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12V Batteries Explained

If you want to use solar power and/or wind power for an off-grid lighting or power application, you will require a battery to store the power that you collect. Most often 12V batteries are used (sometimes in series to increase voltage to 24V), and it's important to use the correct type for your application.

2 x 160Ah 12V Gel batteries
in one of our solar lighting installations

Battery Type

There are 3 basic types of 12V battery that we will consider here : Starting Batteries (often referred to simply as car batteries), 12V Leisure Batteries (also known as caravan batteries, domestic batteries and electric fencing batteries) and 12V Deep Cycle Batteries.

12V Car Batteries

12V starting batteries are used in vehicles to turn the starter motor to start the engine. Obviously, these batteries also power your vehicle's electrical items such as engine electrics, lights, instruments, radio etc however, once the engine is running the load is quite low and the battery is kept continually topped up by the engine's alternator.

These batteries are therefore designed predominantly to cope with short bursts of very high load during engine starting. They are not intended to be repeatedly discharged to a low level and when subjected to this kind of use tend not to perform well and quickly reach the end of their lifespan. Although they are relatively inexpensive to buy, they are not well suited to use as solar/wind power batteries and we do not recommend them for this.

Leisure Batteries

12V leisure batteries are predominantly used in caravans, camper vans and boats etc and are used to provide a general power source usually for 12V lights and appliances. These batteries are designed to cope with relatively long use of low loads, and can be repeatedly discharged to quite a low level.

In other words they are designed specifically for regular discharging and recharging. This characteristic, their relatively low cost and ready availability makes them ideal for small scale, non critical off-grid solar and wind power systems.

Some of our lighting kits (such as the SolarMate lighting kits) require you to supply a battery for them to work and in most cases a standard leisure battery is perfectly adequate and the most cost effective option. Leisure batteries can be purchased at most motor factors, electric fencing suppliers and car/caravan accessory shops.

Deep Cycle Batteries

Leisure batteries are a type of deep cycle battery, as they are designed for repeated deep discharge. However, a true deep cycle battery is designed for heavier duty than a leisure battery and these are widely used to power electric vehicles such as golf carts and warehouse vehicles as well as being the most reliabel battery for off grid power systems.

There are 2 main types of deep cycle battery :

1. Absorbed Glass Matt (AGM) Deep Cycle Batteries

Where we need quality and reliability at a reasonable price we tend to specify deep cycle absorbed glass matt batteries. These batteries are designed for repeated deep disharge and are ideal for solar and wind power applications.

They are maintenance free and as a rough guide we would expect them to have a lifespan of around 5+ years (depending on usage patterns).

We supply a full range of 12V AGM batteries - please contact us for details.

2. Gel Deep Cycle Batteries

In critical off grid applications (such as telecommunications and dwellings) we will usually specify a good quality deep cycle gel battery.

Due to their excellent performance and lengevity we increasingly specify and supply gel deep cycle batteries for our larger solar and wind powered off grid lighting systems.

Like the AGM batteries these are designed for repeated deep discharge and are maintenance free. We would expect a lifespan of around 8 years + (depending on usage patterns).

We supply a full range of 12V Gel batteries - please contact us for details.