2005 GEM battery display on dash always shows single red line

[Inwo]

Battery display always indicates empty (one bar)

Hi everyone, I have a 2009 GEM el xd and the battery display is now always indicating it’s empty showing only 1 red bar out of 10. The charger is still working and I’ve verified that the batteries are fully charged using a voltmeter and I was able to drive it around for hours without it dying. What could be causing this issue where the dash display is failing to read the charge on the batteries? Is there a connection that needs to be cleaned? Thanks in advance for any help!