Home Forums Gear Hunting Trucks and Four-Wheel Drives Question on the voltage regulation and charging for the 5.9 cummins

I have experienced the craziness of what happens when a battery dies in a newer vehicle several times over the last couple of months. Whan I run my Smittybilt 10K winch on my Jeep, it will draw close to what the alternator is putting out, and fool the voltmeter into thinking the battery is dead. When I run the winch, the voltmeter will go to zero, but the battery is fine. I am running an Optima Red Top and it is considerably stronger in CCA's as well as reserve minutes than the stock battery that the Jeep came with. I have to shut the Jeep off and restart it to reset the voltmeter after I use the winch. It has never failed to start.
My wife has a 2010 4WD Suburban and its freaked out last week when the battery took a dump. It was putting out 13.6 volts, but only about 90 amps when we tested it. $129 later, it works fine...

In sub zero weather We have started bringing a Honda Generator with us. One guy with a Duramax and old batteries used one guys each morning last January at -13. It will keep popping the 12v breaker until it gets a little charge in it. I assume a person could pull the ground off one battery, If the generator was not able to take the load of 2 dead batteries. My 07 cummins is still on the original batteries About 5.5 years. I have been worried about them.

Had a charging issue with my 06 cummins this week. Cranked over slow when I was leaving work, but started. The volt meter in the truck was reading low, and did not bounce back. About half way home the check engine light came on, so I checked codes when I got home. Had a "low voltage" and another code that there was no voltage drop registered when the grid heater came on.

So, got out the multimeter, checked both batteries, and both read low. Started it up and checked both batteries, and they were both still under 12 volts. Wanted to check alternator voltage so I crammed the probe in where the alternator terminal connects. Apparently I completed a circuit, because I read 36 volts, and massive sparks flew out. In fact enough heat was generated that it melted the OEM terminal.

So, I went to the interwebs, and did some research. I knew I had a bad positive terminal on the passenger side, it was cracked and needed replacement even before I melted it. My theory is that the ring terminal going from the alternator to the passenger side positive post had enough corrosion that it didn't allow conductivity to either battery. The ECM reads no charge coming from the alt, so cranks up voltage. In my case the lack of conductivity to the positive post saved my battery. If there had been a bad connection from the crossover positive cable to the drivers side, or a bad ground on the drivers side, it would have cooked my passenger side battery. If the connection to the positive post on the passenger side was bad but current was still getting to the drivers side, I would have just had a weak passenger side battery and crappy starting until I destroyed the drivers side battery.

I went to our local electrical house the next day (polar wire) and got some of these: Mil-Spec Battery Terminals, some 2/0 solder-on ring terminals, and heavy duty heat shrink. Cut the terminal off the crossover cable, soldered a ring terminal on, cleaned everything up, hooked it up. Did some half-way scientific resistance checks on all other posts to make sure I didn't have any horrible grounding issues. Then sprayed some sealer on the new terminal/connections.

All is well for now, and the fix was relatively simple/quick. Will do the other terminals and clean all my grounds when the temps are above zero. Working on cars at 10 below is just not that much fun, and 2/0 wire doesn't really enjoy being routed properly either.

Here is the terminal I replaced.

Looks like some jabroni took a hammer to the terminal. Got any suspects?

What's that saying?.... "If you can't fix it with a hammer, it must be an electrical problem"

Not 100% accurate - you can both solve and create electrical problems with a hammer!

All my terminals pretty much look like crap - jumper cables working in both directions and pulling batteries to start other rigs doesn't really help, but they are sort of a BS design.

No worries. The terminals on my taco looked like that - until I replaced them in Aug because they could not be tightened enough to be effective. The new ones are nice...for now.