Narrow Boat Batteries Explained – With Video!
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Wed May 6, 2015 at 10:27am

Narrow Boat Batteries

Many of our potential customers ask us about how the batteries work on a narrow boat. So in this article we will explain the two different types of batteries you have on board and how they are used.

The physical size of the battery unit does not affect the ratings or the performance of the battery. The batteries provide you with the main source of power for all your electrical appliances on your boat.

Starter or also known as a Traction Battery

The starter battery is designed to deliver a large amount of power in a quick period of time. This is perfect for when you are trying to start the engine. A cold engine will need a large amount of power to get the engine going.

Leisure or also known as a Deep Cycle Battery

With leisure batteries you will have a bank of batteries sometimes 3 or 4 batteries together. The leisure batteries run your day to day appliances such as your water pump, cooker ignition and lights etc. Therefore they need to deliver power over long periods of time.

Leisure batteries have a voltage of 12volts not 240volts like in a home.

The two types of batteries are kept in separate banks, typically on opposite sides of the boat.

The batteries are kept apart for a good reason; the leisure batteries can be drained when they are trying to maintain the entertainment systems and other appliances within the boat if running for a long period of time. If this does happen you can then rely on the starter battery to start your engine and to recharge the leisure batteries.

The Isolator Key

Isolator keys are used to keep the power stored in the batteries away from the circuitry. It also helps to avoid the batteries beginning drained when the equipment is left unused over long periods of time.  

Watch this video which explains the differences between the two sorts of batteries used on a narrow boat...


Judith Green | Mon Aug 21, 2017 at 3:17pm
Can you recharge batteries on devices (ie computers etc.) by using a regular plug in during the day while the engines are running ?
Whilton Marina | Mon Aug 21, 2017 at 4:39pm
Hello Judith,The ideal senario is to have a 12 volt battery system, with an inverter which changes the current from 12 volt to 220 volt and would allow you to charge a computer or other items on board the narrowboat just as you would in a house.
Kendall Riehl | Thu Jul 18, 2019 at 10:57pm
My low battery alarm keeps going off. My narrow boat is connected the marina electrics. This should keep my battery charged. When I start my boat the alarm stops for about to 4 hours. What is the problem and how do I find the cause?
Whilton Marina | Mon Jul 22, 2019 at 11:33am
Hello Kendall, Your battery problem could be one of a number of things; it could be an ignition fault, a battery issue or an alternator fault. We advise that you get a marina electrician to assess it for you.
Mandy | Sun Sep 6, 2020 at 12:43pm
Hi, I’m wondering if you could help me, my battery blew up when I used the bilge pump, I have replace the battery and I still have no electric, any ideas why I can’t get 240 electric? Regards Mandy
Whilton Marina | Mon Oct 19, 2020 at 4:50pm
Hello Many, There could be several reasons why you have no electric after your battery problem. We recommend that commission a suitably qualified electrician to look at the problem.

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