Tripping gfi in garage when plugging into garage

Update have riled out hot water heater element. Took to Tv place and it was ok. I am now thinking that the charger is tripping gfi due to amps required on startup. Disconnected battery and was able to connect with no tripping. Will be taking battery to auto store tomorrow to have them check battery. Rv is only a year old but not sure why battery won't hold charge. Will let u know what I find. It explains how it was working before.