How to get 12 volts from a Cessna 310?

Tim Hickey wrote:

Thanks for the input, everybody, and Kyler is mostly right. We want to
end up with a 12 volt power source. We think that the cigar lighter
outlet, even though it is mounted in a machine that has a 24 volt
electrical system, is at 12 volts. But it gets those 12 volts by
running the current through a load dropping resister. This makes a
lot of heat, or so the owner tells me, and we wonder if anyone else
has worked around this.

Thanks again for all input.

I rewired our C152 outlet to the voltage converters output. Even though
the Lowrance Airmap 1000 supports upto 28v input. We didn't have the
dropping resistor, input to the outlet was 24v...