"alt charger" dash light

[bkphotog]

HI Guys

First lets me tell all of you that I am a total novice when it comes to electrical and automotive (MH) issues.

Here is a new behavior that my MH has just displayed for me to my dismay. I am at a loss.

Went out today to start up the engine to check on the air levels. The MH has been unplugged from shore power for a couple of days with the cutoff-switches in the battery compartment in the OFF position. I first connected to shore power. Started the engine and it kick in right away. Air was slightly low so I kept it running to build up the air. I did this so that I knew I was at full chassis height to let the slides out. Then it happened.

The "ALT CHARGER" Light and alarm in the dash came on for a couple of seconds and then went off. It then came on again for a few seconds and then went off. It did this behavior several times for the next several minutes. Each time staying on just a bit longer but it would stop also.
Now I have never observed this behavior for as long as I have owned this MH. I am at a loss.

This is a 07 HR Neptune with the original batteries (house / chassis). It also recently had battery maintenance done in cleaning up the terminals and checking the fluid levels in the cells. I have been doing this filling and checking of the distilled water levels monthly since day one. but I had a MH tech check all this recently because I had some other yearly maintenance performed. They stated that the battery condition was fine even though the house batteries were just a bit low when I picked up the unit.

At this point I need guidance from all you electrical / automotive guys /gals on what I should be looking at in trying to solve this behavior. Is it my batteries (condition)(age) or my alternator or what ever? Could the tech connected something to the wrong terminal when he cleaned up the terminals??

Any help and thoughts would be welcomed.
Bill

[grumpy14]

Maybe brushsin alt,have alt shop ceckit out also maybe inter voltage regulator.

[zman62]

Did it just come on at idle???

[bkphotog]

Yes it came on just as the engine was idling as the air was building up in the tanks. I have not checked it in the last couple of hours with the MH connected to shore power. The charger / inverter seems to be holding the house batteries at around 13.4 with a "float state" achived, and the engine off. When it happened initially the house batteries were in a "absorb state" and was charging at around 14.4 to 14.7 or so. Not sure what all this means.
Bill

[H. Miller]

It's been awhile but we were having the same problem until the light stayed on! Only an hour from home so we continued.
Removed rearmost bedroom "floor hatch" and started checking wires around alt.. Two smaller (16-18Ga) coming from the alt. went into a black plastic box about the size of a cigarette pack (except 3/8" thick). Inside were two 5 amp fuses. One was blown - replaced and no problem since.
They are not shown on my wiring diagram but I think they are "field" wires/fuses and with only one working, the alt. is at half output therefore the light especially with low batteries.
The "box" was 12-14" from the alt.