I mean converter, not inverter. I recently bought a '96 Coleman Bayport. Everything works on it, furnace, water heater, furnace, fridge, water pump, etc. I've been trying to learn all I can about it...and things were fine until Saturday. I brought it home last Sunday and set it up in the driveway to clean it. I plugged it into the house via the power cable. Everything worked fine. On Saturday the DW and I went out to start a good cleaning on the vinyl and such. We had unplugged the PUP from the house a few days earlier (after verifying things were working for a few days) When we plugged it into the house power the inverter started doing a high pitched tone. I found if I turned off the 1of the breakers it would stop...but that also meant that none of the plugs, the water pump worked. I think the other breaker is for the fridge...but i'm not sure. The inverter has 2 breakers (1 20amp 1 15amp) There are are 3 fuses (all are listed as 15amp) The inverter isn't stock, I don't believe due to what appears to be a patch in the cabinet next to it. I forgot to get a picture of it before I left for work..but can update with that after. I think the batteries are toast, because when we picked it up the lights were pretty dim on just DC power. They also have dates of 06/08 on the 2 12v batteries in boxes on the tongue. Is the beeping/squealing from a lack of charging on the batteries or is there something else that is possible? I'm finding it difficult to get much information on the Bayport since it appears to only have been produced in '96 and '97. I know most of the components are across multiple models and makes, but I'm still learning each one so I don't know what to cross reference.