Review on 🚗 MICTUNING LED Digital Double Voltmeter: Round Panel Voltage Monitor Blue for Cars, Pickups, RVs, Trucks & Dual Battery Packs by Ted Boone

As others have pointed out, the display is difficult to read in bright light - much like your center console with the sunroof open. It reads voltage not current so any wire can be used to connect it, I used a spare CAT 5. I wanted it to turn off when the ignition is off, so I connected a relay to the ignition and used the relay to turn on /off the ground - turning both displays on/off. [You can use any switch for this.] Runs like a champ - I can see when the battery breaker kicks in and charges the backup battery.