Guide to mains-free motorhoming
The freedom to pitch-up where you want in your motorhome is an appealing idea, but to turn it into reality you need to have a power source independent of the National Grid.
All modern motorhomes require power in one form or another for things like lighting, heating and cooking.
So, being able to survive in opulent comfort away from a mains supply requires careful consideration before you buy your motorhome and then continues with more considerations of how you use what you have to best advantage.
All modern motorhomes rely on a 12V leisure battery to power the habitation area control systems. It has been many years since the starter battery doubled up for this duty; the inability to start the engine in the morning was the reason for the evolution of ‘split charging’.
This is where a second ‘leisure’ battery is charged by the vehicle alternator through a relay, which is only energised when the vehicle is running. This ensures that use of the habitation equipment cannot discharge the starter battery.
In essence, the heavier the battery, the better.
You should not connect a wet electrolyte battery in parallel with a gel or AGM battery, because the charging requirements are different. Most combinations of parallel batteries of the same technology will work but the ideal is always identical batteries of the same age, type and capacity.
Always fit individual in-line fuses to each battery in a parallel arrangement so that, should one battery suffer a shorted cell, it cannot result in an unlimited current flow from the remaining battery.
Alternatively, use two 6V batteries connected in series, which overcomes any problems of current sharing. The two batteries must be a matched pair as far as possible. The best deep-cycle batteries are designed for traction duty, so golf buggy batteries generally make good long-life leisure batteries.
Good batteries will have published figures for both capacity (110Ah at the 20-hour rate) and lifecycle (300 cycles to 80 per cent discharge before the battery’s capacity has fallen to 60 per cent of its original capacity).
Treat any battery for which lifecycle information is not available with suspicion.
Gel and AGM batteries should be expected to provide significantly greater lifecycle performance than wet cell batteries and will cost more.
Solar photo-voltaic panels
Choose the largest you can afford and have space for, as they provide a lot of electrical independence in summer. They produce a small current during winter, and so can keep the batteries topped up all year round, which is very useful if your motorhome is placed in storage over the winter.
It's worth noting that the power rating of solar panels is based on being on the equator, in full midsummer sun with the panel facing the sun. However, on a good day in the UK, 3.5A from a panel rated at 80W is to be expected. This would be the minimum-sized panel recommended to maintain an economical motorhome in the summer.
This article is an extract from the December 2013 issue of MMM magazine. The full article includes information on power saving, other methods of power generation and much more. To buy a copy click here
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