The Importance Of Smart Battery Chargers For Auxiliary Batteries

A battery is constructed of a number of cells, with a lead-acid battery cell generating around 2V. Small batteries will typically contain 6 cells in one battery container, adding together to total 12V at the terminal points. Although these batteries are referred to as 12V batteries, the voltage of a 12V battery can vary from approximately 12.6V - 10V when discharging and can rise up to 15V - 16V while charging.


Charging batteries to maximum capacity requires different stages of charging. Charging in different stages is vital in ensuring the battery is not damaged at all during the charge process. The most common, modern type of battery charger used for this purpose is often referred to as a Smart Battery Charger. Smart Battery Chargers are chargers that have a minimum of 3 charging stages with a basic smart charger starting in a boost stage, then moves into the absorption stage and finishing on either a float and/or maintenance stage of charge. We have a range of smart chargers to suit your needs.


Let's go through these stages:



This is the first stage of charge and allows the charger to put in maximum capable current into the battery for as long as it can safely do so. This stage operates as a constant current charger, meaning that if the charger is rated to 10 amps, it will charge at a constant rate of 10 amps until the battery reaches a voltage set point. The voltage set point of a battery is generally around 14.4V - 14.7V and at this stage, the battery is approximately 75-85% charged.



Once the battery reaches approximately 75-85% charge, the battery charger will automatically switch over to the absorption stage. In this stage of charging, the charger now changes into a constant voltage charger, ensuring that the voltage is held at a set point (typically around 14.4V). This is done by slowing the current (amps) rate into the battery, otherwise the voltage would continue to rise. The purpose of this is to allow the battery to adsorb the last of the required current (amps) that is needed to read fully charged.



Depending on the smart charger you are using, your battery charger may enter float / maintenance mode as early as 85% state of charge, however other battery chargers may begin closer to 95% state of charge. The float stage of charging means the voltage tapers down and maintains a steady 13.2V - 13.4V - the maximum a 12V battery can hold. During this stage, charge is constantly going into the battery, however the charge rate is adjusted to ensure a full state of charge (100%) and nothing more. This ensures you do not overcharge and damage your battery. Most smart battery chargers will not shut off at this point, however it is safe to leave a battery in float mode for months at a time. This stage of charge is also commonly referred to as a ‘trickle charge.’


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