Basics - what is a battery?

An electric battery is an electrochemical component, featuring positive and negative electrodes composed of dissimilar metals immersed in an electrolyte (acid). This assembly is housed in a case that is either sealed or fitted with a filler cap and a vent.

Basics - what is a battery for?

The battery plays a key role in storing electrical energy. Current produced by that faithful ally - the alternator, is stored & then ready to be used to start the engine and to supply various accessories such as electric windows, radio, air conditioning, door locks, etc.

Technical details


The capacity of a battery is expressed in ampere hours (Ah).  This represents the quantity of current that it can supply during a set number of hours, at a certain temperature. This nominal capacity varies in relation to the operating temperature of the battery.

State of charge:

It is not easy to determine the state of charge of a battery. It is best to test it regularly. A lead acid battery should always be kept charged. Don't rely on the on-board alternator to fully charge a discharged battery.

How does a battery get recharged?

A battery does not recharge itself when the engine is stopped, except of course when using an external charger. A battery discharges itself during a long period of non-use.

Except when using an external charger, a car must be driven so that the battery can recharge itself. The required current is produced by the alternator, which, thanks to a system of belts, can only operate when the engine is running. Think of it as a kind of mini-power plant producing current to recharge the battery.

When your 4x4 is not being used the battery will gradually discharge itself. Certain components continue to drain energy even when the car is stopped (radio memory, clock, etc ...). Cold weather combined with a long period of non-use can result in a completely discharged battery.

Small journeys, like those around town, require more starts and do not allow the battery to get sufficiently recharged. In the long run, its lifespan may be reduced.

Our battery chargers:

CTEK charger

Jump starter power pack

End of the road...

A lead-acid battery wears out over time. - even if you don’t use it. A battery is considered to be out of service when it has lost 20% of its nominal capacity. A battery is at the end of its life long before being unable to start the engine.

Gel batteries

Here at Euro4x4parts we have chosen to offer one of the most reputable brands of gel batteries - Optima 

Gel battery technology is based on electrolyte frozen by the addition of silica gel. In some batteries, phosphoric acid is added to improve the lifespan of deep cycling. The battery case itself is sealed and completely waterproof. Optima AGM batteries offer particularly high performance, excellent resistance to shocks and vibration and provide starting currents far superior to all other lead-acid batteries of similar capacity.

What is an AGM battery?

AGM stands for "Absorbed Glass Mat". The electrolyte, including 70% water and 30% acid, found in a sealed AGM battery is absorbed or stabilized inside the fiberglass mats - like in sponge.

3 different models:

Optima yellow top batteries offer good deep-cycling performance. They can serve both as a starter battery or as an auxiliary power source (on-board refrigerator, etc.). They have a very good resistance to shocks, vibrations, and are of course waterproof.

Optima red top batteries are starter batteries designed for extreme conditions: low or high temperatures, vibrations. They offer the high current required for faster starting.

Optima blue top batteries are design for marine applications. They can be used both as a dual purpose starter and service battery.

Optima batteries from Euro4x4parts - a few examples:

Browse for the right battery for you and your 4x4 :

Batteries & accessories

Please note: Euro4x4parts publishes this information for the benefit of clients but cannot be held responsible for any use or misuse of this advice.

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Please note: Euro4x4parts publishes this information to help its customers, but cannot be held responsible for the advice given here and their consequences when used.