Review on ⚡️ Waterproof Digital Round Panel Voltmeter – 2 Piece Set for 12V DC Car Voltage | LED Display | Compatible with Vehicle Motorcycle Truck Camper Caravan ATV UTV Car Boat Marine | Red Digital by Ricky Mills

I bought these battery tension units to see if my little solar chargers would keep my rarely used generator battery in good condition. Very bright even in the sun. It only took two wires and I wish it had a fusible link. Now I'm not sure, but this device could probably stay on without being unplugged. However, I install them on a key switch that turns off when the key is turned off. I just turn the key to the "on" position and monitor the battery charge. Installation, well, it's easy if you're a little skilled. You'll need to drill a hole, which in my case is metal, thin metal, and a nut will secure it in place. Wiring - A few zip ties and a loom cover the wire. I tested the device with my voltmeter and ohmmeter and the difference was within a tenth of a volt. Just be careful with the positive wire connected to the battery of this unit as it will likely actually spark if grounded and is the cause of the built in fuse.