Article: Motorhome electrics - the very basics

For people who are new to motorhoming, or those wishing to buy, and have very little understanding of how the electrical system of a motorhome works, here is a little about the basics.

Your motorhome will usually have three basic electrical systems integrated. The 12 or 24 volt system to power the engine and running gear, the house system which runs some of the "house" type items like lighting on 12 or 24 volt, and a 240 volt system to run the bigger household items. You should have two separate battery systems - one to start the engine and the other to power the house system.

The engine system is the system in your car where power is held in the battery, and charged by the alternator when the engine is running. The battery needs a high power draw to crank the engine then is almost not utilised once the engine is running. This type of battery does not handle a heavy draw over time. If set up correctly the alternator can also be wired to charge the "house" batteries whilst the engine is running then automatically shut off to ensure you only draw on the house batteries when parked and do not drain the start battery.

The "house" system runs everything except for starting of the engine and running of wipers, headlights, etc. This is usually a 12 volt DC system where appliances can run from your "house" batteries. These "house" batteries (of which there may be more than one) handle a draw down to a much lower level than the start batteries. You will then have a 240-volt system that is powered direct from a 240-volt hook-up, or by an invertor or generator. Appliances like lights and water pumps are usually 12 volt. Many other appliances can now be purchased as 12 volt appliances. Mobile phones have now become an essential accessory and can also be charged by 12 volt cigarette lighter adaptors.

Larger appliances like TV's can be 12 volt, or 240 volt if you have an invertor. 12 volt TV's, video players and DVD's are much more expensive than the "dime a dozen" 240 volt versions so an invertor may be a good investment if you want all these. Do not be fooled though. Just because you have an invertor, do not think you can use you electric toaster, electric jug and hair dryer. If the appliance has a heating element, it will draw a very large number of watts. Unless you have a large invertor and battery bank, your system will not cope. Cook your toast and boil your kettle on the gas stove top and leave the hair dryer at home, or plug it in when you are in caravan park amenities only. A microwave will also draw a lot more than the 800 or so watts advertised in the brochure or in the store. Look at the compliance plate on the back of the microwave to get a true reflection of the watts drawn.

Your set up will depend on the type of travelling and living you wish to do. If you intend to travel from caravan park to caravan park and always have 240 volt plug in power, your system will be very basic with all 240 volt appliances. Whilst this may be a cheaper option to build, it gives you very little flexibility and makes for more expense in the caravan park fees every night.

The other extreme is completely self sufficient with either solar and/or generator power. Generator power is not environmentally or neighbour friendly. The cost of the diesel or petrol needs to be taken into consideration to run the unit for several hours per day. Solar on the other hand is a large cost up front with virtually no running costs. These vehicles can stay away from 240 volt hook-ups for indefinite periods.

Then there are the setups that rely on solar for a few days, but do need to be plugged in, or have a generator run whenever the power runs low. This is a good compromise if you plan to travel and have the alternator charge the batteries every few days, or you are happy to stay in caravan parks or other 240-volt sources when ever you run low on power.

A great resource for further, more in-depth and accurate information in an easy to read format is the Motorhome Electrics book by Collyn Rivers. Click here for a link to his book.


 

 

© 2008 Gail Bennett (motorhominglifestyle.com). If you would like to reproduce this article on your website please contact gail@motorhominglifestyle.com