[Jim-n-Kathy]

Hello all,
It's been a long time since Kathy and I have got on the site. The biggest reason is work, work and more work and not near enought play!
Anyway, today is a good day because we are [finally] all hitched up to Mr.Big Red Duramax and ready for a few days in the wild around Lake Lewiston in Northern, CA [we live in Folsom, CA].
So as usual I have a Monty question. I have the electrical service plugged into the house AC at this time and do not have any appliances on in the RV at this time. However I detected a humming noise and traced it to the power invertor fan in the basement near the demand pump. My question is; I do not recall hearing this running noise in the past. Is this a normal thing or is it just working because my dc batteries may be a bit low from storage?
Thanks for your help.
Jim and Kathy and Sami the lab