POWER TALK

With so many new people discovering the delights of motorcaravanning, internet forums are awash with questions about the electrical systems in your motorhome.

Many are complicated technical questions, but just as many are basic queries, such as “What can I run off 12V?” and “Why don’t the 230V sockets work when I’ve switched on the control panel?”

So it’s time for an overview of the key electrical systems in a ’van, how to diagnose problems, how to be electrically frugal and what to upgrade.

Begin with the basics

All modern motorhomes and campervans work in a similar way. They have two types of battery: a base vehicle battery (often in the engine bay or somewhere in the cab) that powers all of the base vehicle electrics, and a leisure battery (kept somewhere in the motorhome interior or under a seat) powering all of the habitation electrics – from the LED lights to the fan in your heater, it all runs off 12V DC.

When you plug into a mains hook-up, the 230V AC flows into your three-pin sockets and activates a mains charger to keep the leisure battery topped up. So your 230V sockets won’t be active unless you’re plugged into the mains.

Some appliances, such as certain fridges, automatically switch over to mains power when you’re on a hook-up, to save energy. If you want 230V power independently of a hook-up, you’ll need an inverter (see issue 246 for more on these).

Some motorhome mains chargers also charge up your base vehicle battery – it’s wise to add a charging device if your motorhome doesn’t already have one.

Leisure batteries and base vehicle batteries are also charged up when you switch the engine on and the alternator (a belt-driven AC generator) rotates. A charging circuit – of varying levels of efficiency – then transfers current to both the starter battery and the leisure batteries.

Both sets of batteries can also be recharged via a solar panel on the ’van roof. Typically, these will only work when the engine is off, but it depends on how they have been wired in.

A common problem for newbies

Easily the most common problem for motorhome first-timers is assuming either the mains systems work all of the time, or the electrical capacity is identical to that of your house. “I plugged in my kettle and toaster, so why don’t