RE: 14MZ battery charging
The charge ports are used when you use the failsafe switch instead of mechanical switches. When the failsafe switch is used, both batteries are connected directly to the unit, no mechanical switches. The failsafe switch plugs into a special port and turns on/off both batteries. Since you have no mechanical switches in this case, the charge ports are the only way to charge the batteries. When you use mechanical switches you would use the charge port in the switch and the MZ charge ports would not be used. Please let me know if you have any other questions.