Battery troubles

[MKD]

Finally got the truck running good enough to get it registered yesterday. This truck has power like a mule. I'm having an ongoing problem with the charging system though. The batteries where draining while off. I found the problem was that it grounding through the voltage regulator. I swapped it out with a uesd one I had and it fixed the problem. While driving around yesterday I noticed that the batteries where not charging much if at all. I let it sit for a couple of hours went to go do some running around and it was dead again. Any ideas as to what might be causing troubles would be greatly appreciated.

This is going to be my logging truck. I have a big crane and some old mining track that I'm going to weld up to make a big rack on top to stabilize everything. That is if i can get charging right. I'll post pics after paint etc.

 

[icanfixall]

Welcome to the forum. My guess is the alternater is not opening the circut it has in it when you shut down the engine. If said circut stays closed or in the on position the batteries will drain backwards into the alternater. To test this remove the large wire off the alternter that runs bck to the fender solenoid. Be careful when working with this high amp circut. You have both batteries amps ready to ground if you touch anything. Thats around 1800 amps of wrench burning amps...

 

[alienturtle]

icanfixall is right. it sounds like its draining back. if you have already replaced the VR with a known good unit and its still draining back then the only place for it to do that would be the alternator. From what i understand there are a series of diodes (one way valves) built into the alternator. If one or more of these guys burn open it is no longer a one way valve and you are basically charging the alternator coil thus draining the batteries over a period of time.