Battery charging issue

[DeathStar2008]

When I first crank my LMM in the morning, the gauge registers at only about 11 amps charging. It isn't until I get down the road a piece before the gauge will jump to just above 14. It's been doing this for years, but has never left me stranded. I replaced the alternator a while back, believing that was the problem, but apparently it isn't. This morning it hesitated before cranking. Any ideas?

 

[LBZ]

It reads volts not amps and that’s normal. My ‘07 and my ‘16 both do the same.

 

[DeathStar2008]

Thanks. I can actually see the headlights brighten up when it jumps from 11 to 15. That's what lead me to think it's a problem.

 

[NC-smokinlmm]

It's the glow plugs and or grid heater turning off, totally normal. Might want to load test your batteries and clean up connections.

 

[DeathStar2008]

I check the connections regularly because of this. The batteries are about 5 years old, so it's probably time. Thanks.:thumb:

 

[THEFERMANATOR]

Normal glow plug and air intake heater operation. My lb7 stock would do it as well. I reduced the after glow time because it's primarily for emissions, and deleted the intake heater.

 

[jlawles2]

My LLY and LBZ did the same thing. Not quite that bad though. After changing batteries, it was better, but still not quite where it should have been. I ended up pulling both alternators and removing the back cap. On both the brushes were shot. total number of revolutions finally caught up with them so I had to change both. IIRC LLY was about 160k on the clock (4000+ hrs) and the LBZ was 180k on the clock.

 

[kiwilml]

My lml now does something that hasn't been normal on my other trucks.. I'll start it up after sitting over night or so and it'll idle up for a little bit, at 70 or 80 degrees outside even.. Got to noticing that the volt gauge was showing low and that must be why it was going in to high idle?

It always turns over fast and everything seems normal so hadn't been to worried about it but just curious why this one is doing that..

 

[Blackmax123]

My lml now does something that hasn't been normal on my other trucks.. I'll start it up after sitting over night or so and it'll idle up for a little bit, at 70 or 80 degrees outside even.. Got to noticing that the volt gauge was showing low and that must be why it was going in to high idle?

It always turns over fast and everything seems normal so hadn't been to worried about it but just curious why this one is doing that..

Not sure about the other duramax platforms, but the LML will activate high idle when it senses low voltage or a charging system fault. Just struggled through some charging issues with my lml after the built engine was installed. Ended up being the 2 pin plug on the back of my alternator losing contact. Mine would charge when the truck was first started but after driving a few miles it would quit charging till the truck was shut off and cooled down little.

 

[NC-smokinlmm]

My lml now does something that hasn't been normal on my other trucks.. I'll start it up after sitting over night or so and it'll idle up for a little bit, at 70 or 80 degrees outside even.. Got to noticing that the volt gauge was showing low and that must be why it was going in to high idle?

It always turns over fast and everything seems normal so hadn't been to worried about it but just curious why this one is doing that..

Load test passengers side battery.

 

[kiwilml]

Load test passengers side battery.

Ok I'll do that sometime, thanks..