I had the problem of a "bad battery" on my '74 van. I put an ammeter on the 
battery and found a 50 milliamp drain which was enough to flatten the battery in
a week of no driving.

After checking, I discovered that the cheapie radio I put in was keeping the 
LED's on all the time and that was the problem.

An in-line switch for the radio was all that it took to fix the problem. I 
feared that the radio would loose its settings and time but it doesn't. Can't 
figure that out.

BTW, ammeters can be had for about $10 in the cheap versions and are no-brainers
to hook up. They will be a sure way to find the current drain.

Question?? Why is it ammeter not ampmeter?

Herb