Problem with Electrical Circuit

[Buzzy4]

I just returned from a week long fishing trip. At the RV Park where we stayed the first night while traveling, I noticed by my Tri-metric meter that the battery was drawing down even though I was connected to shore power. I glanced at the refrigerator and it was operating on gas. I checked with my circuit tester and the lights indicated Hot/Grd. Reverse (reverse polarity). I checked the shore power 20 amp at the site and it tested OK. I went back into the trailer to check there again and there was no power to the outlet at all. II assumed that the 30 amp was the problem and moved to a new site and all was well.
I left the next morning and stayed five nights in an RV park in Taos, NM with no problems. Circuit tester showed all OK.
I stopped at the same RV park in Amarillo on my return trip. When I plugged in my tester it again indicated Hot / Grd Reverse. Again the 20 amp at the site was OK. And again the power was intermittent when trying numerous times to discover the problem. I finally decided to move to another spot like the last time, thinking the problem was with the 30 amp wiring. I tried several sites and was not able to get the 30 amp to work. I finally gave up and decided to operate on batteries for the night.
We had power enough, but just barely. The batteries were depleted over 60% during the night. We did watch a movie on the TV that night and we also ran the furnace which, of course, didn’t run constantly. I know that these two are power hogs, but the draw down was much greater than any I had experienced.
The batteries were fully recharged by my truck while driving home. But, when I plugged into my shore power The refrigerator stayed on gas and the circuit tester again showed Hot / Grd. Reverse polarity. No charge is going to my batteries and it is slowly depleating.
Does anyone have any idea what the problem is? I have to work fast because I have a unit campout this weekend (boon-docking) and no way to keep my batteries charged.
Ed
The good news is, I had a great fishing trip.

[HowieE]

The first campground had a miss wired 30 amp plug. That is supported by the fact that things were OK when you moved to another site.

If this same condition exists at home I would first get a volt meter and check the wiring on your receptacle.

This does not sound like a problem that can be in the trailer, sometimes good and sometimes bad, but rather some miss wired receptacles.

As far as boon docking this week end I would charge the batteries with a battery charger for at least 24 hours, or plug the trailer into a good source for that period. Your truck will not charge the trailer batteries fully because the regulator in the alternate will shut down long before that happens.

[garry]

I will make an assumption here you say the CG 20 amp is OK!

So I assume you were using a 30 amp to 20 amp adapter?

I suspect you have a defective adapter.

Hot ground can be caused by an open neutral.

If you were not using an adapter you need to check your 30 amp plug for an intermittent open neutral.

[Buzzy4]

As it turned out the problem was only a disconnected wire in my power cord.
Thanks for the replies.

Ed

[richinny]

thanks for posting the resolution. :-)