I seem to be down to this as the source of my parasitic drain. How does one diagnose this? Can I pull the alternator relay and see if the amp draw drops, or is it deeper than that? And then, is this new alternator time or can I just have the diodes replaced? I'm a gearhead, can wire your house or your pre computer car, but I'm not much on electronics.

 

Anyway you can disconnect the alternator from the rest of the car should do the trick as long as you're not trying to drive it.

 

From Rockauto website

1. If in step 2 the voltage across the battery terminals was 13 to 14 volts with the engine running, then the alternator is properly charging the battery. That is good news, but there is another alternator electrical problem to check for. I know from personal experience with a Ford 5.0L. that sometimes an alternator can charge fine when the engine is running but drain the battery when the engine is off. It probably has something to do with the rectifier diodes in the alternator not properly blocking current from draining away from the battery. This problem may be intermittent. It certainly was on my Ford 5.0. Disconnect all the electrical connections from the alternator when the car is put away for the night. If the battery never goes dead with the alternator disconnected but goes dead when the alternator is hooked up, then that might point to an alternator diode problem. RockAuto sells replacement diodes for some alternators. The diodes are buried so deep inside many modern alternators that replacing the entire alternator is often the most practical option.

 

noticed on my disco,03 with the French alternator,alternator field is turned on in certain situations with key out of the ignitionnce,with belt off,turned the alternator and it "cogged"as field was powered up-this was shortly after I had opened the door and courtesy lights were on,a bit later,lights were off and alty field was off and it spun freely...Odd,but possibly normal ? No abnormal batter drain noticed.

 

I leave my key in the disco frequently when parked in my garage....any chance that is keeping something energized?

 

Not so quick. Drove to work after being on charger last night. When I got ready to leave work at 5, it was dead. Jump box got me going. When I got home I checked it out pretty thoroughly as follows.

Charging 14.2

Shut it off, battery holds 12.8 Battery is a known to be good one.

Started the milliamps test with my Fluke set on 30mA scale and connected between unhooked battery ground and battery ground post

About 46.2 mA consistent draw. Barely enough to flicker a 12 volt tester

Pulled every relay and fuse in the engine compartment panel one at a time with no more than 1 or 2 mA total change

Unhooked lead to alternator. No change

Wife got home. Asked her to watch the Fluke while I pulled the fuses on the drivers side interior panel

Opened the door and it went to 400+ mA

Thought I'd hold the door switch while I pulled fuses. Silly me, it doesn't have a typical door switch, and I couldn't find it....

Closed the door. Draw stayed up around 290mA. Cycled the key and closed the door. Dropped back to 46.2mA

Opened the doors and made sure every dome light was in manual off position. Unplugged ultragauge. Cycled the key. Closed doors and it stayed at 290.

On a whim, I hooked battery ground back to battery and pulled it back off and checked draw. 27mA

Opened door and cycled key. Back to 290. Went to feed cows, gone 30 minutes or better. Still 290. Everything was off, key out of ignition, dome lights off, doors slammed. Never got it back to 27, which I suspect is approaching acceptable. I noted that cycling hood switch by hand jumps it up.

Put it on a 2 amp charge and came in for dinner. Gonna get the rave open on my tablet. (electrical section)

I'm thinking at this point its the door switches or security system. Looking for some help / guidance / been there done that, please...