So today I had to go to my parents house to do some work for them, had the truck loaded with the tools and materials I needed, noticed that I left my keys in the ignition. No big deal, I've done it before but, this time I left the ignition on some how. Started the truck, cranked just fine and fired right up. Volt meter was down a bit, comparable to as if the grids were on ( they're unhooked at the moment). Figured the batteries would charge on my 25 minute drive. I made it 1 mile and "check gauges" lit up, voltage now at 8. Checked the 150amp breaker, it was tripped. Reset the breaker, tripped again. Went back to the house and removed said breaker for now. Running late had to go.

 I don't know if I should reinstall the breaker now or not. Also, why would the alternator put out so many amps to trip it? Aren't the alternators (I assume mine is a stock unit) rated for 140amp output?

 Thanks for any thoughts. 

 Btw, the breaker I am referring to is one I installed after doing the WT ground mod.

Check your batteries.  One might have a bad cell and the alternator is working overtime trying to keep up.  I think @JAG1 had something like that happen to him.  

 That's a good point, the batteries are getting old. The date sticker is still on them. I don't remember the year off hand though. Plus I've been wanting to get a battery load tester anyway. Nothing fancy but with all the tractors and other machinery around here it would be useful.

11 hours ago, IBMobile said:

Check your batteries.  One might have a bad cell and the alternator is working overtime trying to keep up.  I think @JAG1 had something like that happen to him.  

Yep my alternator got so hot you could see the smoke coming off it. As soon as I changed the bad batteries I replaced the fried alternator and everything was O.K. Thing about this, is I had the batteries load tested only weeks before when they warned me about one battery having a bad cell, going dead. I didn't listen, so it cost me an alternator. I was lucky..... I could have lost the PCM too. Don't mess with old batteries on these trucks it isn't worth it. It could have cost me a tow truck as well. Thing is, you'll be driving along smelling the smoke, but you won't see it so you think it's from somewhere else, so you keep going not knowing your frying things up real good.

Edited May 24, 20204 yr by JAG1

 I looked at the batteries, they're dated 2014. 6 years old so it's probably about that time. 

 As for the PCM, I haven't done it yet but I want to put a dedicated fuse online for that as well. 

 Only bad thing about buying a used truck that's 19 years old. Alot if catching up to do on maintenance and preventative measures to avoid other serious problems.

Grid heater sticking on? Just fixed this for my landlord his truck would pop the 150A breaker.

 Mine are disconnected at the moment. Wouldn't be the grids at this point.

Ok thats my 5 cents I know. Might be diode issues?  Consider anything that might increase current draw through the breaker. Bad batteries, bad diodes, etc.

 That's the rout I'm taking. I'm gonna try to pick up a battery load tester in the next day or two and check the batteries.

 Now that the batteries are back up to, or should be up to full charge again I might try to hook up the breaker again to see if it still trips. It may have been a result of me leaving the key on overnight causing a severe draw to recharge once it was started. We shall see.

Edited May 25, 20204 yr by Doubletrouble