I've got 3 of those..
One (sealed Fios) on the tracking mount and two indoors, on old SUV batteries, also sealed.
Using 5W PVs, they keep batteries at 13 to 13.4 volts. Even when there is no usage.
When the green
CHARGED LED comes on, they might stop charging..
I supect some models might have an over-charge preventer built in..