12V DC Voltmeter Color LED Digital Display - Waterproof Volt Meter Voltage Scale Gauge 5-15V Battery Tester for Marine Car Motorcycle Truck Boat RV without Panel, Directly Install or Replaced on Panel

Update July 29th 2021: Still going strong coming up on the end of its second season in service.I find this is my go to even though I have a dedicated voltage gauge on my dash, and a voltage readout on my fish finder. The problem with them is the voltage drop caused by the wire run up to the dash and the fact they share the circuit with many other devices. This causes them to always read lower than the voltage at the battery terminals. This is installed in the battery box and gets its power directly from the main disconnect switch. The main disconnect is connected by a 1 foot 1 awg wire direct to the battery which results in negligible voltage loss.-original review-It was an easy Install in a boat battery box.Set it up so any time the boats main power switch is on then its on. My only complaint with this is the green bars can be kind of dazzling at night making it slightly difficult to read the rest of the display. Not something I would want right on my dash or in my main field of view will boating in darkness. I've had it installed for a season now, and have had no issues. It is slightly sheltered from rain but it definitely gets water on it here and there.The bar graph is graduated intelligently. If all you have are red bars your battery has reached its 50% discharge. (I know i'm not accounting for load so that is not 100% accurate) 50% is usually as deep a discharge you wanna put on a deep cell going more than that will start to shorten its life span.If you only got a couple red bars there's a chance that the motor isn't gonna turn over. If you have orange bars you're in great shape nothing to worry about. Green bars the battery is fully charged. Flashing numbers, your battery is being over charged.The simplicity of the color coding is my favorite part. My boat, which is also used by my brother has one 100 amp hour marine battery on board which does everything. Keeping an eye on voltages is important but with this thing you don't need to memorize numbers. Because the boat also has an unregulated charging system its possible to over charge the battery which the flashing indicator is excellent for grabbing your attention in that situation. It lets you know you need to start burning some extra juice like turn on the nav lights or something. It gives me peace of mind when my boat is being used by someone else that they have an easy to decipher indication of the battery's status. Even for me whos stared at plenty of "voltage vs charge remaining" charts Its still nice to be able to get a situation report with a quick glance and not have to think too hard about it.

I don't need a full blown multimeter with a shunt for my purposes. I need something to give me an idea of how much voltage I have left in my battery. This provides just that. Easy to use and install. I put an on/off switch on mine because it is bright, and makes the camper bright at night.

Using it for my tractor and love the fact that it is very accurate and displays the red, yellow, green colors according to the standards for lead acid batteries. The display correctly shows all green lights at 13.5 Volt and it starts flashing when the Voltage exceeds 15 Volt (over voltage).

Happy with and installed in a few areas of my boat.

Car trailer battery voltage so I can see if it’s is changing from the truck