Per reminds us of a couple good points. Many devices report on the back that they want 12v DC input. It's good to check on the actual range of acceptable voltages. While recharging the batteries, the batteries, and thus the plug sockets will see about 13.6v DC.
And if you have a battery charger that de-sulfates the battery, you'll see an even higher voltage. Usually, one should disconnect any 12v appliances during de-sulfication. (Even a turned off unit is using some small amount of current to maintain radio presets and the clock and alarms.)
Many devices intended for 12v usage from the start will tolerate quite a range. But 12v from a 120v brick
might be better regulated.
I've seen 12v plugs with an internal "regulator" to keep the output to 12v. I should have bookmarked the address. My vague recollection was that this was in relationship to those units that plug into a socket and output a variety of voltages according to how you set a switch. The specifications will say whether the 12v is regulated, or whether in it's 12v state it'll just pass through what it's getting at the socket.
As I type this, I did a little side trip over to the Shack. The owner's manual for this device says that the 12v output is regulated and it comes with a number of adapters.
http://www.radioshack.com/product/index.js...995&tab=supportIf you thought to go this route and you can't find out the tolerance range for the device, I'd go for one of the regulated multi voltage units. They usually have a variety of plugs to choose from. Pay attention to "tip positive" or "tip negative".
Note that I suggest you would use this device plugged in to shore power or not. Why carry an adapter and a brick both. Or a brick and an inverter both.
Personally, I'm slightly averse to inverters and their (usually) 10% wasted energy.
As for 12v plugs and receptacles, I use Marinco marine units when I add a socket. The receptacles have a couple "dents" on the inside into which the Marinco plug "ears" will catch into and keep the plug firmly attached. Plus, the plugs have a rubber seal around the body to seal the plug against the weather and to help hold them in place. You just rotate the plug 90 degrees and pull to remove the plug. The plugs work no worse than ordinary plugs in other sockets.