House battery and generator

[tomdavisDOTcom]

My house battery has tested good. But now seems to not even charge when on shore power, with no juice to start the generator for it's weekly half hour run I give it. All other things work when plugged into shore power (but generator doesn't get enough juice to turn over even when plugged into shore power). If I start the motorhome, after about 10 minutes, the generator will start. I'm confused. Of course I thought the generator starter runs off the house battery, but if it does start off the main battery, why doesn't it start when the motor is NOT running. I'm perplexed

[Bama Rambler]

It would help if you told us the model and year of your RV, but since you posted in the Sunseeker section, I'll assume that that's what you have.

It sounds like your battery disconnect is open, or you have a blown fuse in the battery feed.

I don't know the intricacies of your sunseeker, but I assume that when the engine is running the alternator charges the house battery(s).

[Shredder]

did you try the override right at the generator?

try get a reading right at the starter for the Genny voltage wise.
Use a set of jumper cables. It has to be something simple.

[Grumpy7159]

I had batteries that measured 12.6 volts until I put a load on them. Checked them out with a load tester (Auto Zone will do this for you if you don't have a load tester) and the voltage dropped off considerably. A generator starter is a pretty huge amperage draw and if the batteries are not up to the challenge the starter will not turn over or will move too slow to start the generator. Good luck

[aircommuter]

I can clear up some things by telling you that shore power doesn’t supply starting power for the generator directly like it does for the 120 v a/c for the outlets. If the converter is working it will charge the batteries which will crank the generator. If the main engine causes it to start after running then it is doing so because it is charging those batteries.

[CHICKDOE]

sure sounds like what was posted in post #2. if you disconnect from shore power to any of the 12 volt devices (fans, lights) come on powered only by the battery? you say they do work when connected to shore power so i'm assuming the converter is powering them. check your battery disconnect or the main 12 vdc fuses / breakers in the battery feed from the converter.

the generator usually has its own dedicated feed from the batteries. this feed appears to be ok. you have low batteries as they are not starting the generator. you are charging them enough from the motor home alternator to start the generator. note that when you run the generator it needs 12 vdc dc power to operate and this is being supplied by the batteries. but since they are not getting recharged running the generator will actual run the batteries down.