Narrow boats use direct current, or DC, electricity to power lighting and some appliances in the way of 12v or 24v. Here we look at why and the benefits and limitations of this type of electricity on a narrowboat.
DC System… Electrical Theory
In a DC circuit, electricity flows in a constant direction. We use DC in low voltages on a narrowboat simply because the method of storage and transportation of power we traditionally use, batteries, can only produce and store DC current.
The conventional narrow boat 12V system we are familiar with was originally developed and refined during the early days of automotive development. Our systems have simply adopted and refined existing technology.
Narrow boat DC systems can also be 24V or a combination of 12 & 24. We see in the ‘Battery Section’ how 12V batteries are a collection of 2.2V cells and although the actual voltage of a 24V system is technically higher, we refer to the more familiar 24V term when describing these systems. The restricting factor for 24V is the availability of appliances rated to run on 24V. Again in the ‘Battery Section’ we see how 24VDC systems can be advantageous when running long cable runs to appliances such as pumps or motors as the wiring costs can be kept down. 24 volts can push current amps along thinner wiring. However as 24V appliances can be more expensive in the first place, and you have the added complexity of a second DC circuit, you should think hard about whether the benefits outweigh the costs.
A rectifier can be used to obtain DC from an AC supply, such as used in an engine alternator. An inverter can be used to change DC into AC, such as when we require on-board power for a washing machine when not plugged into shore power.
DC System… What Do We Use It For?
We are not discussing inverted power options in this section purely in an attempt to keep things simple and to discuss them in a logical order.
Firstly, it is possible and commonplace for a narrow boat to operated very comfortably without any AC or conventional mains power. Shock horror, we hear many of you exclaim but it wasn’t many years ago that the majority of boat were constructed for leisure purposes with no consideration towards “household” type lifestyle.
For many, the simplicity of just getting away from daily life and all the modern technology we seem to require is what floats their narrowboat. If you can do with out a washing machine, tumble dryer, microwave or a dishwasher then there is really no need for mains power, inverters or gen-sets.
Portable clothes washers are available to keep on top of the “smalls” and there are some really good resources available which map the location of launderettes around the system.
12v DC hairdryers are available but not particularly efficient & here-in lies one of the issues we find with 12VDC systems. Anything with uses an element or a large motor for power will be a tremendous burden on batteries & wiring and therefore really should be avoided. It’s at this point, if you really need home comforts such as the above mentioned microwave, that you need to look at AC power.
And at this point we bring inverters into the equation. See our section below for more detailed information. We can also use DC power to run AC appliances. An electronic gizmo called an inverter is used to convert power from your battery bank to AC mains type power to run all the other things we need.
With DC stored in a battery bank, our systems are limited by the power output of the batteries and the equipment available to use able to run directly on DC. Typical DC appliances commonly found in canal boats include refrigerators, freezers, radios, televisions & lighting.
Laptop computers and mobile phones & dongles can all be charged from DC batteries. 12v DC is used as the ignition source in heating and ovens/hobs and is used to power TV signal boosters.
Remember that what we take out of a battery has to be put back in again so if DC power is all you feel you need there will have to be a bit of adaptation from conventional land based living. In fact, even if you’re lucky enough to have the most technologically advanced marine systems on your narrow boat there is still a degree of lifestyle change that should be worked through.
Not what you're looking for? Try some other items within this chapter...