Read the charger, and/or the back of the piece of equipment you want to use, it will tell you it's input/output voltage. Most (if not all) plug in electronics can be used in 24v cig outlets, and all modern cig adapters have a fuse built in. I use my GPS unit plugged in all the time, and tablet chargers, phone chargers etc in the 24v outlet.
I don't want to hijack this thread but maybe I need to review the electronics side of things. I have a 24v JDM HZJ73. And it sounds like yall are saying I don't need to run chargers through a converter for standard electronics in the US... Then when do you need to run a 24v to 12v converter?
I killed a Midland handheld CB radio plugged into the 24v in mine.