Review on Waterproof Digital Car Voltmeter: 2 Pack LED Display Panel for Vehicle Truck Motorcycle Boat Marine ATV UTVeter by John Springer

This item is ideal for mounting on an RV battery box to mate with a marine grade battery switch. I connected it to the positive of the battery and the negative of the circuit breaker so it only reads when the battery is on. This way I can see outside without removing the cover and using a multimeter to measure what percentage my battery is at, but the sensor turns off when the battery is off, draining the battery not during storage. The light is bright enough to be easily visible in the sun if you hold your hand over it to shade it a bit