Parasitic draw? Pete 589

Your fuse rack in a truck is almost the same as a car. Find the one hot and one cold and start pulling fuses until you detect the draw.

Never mind the four batteries. If you need to put a meter on each of the four.

My hood light underneath was the last parasite I found so far. That took a little hunting until one day I noticed it was glowing. hmmm.

 

Next time you park it for a period of time disconnect the batteries from each other. One battery with a problem can kill them all.

 

If you have installed a master kill switch to prevent drain, you still have something hard wired direct to the batteries causing your drain.

It is measured no different than a car. Just the amount of drain can be higher over a given time, as you have more reserve capacity with 4 times the battery storage or more.

Is your alternator powered through your master switch? Shoot it with a temp gun to see if its still warm after setting overnight, or disconnect and see if your drain goes away.

 

I'll go one (or two) better and say take the box cover off and look for any bulging batteries. Then disconnect them all and test each one individually. A battery that won't charge will draw down the others.
Since you have an APU, do you still have 4 batteries?

 

If your master switches were wired up properly, there will never be a parasitic draw on the batteries with the switch open.

This should be real easy to T/S. If there is something hardwired to the batteries, master switch open and batteries die, its either a faulty battery or the object you have hardwired that's causing the draw.

 

Was down in FL one time, just got done unloading, went to fire her up, clicking, WTF, was working perfectly fine up to now.

3 battery system, disconnected all the cables, took a test light (had no voltmeter with me) and hit each battery. After doing this a few times, I saw one that was a little dimmer, not by much, by watching the test light.

One battery had threw a cell. I walked a ways, bought another battery, walked back and hooked them all back up, end of problem....

 

The first time I saw this was in a K100. It ran fine everyday. However after it sat for two days it would not start. Jumped it off and it would run for the week. Next two days off it would not start. Charged all the batteries. Knocked the surface charge off and load tested. They all passed. Truck ran all week and we disconnected all the batteries. On the third day one was dead. Replaced it and no more problems.

 

@Final Drive

 

Got-it !
Thanks