That's good... My guess is you have battery issues. The charger will take the pack up to 42-44 volts it will settle overnight to 38.4 = 100% capacity... 50% discharged is 36.1v that is as low as you should go....
One weak battery can cause the problems you describe. Anytime I have to add more than a gallon to 4 batteries I suspect irreversible damage... they have either been charged while low on water
or left for a long time at a low voltage or state of charge.
Either way is damaging...
You can get a Hydrometer at the autoparts store and check them 12 hours after the charge and see what you got....