HMMWV Voltage High on Start

[EnteJager]

Truck starts no problem, voltage climbs into the red.
After about 40 seconds it drops immediately to the green.
Couldn't find anything in the TM. PMS Mag refers you to higher level maint.
Guessing its the voltage regulator??

 

[Coug]

Just for our info, what is the generator size? Is it a 60 amp, 100, 200, 400 amp?

 

[EnteJager]

Just for our info, what is the generator size? Is it a 60 amp, 100, 200, 400 amp?

60 amp

 

[NDT]

Southern Automotive has the parts and support you need. Don’t drive it like that.

 

[86humv]

You should use a multimeter to verify exactly what voltage you see before buying parts.
.

 

[EnteJager]

Southern Automotive has the parts and support you need. Don’t drive it like that.

I will thx.

 

[EnteJager]

I will thx.

You should use a multimeter to verify exactly what voltage you see before buying parts.
.

I will, thx.

 

[MarkM]

As others have said use a multimeter as the gauge should not be trusted when testing the charging system.

Mark

 

[Coug]

One possibility is your batteries are either too small of size or they are failing. Starting one of these trucks takes a lot of juice, so the battery gets drained down a lot. If the batteries get too low, you'll see voltage go up too high until they have enough of a charge for the regulator to bring it back down.

 

[EnteJager]

One possibility is your batteries are either too small of size or they are failing. Starting one of these trucks takes a lot of juice, so the battery gets drained down a lot. If the batteries get too low, you'll see voltage go up too high until they have enough of a charge for the regulator to bring it back down.

The batteries are .mil but 6-7 yrs old yrs old. Thinking that maybe the culprit. Cant get to the gen after start before it kicks down to get the voltage with a mutli meter. Gonna have to get a second hand. Thanks.