As winter is now on its way, although it is quite mild at the moment, batteries become an important part of the automotive parts trade as more fail and are replaced in the winter than any other time of the year.
This is also the point in the year that a little time can go a long way in extending the life of your battery for many of your seasonal hobbies such as boat and marine batteries, motorhome and caravan batteries, jetski and motorcycle batteries as well as sports or hobby cars that are tucked away for the winter.
The first rule of maintaning your seasonal use battery is invest in a good multistage intelligent charger, this will pay you back many times over if used correctly to maintain and charge your batteries over the years. The charger should be of an appropriate size and suitable for the appropriate type of battery. A rule of thumb for chargers has always been that you would select a charger of about 10% of the Ah capacity of the battery, however this can safely be 20% or more depending on the charger and battery type. So check what the charger and battery manufacturer recommend. Many old style chargers are now unsuitable for modern batteries.
Remember that some onboard chargers on caravans, motorhomes etc do not reach the required voltage to give a modern leisure battery a good full charge, so if you are unsure, don't rely on them with a mains hook-up during the off season. Use a good quality intelligent charger.
If possible remove the battery or batteries from your application and place them where they can be charged safely.
If you are unable or it is very troublesome to remove the battery some chargers have hard wire kits available that allows for only a small simple plug to be used once wire on to the battery.
Check the physical appearence of the battery to ensure there is no damage to it, and if you are able to, check the electrolyte level inside. Many modern batteries are now sealed and do not allow you to open them.
Now simply place the battery on charge. Remeber to do it in a ventilated area as all batteries have the potential to release gases which under very rare conditions can be explosive if not ventilated well.
If the charger has a recondition function then it will probably be good to let the charger run this cycle once if your battery is a few years old and the vehicle it is on is hardly used. Normally this takes the battery up to or above 15V for a short period of time allowing acid to circulate and possibly breaking down some mild sulphation.
Many smart chargers are able to be left on indefinitely as they drop to a float voltage which is designed to maintain the battery and not damage it. Although I tend to leave it fully charged for a few days, then disconnect the charger. Then place it back on charge once a month for a few days or over a weekend.
A simple battery maintenance regime with a good charger can mean a battery used for your hobby will last many years as opposed to having replace it every year or two.