Electrical Charge

[JohnnyR]

My 2012 K3500 HD dually/ Duramax LML takes about 3 to 4 minutes to finally reach a 14 volt reading on the ammeter gauge after I start it. On my previous 3 Duramax trucks (2001, 2003, 2005), attaining 14V was within seconds whereas this one stays at 12.5V and slowly increases over the 4 minutes or so. Anyone know if this normal for this model?

[dually2002]

MyLB7 did the same on start-up as your LML. Even in hot weather it would do this. In my case I think the glow plugs were still cycling and the manifold air intake heater was operating. Mine would stay on 12.5 volts any where from 30-90 seconds depending on the outside temperature. Ever since my SES light came on for a glow plug fault the charging voltage goes immediately to 14.5 volts. The LML has more emission related components that might be the reason for the charging rate.

[EdSpaek]

MY 2013 LML takes considerably longer to reach 14 volts on the voltmeter after a cold start than my 2008 LMM did. I believe there is now another heater circuit in the DEF tank that I attribute the additional heavy drain to along with emmissions control and glow plugs. I also notice when it is in the 40 degree F range the battery appears to overcharge a bit, the old truck did something similar but not as high as a charge

[JohnnyR]

I have concluded as well that the extra emissions stuff is the cause. I read somewhere there were initial problems w/DEF freezing. So an extra heater there would make a difference. I have also experienced a higher charge in certain conditions as well. Thx for the input.

[More Power]

These alternators are somewhat more efficient when cool/cold. It's normal for voltage to be a little higher when the alt is cool. If you think it's tool high, first measure the battery voltage with the engine running with a digital multimeter to be sure.

Jim

[Dinkie Diesel]

I've had several duramax trucks. I currently own a 2014 LML and before that it was a 2001. I went through batteries like underwear on the 2001. New batteries every 3 or 4 years. Used to think it was the nature of the beast. After paying more attention to the voltmeter I saw voltages above where I think they should be. The gauge was hard to interpret but my multi-meter showed 14.5. I used to believe the charging voltage needed to be between 13.8 and 14.2. Put a new alternator on the 2001 and it was the same 14.5. I think that is too high. I'll bet it's boiling the batteries.

Sold that truck and bought a 2014. I'm at the 4 year old mark now and it wouldn't start for me today. Tried to jump it with a portable jumper, no luck. Tried a 50 amp buzz box to charge it for a while. No luck. Took the battery cables off and cleaned all 4 of them. Voltmeter says batteries were at 12.1 volts. It's been sitting a while. Didn't think that was out of the ordinary. After twisting the key multiple times it finally cranked and started. Drove it around for a couple of hours and checked the voltage at the battery while running. Alternator was putting out 14.8 volts.

It's way too much of a coincidence to own two trucks that do the same thing. Why in the heck do these truck push so much voltage? That can't be normal. I have the same delayed ramp up in voltage as described on these pages on both trucks. After starting the engine it is 30 seconds or more before it rises above static battery voltage. On another forum one guy said the passenger side battery is subject to run off water and it ruins the battery over time. That sounds plausible. I don't have any corrosion on my terminals at least none visible. Wondering if the slight DEF spillage has corroded something somewhere? I wash it off with a hose immediately but who knows where that corrosive stuff landed.

I'm not going to just run out and buy batteries every 3 or 4 years only to find out I have a underlying problem. Any ideas?

[More Power]

After starting the engine it is 30 seconds or more before it rises above static battery voltage. On another forum one guy said the passenger side battery is subject to run off water and it ruins the battery over time. That sounds plausible....clip

I'm not going to just run out and buy batteries every 3 or 4 years only to find out I have a underlying problem. Any ideas?

When starting the Duramax, the intake air heater remains energized for some time, depending on engine temperature. The heating element pulls more amps than your alternator can supply, so battery voltage will rise once the intake air heater shuts off.

Like you, I believe that the passenger side battery resides in a hotter location under the hood. This cooks off water sooner than that experienced by the driver side battery. It's important to transfer the insulation sleeves used on new batteries in new trucks to any replacement batteries.

The ACDelco maintenance-free non-serviceable batteries that came with my 2001 GMC from the factory lasted for nearly a dozen years. And, they never leaked a drop... I replaced the OE batteries with ACDelco batteries that came with removable caps and a need to top-off occasionally. Never again.... They are leakers, and the passenger side batt leaked (vented) enough to corrode the battery tray and related areas. Never again will I buy vented/serviceable batteries.