HZJ81 - Batteries not charging when running. (1 Viewer)

[Yotajdmy]

I'm sure this is possibly an obvious solution, but I wanted to see if anyone had any insight here that I'm not realizing. Both (new) starter batteries read 12.6v with the truck off, truck running, both read 12.6 volt. Engine 2k+ RPM - batteries still reading 12.6v. 0 change in voltage. Wondering what the next logical step is in diagnosing the issue. Obvious thought points to a bad alternator, the truck has very low KMs, so I feel it may be unlikely, but certainly anything is possible and with age.. who knows. Any other ideas? Voltage regulator? Belt/ alt pulley? Should I just pull the alternator and test it? Any guidance appreciated.

Cheers!

 

[Dusten]

If you just installed new batteries go back over everything you have touched. Did you miss a wire?

If everything is connected then I'd test the alternator.

How long after starting are you testing? If the glowplugs are still cycling this will cause a big draw. Wait until you hear the glow plug relay kick off and check.


(Stolen from another post)

The alternator only charges when there is a voltage on the F terminal.
Check the Voltage Regulator. There must be ± 12Volt on the F (Field) terminal. This is the "signal" for the alternator to charge. If not then check for ±12V on the IGN terminal of the VR. This is the "sense" line from the Ignition key in "ON" position . If not, check fuse.
My guess is that you don't have 12V (in this case 9V) on the F terminal or 2nd guess: there is no 12V (in this case 9V) on the IGN terminal. No voltage here = no voltage from the alternator.

 

[Outsane]

You can get a shunt to know for sure..

I have the victron Bluetooth to monitor amps going into the system.

Do you have the stock alternator, it may not be keeping up.

 

[Yotajdmy]

Helpful info. I am testing right after starting the truck. Since you mentioned the glow plug relay....one more piece of information to add. When I am cold starting for the first time in a period of time, the glow plug light on the dash never turns off....no matter how long I wait. However, when I go in to start it a second time - even if it's just 30 seconds later, but as long as the truck was attempted to start very recently, the glow plug light cycles off very quickly. I find this to be slightly out of the ordinary, but correct me if I'm wrong.
It is the stock, original alternator, it's an 80amp. The cold weather spec factory alternator.

 

[Dusten]

Even in very cold weather mine doesn't stay in very long.

 

[Yotajdmy]

Problem solved. loose belt and alternator. stupid simple.

 

[Dusten]

Problem solved. loose belt and alternator. stupid simple.

I'm surprised it wasn't squealing.