That was already stated: "Besides, when the engine is off and there is no shore power you can see the live status of your battery."
I'm not worried about voltage drop from the battery to the cigarette lighter. Went out and measured at the battery and it's pretty darn close to the reading on the cigarette lighter. I'm not looking for perfect science here, just a quick way to determine what's going on with the batteries especially if you are boondocking.
It came in pretty handy on our pontoon boat. We would be in the middle of the lake having a good time and every once in a while I would look at the meter to make sure I had enough power to start the engine.
This was really meant for folks that don't have a clue where to start looking at battery problems. Not everyone knows what a multimeter is and how to use it. If you plug the meter to your cigarette lighter and it reads out 12v you'll know you are pretty close to having a discharged battery.
Ideally: Hook up the meter directly to the battery, check the batteries with a load tester and a hydrometer.
Don't forget the principle K.I.S.S.
2014 Georgetown 351DS
-TruCenter -Front/Rear CHF -Hellwig Links -Tiger Trak -Ran McNally GPS -ScanGauge -Truck Systems TPMS -5 Star Tune