Batteries and Chargers
Lead-acid batteries are the accepted standard for energy storage systems, and they are straight-forward to use under normal conditions. However, not all lead-acid batteries are the same and some are more suited to a particular application than others.
Lead-acid batteries are distinguished mainly by plate construction and in the way the electrolyte is managed, and generally fall into one of three main categories:
those which hold the electrolyte captive (gelled or Absorbed Glass Mat (AGM) types);
those which limit electrolyte loss (sealed vent â€™maintenance freeâ€™ types);
and those that allow refill of lost electrolyte (open vented types with refill caps like Starting, Lighting and Ignition (SLI) or Traction batteries).
For 4×4 and leisure use most batteries fall into the maintenance free category. These are available in 3 types:
Cranking or starting: used for engine starting, made for high current draw for a short period, typically should not be discharged more than about 10%, i.e. donâ€™t go below 90% state of charge.
Often referred to a sealed maintenance free batteries, these do in fact have a small vent, which can allow gas to escape. The battery should always be kept upright, as it will leak electrolyte (Acid) if left on itâ€™s side or upside down for more than a few seconds. Care should therefore be taken to mount the battery in a spill proof container to contain any acid which may escape. These batteries should never be opened, and it is not possible to top up the electrolyte (Acid).
Deep cycle: used for auxiliary equipment (fridges, lights, etc), made for low current draw over a long period, typically should not be discharged more than about 50%, i.e. donâ€™t go below 50% state of charge.
High cycle: used for standby (ups), typically should not be discharged more than about 25%, i.e. donâ€™t go below 75% state of charge. However certain brands have high cranking ability and can easily be used in place of a cranking battery. Because they can also handle discharging better than a cranking battery this is a good option to also run some auxiliary equipment to relieve the load on the deep cycle battery.
To maximize battery life, the correct battery should be chosen.