Battery Charge Indicator

November 15, 20133

After installing a 12 volt outlet inside my camper, I use a battery monitor that  plugs into the cigarette lighter style power receptacle. This allows me to conveniently monitor available battery charge without crawling under the slide-out bunk, opening the battery box, and checking the battery directly with a multimeter.

Voltage Charge
12.6+ 100%
12.5 90%
12.42 80%
12.32 70%
12.20 60%
12.06 50%
11.9 40%
11.75 30%
11.58 20%
11.31 10%
10.5 0%

The chart above shows how much charge you have left for a given voltage reading. That’s right – a 12 volt battery is actually dead at 10.5 volts and fully charged at 12.6+ volts. And to prolong battery life, you don’t want to go below 50%.

You’ll want to take readings after the battery has had a chance to sit dormant for a while. Measurements taken while a device is drawing from the battery can be wildly inaccurate. For me, this means measuring after having been out of the camper all afternoon on a hike.

Extra Credit


Some RV owners will use more elaborate solutions like the Tri-Metric, monitoring not just battery percentage but also charging and discharging amps. This device truly is amazing and I encourage you to also check it out to determine what is best for your use.

Personally, I get by just fine with the simpler and cheaper cigarette lighter electric meter option. I simply plug it in to check the voltage and then unplug to a

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I've been camping regularly since I was a kid, from quick Cub/Boy Scout trips to week-long backpacking trips and everything else in-between. We got a popup camper when our kids were 1 and 3 years old to enjoy more time outdoors together alongside a few conveniences like heat and running water. Since then, we've spent over 75 nights together as a family in our popup camper. I've learned a lot about the intricacies of a popup tent camper during this time and love to share those lessons here for the benefit of others.