Intermittent Battery Discharging

[cosmophone]

Occasionally the battery on my 1995 Explorer will be discharged after sitting overnight (less than 24 hours). I have tested the alternator and it's good. I have tested the battery and it's good. I have tested the quiescent battery current drain and it's about 20 mA after the Generic Electronic Module has timed out. This happens after the ignition has been turned off and the doors have been closed for 45-60 minutes. Before that time out period the current drain is about 300 mA.

I replaced the Generic Electronic Module about six months ago because the original one had a problem (it wouldn't shut off the Battery Save Relay after the 45 time out period). Prior to replacing that module the battery would drain down in 2-3 days. I don't think, based on my recent measurements, that the GEM is bad again. Like I said, this is intermittent. Some days it happens, some it doesn't.

All electronic functions on the car seem to be working properly. I will continue to monitor the battery voltage when the car is sitting and hope I can find something but I thought I would put this problem out there in case any of you have experienced the same thing.

Thanks, Brian

 

[jremington59]

Is fuse 25 for your GEM? If it is, pull that fuse and take a reading.

 

[budwich]

"quiescent battery current drain"... I like that ...

good testing, the lower figure for drain is good BUT the higher one (when not in "quiescences"... ) might be a problem... not overly high in normal operation BUT in two to three days, that represents about <30 aH which is high and probably not good if it remains there. I personally don't believe that GEM's go bad as fast as people make out on the forum... more of an "underlying" contact or wiring issue that gets "solved temporarily" by replacing the GEM. Since you are familiar with the operations of the relays that are involved, I would check wiring at them / near them for issues. The GEM basically "switches" in grounds to control them... either applying to activate or removing to drop. If they aren't dropping, could be a sticking relay OR a false ground (shorted wire) somewhere along the run from the relay to the GEM.

 

[CobraSix]

I'd start checking for grounds. More than likely it's a loose wire somewhere making (like bud said) a 'false' ground.

Could be a relay somewhere staying open (or closed depending on normal operation).

 

[Marvial]

I have approximately the same situation. My battery has gone dead four times, but recovered with a good charge. It does not happen often, but seems to me like something not shutting off sometimes. If I disconnect battery and then reconnect with a A-meter in series, I can see about 3 amps for 10 seconds, and a "whirr" sound in the engine room. After 10 seconds the current goes down to 0.24 A, which seems to agree with the statement in this thread, a bit much. Any ideas how to proceed?? Also second question, there is a switch that closes when hood is closed. But, there is no light I can find under the hood, so what is this switch for?

A little tip, if you want to measure current in/out of battery without disconnecting the battery, I found that the black wire from battery to chassis has approximately 0.001 ohm, i.e. measuring 4.88 A out of the battery, I get about 0.005 V drop over this wire. So, use a good DVM, set for milliVolt range, and it will show you drain current in amps. Coincidense?

:exp:

 

[Marvial]

Which relay is that?

Occasionally the battery on my 1995 Explorer will be discharged after sitting overnight (less than 24 hours). I have tested the alternator and it's good. I have tested the battery and it's good. I have tested the quiescent battery current drain and it's about 20 mA after the Generic Electronic Module has timed out. This happens after the ignition has been turned off and the doors have been closed for 45-60 minutes. Before that time out period the current drain is about 300 mA.

I replaced the Generic Electronic Module about six months ago because the original one had a problem (it wouldn't shut off the Battery Save Relay after the 45 time out period). Prior to replacing that module the battery would drain down in 2-3 days. I don't think, based on my recent measurements, that the GEM is bad again. Like I said, this is intermittent. Some days it happens, some it doesn't.

All electronic functions on the car seem to be working properly. I will continue to monitor the battery voltage when the car is sitting and hope I can find something but I thought I would put this problem out there in case any of you have experienced the same thing.

Thanks, Brian

What is the "battery save relay", I assume it is named something else?
Regards,

Marvial
:exp: