Need Battery charging gauge help

Hello All - I have an 2016 Gem E6 (early year), I am having an issue with the instrument
panel battery gauge. I have installed new batteries, they take a charge fully, cart runs fine, but the dash indicator is not registering the charge. I know the batteries are fully charged because I have tested them with a volt meter. Any assistance is appreciated.

I have a similar issue on my 2002 E825. Brand new batteries, fully charged, but the computer recognizes 100% initially but drops to 65% within 3 minutes of driving. Once at 65%, the cart still drives 15 miles as if fully charged.