my truck is a 2005 cummins w/ fully built tranny, bd cp3, silver 66 turbo, bd 90hp injectors, fass system, gauges, edge juice with hot unlock, all mods done with in the last 2 years.

after my truck is warmed up (grid heater cycled and what knot) my battery level doesnt return to normal it goes 3/4 of the way up on my gauge, and stays there. any ideas? thanks

 

Brushes may be bad in the alternator...

 

i had the same problem. got a new alternator and new batteries took care of it!

 

How many volts is it putting out? Estimate?

 

Check voltage at both batteries.

 

Are you saying your volts are at 14.5 or close to 15? Mine is doing the almost the same thing. Mine just seems to be running high all the time at 14.5 and 15. I had my batteries tested at two different places and they said they were good, but I'm just unsure that they really are good. Shouldn't these trucks be running at 13.9 to 14.1 when batteries are good and everything is all warmed up?

 

No, charge voltage is dependent on ambient air temperature and battery temperature...pushing 15VDC this time of year is normal as the higher voltage is to drive a charge into cold/resistive batteries.

On edit: All my Cummins did this, and even this new Silverado does it.

 

Mine even in October was up around 14.5 to 15. This is with it just idling after the grid heater would stop and after driving to work for about 25 miles and letting it run for 5 minutes before shutting the truck down before going in. What should both batteries be at when the truck is off and just testing each at the terminals? Isn't it 11.9 to 12.1 or am I completely wrong?

 

Proper working charging system, right after shutting off from running a few minutes; the battery should be nearly 13.8VDC. It should drop to around 12.9VDC or so overnight?

Keep in mind, the higher voltage is to "drive" a charge into the battery...its normal to see 14VDC during the summer, and almost 15VDC in winter as the ECM adjusts the charge output on ambient temperatures.

And unless you're using a stand alone meter, the gauge in the dash is really an approximation.

 

I have the Edge CS Juice w/ATT and it has a PID for the BAT VOLT on it so I can see what it's running. Thank you for the info on winter or colder running volts.