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AGM battery replacement

Given that AGM batteries are completely different to conventional lead acid battery types, it is imperative that technicians understand how to care for their wellbeing, says Banner Batteries. They have very different discharge and recharge properties to a conventional flooded lead acid or EFB type battery – fully recharging in approximately three hours due to the high plate surface area and low internal resistance.

There is no excess acid in a reservoir above the plates so they must be recharged with care using the correct equipment. A smart or intelligent charger is recommended, although a constant potential charger (variable current/constant voltage), or a modified constant potential charger (variable current and voltage) can be used. A constant current charger should never be used. This causes a build-up of excessive internal heat, causing the electrolyte to boil off and vaporise, creating pressure inside each cell. This results in a loss of electrolyte and the battery will dry out.

Vehicle application dangers

Also important, and for fear of stating the obvious, is that for a vehicle specified with an AGM/EFB type battery, then this is the only solution fit for purpose. Incorrect application of a conventional flooded lead acid battery in place of an EFB, or a conventional flooded lead acid battery/EFB in place of an AGM, will result in premature battery failure.

Correct configuration

New technology Micro-Hybrid vehicles equipped with emission control systems may require configuration to the active energy management system, which serves to control charging to ensure optimum battery performance and Micro-Hybrid system functionality.

Active energy management is a system designed to adapt the vehicles charging strategy based on battery status, the aim being to increase the availability of the Start/Stop system with the detailed data evaluation of the battery. Such a system uses information from a battery monitoring sensor located on the negative pole to measure the physical battery variables of: Temperature, Voltage and Charging current.

Given that a replacement battery has different charging requirements to a battery that has reached the end of its serviceable life, the active energy management system must be reset when the battery is replaced to prevent the use of an incorrect charging strategy. If not, this could result in loss of Micro-Hybrid system functionality, increased CO2 emissions and fuel consumption, plus loss of vehicle system functionality.

As in all walks of life, change is far easier to embrace for those receptive to learning and understanding. Knowledge will always dispel fear, and the field of developing battery and power technology is no exception. So, here’s to taking change of the future!


About Autotechnician
Autotechnician is a magazine published nine times a year, delivering essential information to independent garage owners and technicians in the UK. Delivered both digitally and in print, autotechnician provides readers with technical, training, business advice, product and news, allowing our readers to keep up to date with information they need to run and work within a modern workshop.
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