Marine Ac/Dc attempts to answer your questions about boat wiring and marine electrical techniques, concepts, and products. We get lots of mail from folks in mid-project or who are just curious about their boat’s electrical setup.

There are loads of post already on the site which we hope you will browse through. If you’re trying to track down info about a more specific category, please use the search box in the upper right of this page or check out the list of various subjects farther down on this page.

If you aren’t able to find the info that you need to complete your particular boat wiring project, please send us an email at boatwiring@gmail.com.

Thank you for visiting. We look forward to hearing from you and hope that you will be able to come back often.

Kevin,

I tore all of the boat wiring out of my 1989 Champion. I have all new gauges and a new marine electrical switch panel.

When I attempt to hook up the new stuff to the – and + battery terminals, I get big sparks and smoking.

Have you got any suggestions?

Thanks.

George

Hi George,

It sounds like there is a directly short to ground in your marine wiring.

Follow the + wire from the boat battery to the distribution. Check for proper connections on switch lights and crossed connections on gauges.

When you fix the problem, I strongly recommend adding circuit protection at the battery. It will trip before the smoke gets too thick.

Good luck,

Kevin

Hi Kevin,

I’m interested in researching the option of total rewire and upgrade of all marine electric components on my Arima Boat. Do you have schematics and or history pin this particular builder that might help in assessing the scope of this project?

My goal was to incorporate complete new wiring and grounding as well as eliminate old wiring from previous owner and install at factory with state of industry tinned marine wiring and boat bus bars.

Thanks,

Paul

Hi Paul,

Boat wiring diagrams are very rare. We do not have access to any information for your Arima.

Most people choose to create a harness from scratch using a standard marine wiring color guide and the bulk wire. The other option would be to purchase a snap together boat wiring system from one of our retail sites.

Hope this helps,

Kevin

Kevin,

I am converting a barge into a houseboat/floating home.

I like the Easy Add AC Shore Power system that you designed for your retail marine electrical site, but want/need more electrical outlets to power things like computers, microwave, etc., etc…

Do you have a system that will handle more outlets or can you can you point me somewhere that I can find the information.

Thank you,

Ted

Hi Tim,

The complete shore power system can be expanded to as many outlets as you wish.

The limiting factor is the 20 amp main breaker. If 20 amps is not large enough, I would take a look at the panels that are available from Paneltronics. Their systems are not snap together marine electrical like ours, but they do offer a wide variety of AC panels.

Thank you,

Kevin

Hello Kevin,

Thanks for all of your really helpful boat wiring advice.

I am rebuilding my boat battery wiring to add a dedicated house battery system.

I want to use six 6 volt lead acid batteries and want to wire them in a series/parallel configuration – but am confused about how each battery is inter-connected with the one next to it. They will sit in two rows of three batteries each.

Would you have a boat wiring diagram showing how to wire this up for six marine batteries?

Thanks,

Charles

Hi Charles,

Dedicated house battery systems are becoming more popular in marine electrical and for good reason. They can really help with power management and – more importantly – can make sure that you can start your engines to get home after a long day playing. This is especially true of boat battery wiring that includes an automatic smart boat battery switch.

Here is a boat wiring diagram that should help your with your project.

Kevin

Hi Kevin,

I hope you can help.

I have a Mainship with two engines, each with an alternator. Each engine is wired to a marine battery switch (1/2/All/Off) and each switch wired to a separate battery bank. The switches have a solenoid between them so that I can start the engines/run the house from either bank.

I’d like to replace my 12 volt fridge and would like it to have it draw from both banks. Can I set up the marine electrical so the fridge is wired to both banks? Or will that negate the separation provided by the solenoid? Maybe I need a selector switch for the fridge?

Thanks,

Manny

Hi Manny,

The simplest solution would be to wire the refrigerator to a separate boat battery switch.

Keep in mind that when the switch is in the All position, you will be paralleling both house battery banks. With this in mind, you will want to you at least the same size boat battery cable that is currently used to connect the banks to the existing switches (positive and negative). Using a small wire would be a potential fire hazard.

A solenoid system could work, but it would be considerably more complex to wire.

Hope this helps,

Kevin

Kevin,

I think that I need to add a marine electrical bus bar to my boat battery wiring.

Do you have any recommendations and or an installation diagram – or are these mainly for the boat battery switch systems that you have on your boat wiring store?

Thanks.

Phil

Hi Phil,

A heavy duty boat bus bar will work great as a common ground for your entire marine wiring system.

Connect your negative boat battery cables and all of the boat grounds to it. This will reduce the number of battery ground connections to one on each boat battery.

Hope this helps,

Kevin

Hi Kevin,

I hope you can help me with a boat wiring issue.

On my boat battery wiring, I have two batteries for my trolling motor, a 24 volt Motorguide. They are hooked up

• + to motor
• - on battery to + on 2nd battery
• - to trolling motor

The on board marine electrical battery charger has connections for two batteries. Do I just hook it up positive and negative on both batteries?

The reason I ask is the in line fuse on one battery was blown as I took it apart today.

Thanks

Dean

Hi Dean,

Most dual output battery chargers are designed to be connected the way you had them.

The blown fuse may just be a fluke or your charger may not be designed to charge your batteries in series. Check with the manufacturer’s recommendations. If they say 12/24 volt systems, then you are good to go. If not, you will need to disconnect the batteries to charge or buy another charger.

Kevin

Kevin,

I need your boat wiring assistance.

On the installation of a Guest 2501 model battery isolator is the existing boat battery wiring at the battery terminal of the alternator left on the alternator or is it transferred to the main battery terminal of the isolator?

Thanks for all of your marine electrical advice. It’s really appreciated.

Jerome

Hi Jerome,

Thank you for the kind words. I’m glad that you can use some of the marine electric articles that we post.

As to your boat wiring question…

Yes.

The main alternator output is removed from the alternator and a new conductor will run from the alternator to the isolator.

Have great weekend,

Kevin

Kevin,

I’m in the process of installing the automatic smart boat battery switch that you designed for EzAcDc Marine Electrical.

On your boat wiring diagram it shows that the boat battery wiring coming from the batteries to the marine battery switch, are 2 AWG ( red & black). The wires coming from the switch to the VSR are 8 AWG.

The cable from my motor, a 50 HP Mercury, are 6 AWG.

Do I use the size wires as shown, or can I use a 6 AWG throughout the complete wiring ?

Will it still work safely ?

Thanks

Rob

Hi Rob,

As you increase the boat battery cable length, you will need to increase the boat battery wiring size to reduce voltage drop.

Mercury provided 6AWG cables with your motor with the assumption that it would be connected directly to a battery or to a boat battery switch with minimal voltage drop. If you use 6 AWG cables from the marine battery switch to the batteries, you will induce a larger voltage drop and may cause your engine to not start.

Running 2 AWG from the batteries to the switch will help reduce the voltage drop to the engine. Another option would be to run 4 AWG from the engine to the battery switch and 4 AWG from the switch to the batteries.

Hope this helps,

Kevin