A simple multimeter is one of those gadgets that, as an RVer, comes in handy way more often than I thought it would. Whenever one of our light fixtures goes out (which we're dealing with at the moment), or the "house" battery starts acting up, or the air conditioner motor goes on the fritz, or whatever else, being able to narrow down the source of the issue — electrically speaking — is a huge help.

The AstroAI Digital Multimeter won't win fancy awards with professional electricians or anything, but as a straightforward way to check the voltage coming off power contact points, it does just fine. It can measure DC current (though not AC), AC/DC voltage, resistance/continuity, and diodes, which is plenty enough for my needs. The kickstand, backlit display, and rubbery grip are all nice touches as well.

Get this little multimeter for just $13 on Amazon. Comes with a 9V battery and your standard black and red test leads.