How to Wire a Boat Battery

What You'll Need
Soldering iron
Wire strippers or knife

A boat battery is a very important part of your boat's electrical system. Most boats have two batteries, one to start the boat and one to provide power for the electrical equipment. Wiring up these two batteries can be tricky if you're not sure exactly what to do.

Step 1 - Buy the Batteries

When buying batteries, you must make sure to buy reliable marine batteries instead of car batteries. Car batteries are not suitable for use on boats, as car batteries won't last long enough. Secure the boat battery with a strong strap inside your boat to prevent the battery from coming lose when waves pound your boat.

Step 2 - Buy the Wires

Next you need to buy wires to connect the batteries to the electrical systems in your boat. The wires used to connect the batteries will be the longest and the highest-rated wires in your boat. You should use the type of wire recommended by the manufacturer of the boat battery. Using 6- to 8-gauge wire will ensure that the wires don't get too hot.

Step 3 - Connect the Boat Battery

Now you will need to connect the boat battery to the electrical systems in your boat. To do this, start by connecting the negative connection because this will avoid any problems or danger. If you connect the positive terminals first, you can cause sparks when you complete the circuit. It's a good idea to use color-coded wiring so you can easily troubleshoot any problems with the electrical systems on your boat.

If you need to connect a second boat battery, you can choose from either option below.

Step 4a - Connect the Second Boat Battery in Series (Optional)

If you need to connect an additional battery, you can connect the batteries in series with one another. Connect the neutral terminal to the positive terminal of the second battery. And then connect the loads to the positive and negative terminals on the battery. Connecting the batteries in series will not make your batteries last any longer; however, they will produce more power this way. Consequently you can power many more appliances at the same time.

Step 4b - Connect the Second Boat Battery in Parallel (Optional)

Another option, instead of connecting the batteries in series, is to connect them in parallel with one another. This setup offers an advantage that the first option does not. Connecting the batteries in parallel will allow the batteries to last longer before you need to charge them. However, unlike the first option, connecting in parallel will not provide any extra power to run more appliances.