Another thought-I would not connect anything unless it has a filtered regulated output l'm sure the Casio power supply has. I would not directly connect a 12V battery to the PX-350 since it was not designed for battery power. Would be safer to get the type of power inverter/converter that changes 12V from a car type battery to an AC outlet and plug the Casio power supply into that. I've used this approach in the field to power ham radio sets that need AC power. The converter plugs into your ci