie]

Diagnosis of this requires measuring the current drawn from the battery when the car is off and doors/trunk/hood are closed. That is best done by replacing the battery ground connection with an autoranging digital multimeter of at least 10A capacity. Normal parasitic draw is 30-60ma. If the car has excessive parasitic draw you pull one fuse at a time until the offending circuit is found and then troubleshoot that circuit to find the offending component. A frequent cause of excessive parasitic draw is improperly installed aftermarket electronics, like audio gear or alarms.

If the car isn't suffering from excessive parasitic draw the problem will be caused by a bad battery (not likely in this case) or the alternator. A quick check of the alternator's condition is to check system voltage at idle and 2500rpm. At idle you should see 13v or better and at 2500rpm you should see about 14v if the battery is fully charged when you perform this test. The system voltage should not be greatly affected when you turn on the headlights and HVAC blower if the alternator is working properly.

[SpecM]

+1 to ^

also, check AC voltage (as opposed to DC) with the engine running. It should be less than 10 mV, anything over that indicates a bad voltage reg

[Fel]

Sweet, thanks for the info guys. I'll try to track down a meter and give the fuse thing a try!