The poor battery maintenance you describe will cause any forklift to stop! opportunity charging gives a false reading, and the voltage drops too low, truck stops because electric brake has no power, and stops dead...your nose into screen! The brake is spring loaded, on all the time, until the computer powers it off. Poor maintenance alone will cause the truck to stop. Could be any brand!
Battery needs 8 hour cycle charge, 8 hrs to cool, then used until it's dead again. That's one life. Charge it here and there 20 mins, that kills the battery and makes it unsafe for anyone to use