Choosing the right leisure battery for you
Many cheaper batteries overstate the Amp hours (Ah). Industry testing has shown that some of these can produce significantly less than the stated figures. However, following new European legislation this will be clamped down on, forcing the low-end manufacturers to be more honest with their Ah ratings.
More expensive traction batteries are usually priced higher simply because they are better quality. The plates inside an expensive leisure battery are bigger and thicker and the separators are lined with a glass fibre mat. Deep cycling (regularly discharging most of its capacity) causes oxide to come off the grid quicker in a cheap leisure battery than a more expensive version. The higher build quality of the expensive options do make them a few kilograms heavier though.
Often cheaper caravan batteries are lead/calcium construct and this works well if you are on a site with an electric hook-up but if there is no mains a higher quality battery may be required.
These high quality options sometimes have an absorbent glass mat which soaks up any free sulphuric acid. They also combat something called shedding which is the process by which, after a few cycles, adhesion between the active ingredient (lead/calcium or lead/antimony) and the grid is lost, potentially causing a short circuit as the mass drops to the bottom of the battery.
High quality leisure batteries can be quite expensive but if your cheaper batteries are going to have short lives and require frequent replacing, they could prove a good investment.
Be careful to look out for bulges in leisure batteries. If a battery develops a bulge it is likely caused by sulphation. If the battery is left for a while without charging, a layer of hard, white sulphate forms on the plates. If this occurs you should replace the battery, disposing of it responsibly.
Charging your leisure battery is important. Regular charging before the capacity drops below 50% will extend the life of your battery. The ideal maximum charge for leisure batteries is 14.4V but this is above the standard caravan charger which operates at around 13.8V. You can buy chargers which will charge your caravan battery to a higher level for a set period of time before dropping to a lower level to supply an appropriate voltage to the rest of the caravan.