In order for your ’van to operate away from a mains socket, many of the electrical systems are designed to work from a 12V battery. When you are on a site, the battery is charged from an electric hook-up
and when you drive, your vehicle alternator takes over the charging.
Battery charging is a complicated business and there are plenty of opinions,
as well as facts floating around regarding how best to do it. There is one certainty: having more battery power available will help you enjoy your break.
Battery basics
Before we get too involved
in how to charge a battery,
you should first understand how batteries work.
Batteries are sensitive things and they need to be coaxed into providing the best service.
Throwing a constant voltage at a battery in the way that a standard alternator or cheap battery charger does will typically only charge it to around 70 percent of its capacity. This means that your 85Ah leisure battery could only be putting out 60Ah.
To make matters worse, as far as your TV or fridge are concerned, your battery is effectively empty when there is 40 percent charge left in it, so in real terms you could have as little as 35Ah of useful power in your 85Ah battery. Another downside of this constant voltage charging is sulphation of the battery. Many people will opt for a larger leisure battery to increase their reserve of 12V power,
but all they will have then is 70 percent of a 110Ah battery.
Many batteries are replaced because they no longer accept a charge, which people put down to the battery being exhausted, but the truth is that a layer of lead sulphate has built up on the battery plates, which prevents them taking a charge. Charging at higher voltages prevents this sulphation, and maximises the life and performance of your battery.
New batteries start sulphating almost immediately if they are not charged regularly. The real answer is to upgrade to a better charging system, to make the most of what you’ve got.
We’ll be looking at different battery technologies in depth in a future issue, but for the purposes of rapid battery recharging, a standard lead-acid battery is considered the best compromise. The technical folk at Sterling will tell you that specialist batteries such as gel, AGM (Absorption Glass Mat) and maintenance-free are not conducive to fast recharging.
Lead-acid batteries can be charged at a higher voltage (thereby more quickly) than the specialist ones, but doing this evaporates tiny amounts of electrolyte as it does so, which needs replacing with distilled water. Other batteries, including maintenance-free types, cannot be topped up, and therefore cannot be charged as quickly.
The above is an extract from an article published in the February 2005 issue of Practical Motorhome magazine. The full article goes on to cover:
Charging from the mains
Charging on the move
Smarter charging
Other mobile charging options
Which is best for you?
Back issues are available by phoning 08456 777812.
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