Good luck with that. I'm suspecting the D. Ken PSU. You can run the IIc off a small motorcycle or burglar alarm system lead-gel cell battery, it runs off 12V to 15V as I remember. The IIc uses a 65C02 which can as low as 3.5V as some of the other CMOS Chips as well. Its the ports and disk drive requires the higher voltages. But being CMOS, stray signals can go right through them.

Look over this you-tube vid on how this guy did it.