Yeah, it seems my diode drops a half volt or a little more. I tested several old wall warts until I found one that puts out 14v/1amp. I have a small digital voltmeter wired to the battery so I can monitor the battery level, and I don't let it charge above 12.8-13v. Future enhancements include "brains" to shut off the charge at 12.8v.
I was hoping to use the iFly wall wart as a charger, but it only provides 11.9v.
The charging port is just under the switch. The inside 12v receptacle powers the SkyVector L, and the outside one is extra (for charging a phone or the iFly if no onboard power is available). It allows me to put the SkyRadar on the hatrack in the back, out of the way.
And yeah, Tesla was a mad genius. :)