Question: You know for a fact that the alternator is working, is that correct?

 

I think you are right about <75 MA being in tolerance from what I remember.

Just a shot in the dark...... the 250 I had before this one had a flaky switch in the glove box and sometimes the light would stay on with the door closed. Almost never found it and it would just do it sometimes. I guess you will have to keep searching. These things can be tough and I'm thinking it takes something pretty "find-able" to draw down 2 good batteries in that amount of time. That is if you can catch it in the act.

I think I'd leave my meter hooked up and just check it now and then if it's sitting. Must be an intermiddent thing or flakey ground connections somewhere that come and go.

 

Let's assume the alternator is working fine (my first thought is the alternator is not putting out rated amperage...perhaps it reads 14.1 volts but only a few amps - battery goes dead slowly). Your comment got me thinking about weird possibilities. How about one of the relays to a large battery draw accessory powered via a relay is flakey and stays hot after the key is turned off. I don't know if it is possible, but might be . When the relay is open the OP gets a low mA draw...but when it goes flakey the draw is high and kills the battery.

 

Something like a sticky IDM relay?

Pop

 

I almost forgot for doing long wire sections and areas you can not feel every wire I have a telephone receiver and a battery pack that puts out a tone it has small alligator clips and is great for finding broken wires.

 

As for the alt, I have to assume it's good... Prior to this alt the system displayed similar behavior. Alt amps...? If the truck sits for 3-4 days I can hear the weakness while starting, not seriously weak, but noticable. If I drive 10 minutes and restart it, it spins like a champ... Seems to charge fine. Volts are steady at 14.1. Looks like I'm going to be carrying my meter in the truck and spot checking whenever I can.

FWIW it seams to be worse when cold, but I'm only talking mid 30's not really cold...

 

I would not assume the alternator to be good...BEFORE delving into this problem too deeply, eliminate the easy things first. I'd drive to an auto electric shop and have them test the alternator for output (amperage specifically).

 

Make sure they also look at AC "ripple", as that can help determine if any diodes are bad.

Pop

 

Probably nothing to do with your problem but....... read on another thread about a member that had batteries dieing and it turned out to be one of the lights on the visor staying on even though the lid was closed. Just thinking of anything it could possibly be !!

 

Doesn't it seem that it would take days for the glove box light or the engine compartment lamp to kill our batteries, and not just over night?
I'm currently poking at a similar problem...

 

It would indeed for the glove box bulb only 2.66 watt draw...the underhood draws almost an amp though (that is the reason I just leave it slightly pulled out so it only works when I push it in all the way).

 

He said they would go dead after 7-10 days. I agree, glove box or small bulb draw shouldn't kill them over night. Under hood light draws a good bit more amperage, I didn't know how much more till Neal posted.

These things can drive you nuts. It takes time and patience to find and fix them. Don't give up !!

 

I was having the same problem. I finally found out that my glove box light bulb was staying on and kept killing my batteries. Pulled the bulb, problem solved.

 

I'm going to pull the glove box and hood light just for kicks. Once I get my kid out of the fridge, I'll see if I can cram him in the glove box to keep an eye on that one too...

 

Mine did the same on my 96 with the glove comparment. It had weak battery though and killed it after sitting 2 days. Stumbled on it one night looking for something on the floor in the dark.