12v Supply was probably for powered option such as powered swivel seat.
There is an isolator switch on the back of the carriage (it will be near to the wall )which will isolate the batteries and allow you to turn off the charger. I would recommend you run a routine of 2 months off then 1 week on charge to ensure the batteries are kept in a good condition. Also during the week whilst it is on use the lift a few times to keep grease, gears, motors etc. mobile.
You will know when the lift is switched off as the top safety edge will produce a clicking noise when pressed, this is a special connection to the motor brake to ease hand winding – make sure nothing is holding that safety edge in or the batteries will still deplete.
