Can anyone explain why??

[RonS]

When I'm plugged into shore power and push the battery button it reads fully charged, and when I unplug it and push again and it reads only 1/3 charged. What is this telling me that I have a weak battery??

[Montana_657]

Yes...check the water in it lately????

On shore power the converter maintains about 13.8 volts, a full charge. Off shore power the battery carries the load... or tries to. Your battery is in pain....makes sure it's full, if that doesn't work or swap it out for a new one. Remember to check the fluid (electrolyte level) every so often.

[stiles watson]

If you are having battery trouble and need to replace it, you might consider switching to "golf cart" 6 volt batteries wired in series. Happy RVing..

[sreigle]

Sounds to me like Gruffy is right. On shore power you have converter power to the battery and that's what's giving you the full reading. The 1/3 reading on battery power is telling you the battery is weak. Check and refill the water (don't use tap water) then check it again after a couple of days hooked up to shore power to get it charged back up. One day might be enough. I'm not sure how quickly these converters charge the battery.