I've seen that happen. Kept a vehicle for about 4 days and routinely checked the draw with a clamp meter and checked the battery with a digital battery tester. Everything seemed good and I figured the customer must be leaving something on. I went to check it for the last time and it showed a 3.6 amp draw which ended up coming from the A/C compressor clutch relay. With the key sitting in the seat you could plug it back in and you'll hear the relay click and the compressor clutch click.

20ma parasitic is no issue for the battery as you know. Are you measuring the drain correctly?? Are you reading the scale correctly on the meter??

Does the parasitic drain change over night?? Is someone turning on a light in the car just to piss you off??

It could be a faulty diode in the alternator. It would still charge while running but immediately start discharging the battery when the car is turned off. It's a pain to do but you could start pulling fuses while observing the meter til you find the circuit that causing the drain.

guys, shouldn't there be a drain in order to discharge my battery? Is there any other way ? Because the measured drain is 20mA, which should be fine. Can you tell me how to check contacts from and to alternator step by step?

Do the fuse check, and check for the obvious: faulty connections like bad insulation, rusty ground connections, loose connections, etc

Please help. I own a 1997 ford escort europe MK something, and I have this strange problem :

Whenever I leave battery connected overnight, it ends up empty . The thing is, if I disconnect it and connect it before use, it works and never discharges. The alternator gives it proper juice, everything is perfect.

Now, the fun part. WHen I measure parasitic drain, it doesn t exceed 20mA.

Is it possible some relay switches on at night and takes huge load from the battery? Or where would you look for a problem. The battery itself seems very fit.