Bill, I had the same consern about running from a 13.4 or higher battery.
I found some very inexpensive voltage regulators that will reduce the higher DC voltage to what ever you want it to be. They are rated for 3 Amps.
So getting 9 or 12 volts DC from that LiFePo battery is easy.
On Amazon they are listed as:
LM2596S Buck Converter Buck Module
