It's a Yaesu FT60R. In the manual is says that external 6-16V DC is acceptable. I know the car DC outlet puts out 12V so it's well in that range. I also found out, then when you plug in the power adapter tip into the radio, it disconnects itself from the battery power. When in the radio, it won't power on even though the batter is charged. So the actual charging circuitry must be internal to the radio and not in the external power adapter.
I did a lot of research on the web and found that this seems to be common for this radio. Several youtube videos showing all kinds of power adapters that people made for this radio.
I also found this thread in the process: http://forums.qrz.com/showthread.php?208775-Yaesu-FT-60R-DC-power
I don't plan on running it this way a lot, just when I am low on power.