J wrote:

We have one. We built a little box that has a 3 way cigarette adapter
from radio shack. The box goes down by the seats and is powered by a cord
that plugs into the aircraft's cigarette lighter. The box also houses a
28-14v converter since our aircraft is 28 volts.

Did the same thing in the C152 (24v), but put everything behind the
panel. Bottom part of the radio tray is velcro'd in, so its easy to
remove and plug in the cellphone charger, notebook, etc. The converter
supports 15 amp, 10 amp continuous and is break'd through the original
power outlet and also fused. Max draw is 7.5 amps...