Intermitent 'Low Voltage' indicator on dash readout

[alkillion]

Question for you diesel owners.
I have a 2014 Winnebago Forza on Freightliner chassis. It has an electronic readout on the dash. We happen to be in Colorado right now (meaning cold). When I started the coach the other day I got a 'low voltage' message on the dash display. The message would come on for maybe 10 seconds, then go off for maybe 10 seconds, then come back on again.
This went on for several minutes, then stopped. I could see the volt meter and when the message came on, the meter was down to about 9v. Normal is about 13v.
Was thinking maybe I had a bad battery, so I ask the folks at a repair shop. They said it was a "grid heater" that is used to warm the intake air until the engine gets up to temp. Batteries were ok.

The question is, does this jive with what you know?

Thanks for your knowledge.

[kedanie]

Now our rig is a 2010 and doesn't have a digital display, but I do pay attention to the gauges on start-up. Our volt gauge reads low for the first couple of minutes until everything heats up. Freaked me out at first, but now I have come to realize that it is a normal thing. Electric heaters draw a lot of amps and will make things look bad for a while, but it's really nothing to worry about.

Now if it does it after you are warmed up and running down the road, then that may be something to worry about.

Keith

[MountainAir05]

2014 should be in warranty, If mine would have it check out.

[Canadian_Rainbi]

There is a heater in the air intake to pre heat the combustion air. It does draw a lot of current that can cause voltage drop but 9 volts is way too low.

There are a couple of things that could cause this:

First is as you thought a bad battery, not able to supply enough current causing the voltage drop. However the starting motor draws a lot more, so if the rig starts that isn't the problem.

Another likely cause is a bad connection; loose or corroded, in the heater circuit. This appears as a high resistance causing a voltage drop.

Check every connection, starting at the battery. Don't just look. Make sure all are tight. If tight, remove, check for corrosion and replace.

NOTE Start with the battery negative terminal and leave it OFF while checking the others. This will avoid a catastrophic short while you are checking things on the hot side.

When you have checked the easiest to access, replace the battery negative and check for the error. If it is still there, continue looking.

[tmmar]

The explanation sounds about right. I have heard this explanation before. I too get the low voltage once in a while and the volt meter will fluctuate up and down for a minute or two and then everything settles down when sufficiently warmed up.