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How do I charge my AGM battery?

Correct charging makes the difference, although the influence is often underestimated, selecting the right charger is half the joy. Choosing the wrong charger can cause direct or indirect damage to the battery and shorten its lifetime. pbq has over 10+ years of experience in valve regulated lead-acid batteries. We often see that there is no good match between the lead-acid battery charger and the battery, having a negative influence on the performance of the battery and its life time. In order to choose the right charger for your battery, it is important to understand the characteristics of an AGM battery.

Characteristics of AGM batteries

The charge current for any battery is limited. For a VRLA battery, the maximum charge current is 0.3CA, meaning 0.3 times the capacity of the battery. Exceeding this threshold may heat up the battery. The internal structure of the battery and the chemistry will get damaged and the battery loses capacity permanently. The charge voltage is a different figure to pay attention to. Each cell of a AGM battery has a nominal voltage of 2V. A 12V AGM battery consists of 6 cells, connected in series.
And finally, temperature has a major influence on the performance of a battery. The charge voltage must be compensated if the environmental temperature deviates from 25ºC.

Charging 2V batteries

Charging a battery with 2V per cell will never result in a full battery. Decent charging requires approximately 2.4V. However, electrolysis of water, which is a component of the electrolyte, takes place at 2.3V per cell. Therefore it is important not to leave the battery charger on a high voltage when the battery is getting full.

Charging Gel batteries

Gel batteries have a lower charge voltage than AGM batteries (Absorbing Glass Material). Batteries used for standby applications have a lower charge voltage than batteries for cyclic applications. Always consult the information on the label of the battery and the related datasheet.

Charging regime of batteries

There are many ways to charge a battery. Every chemistry has its own specific charging regime. Therefore it is necessary to choose a VRLA battery charger for a VRLA battery. A wrong charger can damage the battery and in some cases even itself. A VRLA battery is charged following the CC/CV charging regime. CC/CV stands for the two main charging phases; constant current and constant voltage. After these two stages, you can top the battery with a trickle charge. Each stage has its own specific values adjusted to the type, capacity and the use of the battery.

Consideration which battery charger to choose

With the knowledge above it is obvious that a well-considered choice of your battery charger will extend the lifetime of your battery. You can find a lot of information regarding charging on the datasheet of your battery. Explore our large range of battery chargers!