About 3 weeks ago my brother bought a 2001 2500 Suburban. At the end of the first week it would drain the battery nightly to the point that it wouldnt start. I let him take the battery out of my 66 Impala project car so he could order an Optima for it, my battery is an Exide and is only a month old. Now, about two weeks later it started doing the same thing. If it sits overnight it wont start.

Has anyone had a similar problem? Is it the alternator, regulator or something else?

The truck is 100% stock.

Thanks,
Eric

 

Start looking at the obvious stuff...

Is an interior light on?
Something in the cigarette lighter?
Under hood light on?

If that stuff is normal, get an amperage meter (Fluke makes one) and see what the amperage draw is. If it is dead overnight, it is pulling a hard-core drain. I'd guess the voltage regualtor first off unless there is some aftermarket electronics installed.

Just unplug that regulator from the alternator and see overnight if you don't have an amperage draw tool. I have fixed three charging problems in the past: '72 Cadillac Fleetwood, '78 Buick Turbo (yes factory carb turbo!), and my '88 F-150

Hope that gives you an idea where to start,
Eric

 

As said you put the multi meter in Amps and put meter in series - battery post and - battery terminal. I think 32mA draw is max allowable if over that pull fuses and find the circuit that is drawing the amps.