Do yourself a favor
#1 Get a volt meter…BUT DONT do what I did.
I got a really good Fluke (brand ) it's a pro tool, love it. But it's for ELECTRICIANS….and it registers in one volt increments, because electricians don't care about tenths of a volt. I need to know my Batt range from 12.0 to 12.8 volts resting, AND 13.8 charging
#2 Get yourself a small plug in AC polarity checker 3 or 4 bucks ? They tell at a glance, which AC wire is broken, which wires are touching, and if the wires are switched. I have had switched polarity at campgrounds, or switched polarity of extension cables. When you touched my camper while barefooted, you got a shock. Luckily, I have an old trailer with a warning light on the outside of the trailer
#3 A cigarette style plug in DC volt meter. You can tell at a glance if charger is on and what your batt voltage is. ( you still need a portable volt meter for checking stuff)
#4 tools- philips and flat head screwdrivers, wire stripper/cutter, knife, electrical tape