http://www.campingandcaravanningclub.co.uk/Documents/Looking%20after%20your%20leisure%20battery.pdf" onclick="window.open(this.href);return false;
"What is the best way to charge a battery?
What's needed is a staged charger that senses the state of charge of the battery and supplies the voltage that best suits that condition. There are several models from which to choose, ranging from a decent two-stage charger at around £80, to complex multi-stage chargers that use state-of-the-art circuitry to ensure optimum performance of the charger and battery, but these can cost hundreds of pounds.
A two-stage charger will sense the battery's state and, if its charge level is above a pre-set level it will supply the 'normal', or 'float', charge of 13.8V. But if it detects that the battery charge level is below the pre-set level, or is fully discharged, it will start charging with a 'kick-start' at over 14V and automatically switch back to 13.8V once it has detected the battery charge has risen out of the danger-zone. This initial boost prevents the build up of sulphate deposits. Overall, it takes four to six hours for the battery to hold a credible charge.
The root of the problem is money. Caravan manufacturers, who strive to keep production costs down, fit a 'charger' that does the job for the least cost. (Dealers then fit the batteries.) But, with a decent 110Ah leisure battery now costing well over £100, spending a few extra quid on a better charger is a good idea. Once your battery fails, most battery retailers will take another £100 off you without exploring or explaining the cause. However, change normally only comes in response to consumer pressure and certain makers are looking at improvements in this area.
For the time being, the only option for most of us is to change the existing constant-voltage charger for a newer, staged charger. Several are on the market, costing from around £80, and they're relatively easy to fit (see p137). If you're not competent with electrics, your dealer will fit it for £30-£50. "
:mrgreen: