We use 120 volt chargers when we have shore power, of course.
We have a couple 12 volt
cigar lighter chargers for when we're not on shore power. I was able to find one on Amazon that has a USB socket that can charge the iPad, too. We have at least 3 iDevices with us when camping (our phones and Erica's iPad, but there may be others), so plugs that have two USB connections are best.
We also have an iPod connection for the radio that I installed. I got it off Amazon (I think this is it
) and had it in her car before we sold it, and I pulled it and installed it in the camper. This allows us to use an iPhone to play music through the radio, and it allows us to charge the iPhone even if we aren't playing music (I don't remember for sure if it produces enough power to charge the iPad).