depends

Depends on options. A clock or radio with clock will draw power. So will an alarm system. Other options can draw power when the car is off as well. I generally use a test light instead of an ammeter.

 

No radio, no clock ..not much really as its a '49 PU with later mustang running gear though it does have onboard compressor for the air ride suspension. I don''t think it draws unless needed to maintain tank pressure though.

 

A .01 amp draw will not drain a battery in two days. You need to disconnect your pump and see what happens (besides truck taking a squat).

Trees

 

.01 isn't even into surface leakage. Did you check the batt water level? If ok or uncheckable, charge the batt at 10 amps for 20 minutes and do a load check on the batt. It should maintain 12v for 10 seconds.(average test time) If it doesn't your batt is about to take a squat.

 

Cells

Doc here, imp:

If you got a cell reading below 11 volts at anytime, you have a bad cell (s) Replace the battery..

Doc imp: