[Overlander23]

Kind of depends on what your HV system voltage is.

I know the Soliton-1 controller is very sensitive about low controller voltages to protect the precharge-circuit and internal contactor. I had problems running only a 12v accesory battery, as the voltage would dip too low with other accessories on and I'd get protection cut-out or a flashing warning light.

But as for DC-DC converters, I think Chennic makes a 500w version for about $100-120. Or if that's too much, people have quick and dirtily (word?) adapted PC power supplies to work. They can be had for very cheap.

Or, as you mention a laptop PS might work.

 

[OMT]

my voltage is 72 volts right now, but as soon as the car is done im going to try and build my own 144v controller so i plan to switch to 144. the controller is an alltrax so it doesnt need a 12v system