Boat Voltmeter Wiring Guide: Hook Up Voltimetear Easy And Fast


If you are a boat owner, a voltmeter is one of the accessories you want to be installed in your vessel. Not only will it allow you to track the amount of electric power running through the boat’s electrical system but also helps you determine whether the battery is working properly.

It may not make it to the top ten items in your boat safety equipment checklist but could surely help you identify potential problems with your battery so you can prevent future power failure while on the water.

Here is a quick guide on how to hook up a boat voltmeter to keep you in the know of your batteries’ performance and the charging voltage. But first, a thing or two about voltage and voltmeters.

Voltage And Voltmeter Explained

Many boaters use the word “voltage” without really understanding what it is. Voltage is not current, that is, it is not the movement of electrons from one point to another. Rather, it is your boat’s electrical system’s ability to move electric charge from one point to another.

Think of it as a hose pipe – the water that flows through the hose is the current and the pressure that enables it to flow is the voltage. If your boat’s electrical system has no voltage, then there would be no current. Voltage is therefore the measure of the difference in electric power potential between one point and another, and that is what a voltmeter measures.

Your boat voltmeter will have two terminals, usually connected to “leads” or wires. Let’s say you want to measure the voltage between points A and B. All you need to do is place the end of one lead or wire at point A and the end of the other at point B and the voltmeter will display the difference.

How To Install A Boat Voltmeter

Below are easy steps on how to hook up a boat voltmeter to ensure that your battery is in tip-top performance.

You will need:

  • Duct tape
  • Spade terminals
  • Wire crimper
  • Sandpaper
  • Screwdriver
  • Hole saw

How To:

  1. Think about where you will be installing your voltmeter: Your meter should be mounted in a place that is easy to see. One important boating safety measure is to always keep your eyes glued to where you are going. You don’t want to place your voltmeter too far away that you are forced to take your peepers off your boating route to get a reading. On the dash, and especially above the boat’s steering wheel will be a good place to do your installation.
  2. Examine the dash area where you plan to install the voltmeter: This will ensure that no wires are damaged during the process especially when you are drilling a hole for the meter. If you can push out wires out of the way, do so but make sure they are held back with duct tape.
  3. Cut a hole in the dash for the voltmeter: Using a hole saw, drill out a hole in the boat’s dash where you will be mounting the voltmeter. Grab sandpaper and smooth the edges of the hole to give the voltmeter an easy entry into the dash.
  4. Attach spade terminals to the voltmeter wires: Your voltmeter will have three wires coming from it – background wire, red power wire, and white wire that lights the voltmeter. Use a wire crimper to attach spade terminals onto each of these wires.
  5. Start your writing: You will start your boat voltmeter wiring by loosening the screws of the power inlet serving the closest instrument to the voltmeter. Once you have created enough room for the red power wire, push its spade terminal below the screw and drive the screw back into its original position.
  6. Connect the voltmeter’s light: Here, you will be using the light terminal of the gadget next to the voltmeter. What you need to do is connect the light wire coming from the voltmeter to this gadget, as this is what will provide light to the voltmeter.
  7. Connect the ground wire: Using a screwdriver, unscrew the ground terminal on the adjacent instrument. Push the spade terminal connected to the ground wire under the ground terminal and drive the screw back.
  8. Switch it on: Turn the power switch on the voltmeter to “on” and you will have your battery voltage information displayed on the meter’s screen. The voltage of a completely charged lead-acid battery will range from 12 VDC to 14.4 VDC. If you are checking the voltage of a gel-cell battery, then the voltage displayed will range from 12VDC to 14.2 VDC.

Important safety tip: Always have the negative cable of the boat battery disconnected before doing any installations to prevent accidental starting or even worse, electric shock.

You might also like: What Should You Do If Your Small Open Boat Capsizes?

How To Read Your Voltmeter

Now that you are done with your boat voltmeter wiring, how do you take a reading? Well, some boaters prefer keeping a constant check on their meters when the boat engine is running while others prefer taking their reading when every accessory is switched off.

Depending on your boat type and the battery you are using, the voltage displayed on your meter will range from 13.2V to 13.4V and 10.5V to 12.6 V respectively. A reading of more than 14.5 V while the boat is underway or 12.2 V in the open circuit indicates a problem with the boat’s charging system.

Globo Surf Overview

A problem in your boat’s charging system can turn a fun-filled boating adventure disastrous. Good news? With gadgets like voltmeters, you can be able to identify existing and potential issues with your battery and fix them before they escalate. And you don’t have to be a rocket scientist to install one in your boat. Just obtain the necessary instruments and follow the above simple steps. Trust us, the entire process will not take you more than 10 minutes!


  1. How To Wire A Voltmeter