The QRPer Board

Any risk to the radio running a 12v battery? I have a vague recollection of reading of a potential issue if using a 12v battery. The facts get increasingly vague every year!

I believe the sw-3b will run anything between 8 and 15 volts. 12 volts shouldn't be a problem.

I've run my SW-3B on LiFePO4 voltage (13+) just fine.
73 Skip K4EAK

From the SW-3B Manual (http://venus-itech.com/download/SW-3B%20Manual.pdf)

Operating voltage: 8-15VDC

I think you should be fine with a 12V battery. I'm planning to get one of these at some point and I'll probably run it from my Bioenno batteries.

The vague recollection you may be having COULD be because the MTR series which is a similar form factor has warnings in its manual regarding voltages over 12V and states:

Supply voltage 5.5 volts minimum, 13 volts maximum. 6 to 12 recommended.