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  • Writer's pictureTeam Vebo

AGM Batteries. Why is it so expensive?

Updated: May 16, 2019

You may had seen some advertisement or had been quoted to replace your Absorbed Glass Mat (AGM) batteries with a battery price that is way higher than your regular flooded battery. Why is that so? Before we answer this question, let’s take a look at the technology behind AGM batteries.

Unlike flooded batteries, AGM batteries hold electrolyte in a glass fiber mat to increase the surface area. The thick AGM separator absorbs and holds acid to prevent spilling. By having the electrolyte to be suspended in close proximity with the plates active material, the AGM batteries have a much higher discharge and recharge efficiency compared to regular flooded batteries.

Modern BMW & Mini uses AGM batteries.

While AGM batteries have a much longer service life(as much as 7 years in Malaysia), it is important that the battery to be charged and discharged properly. Deep cycle AGM batteries generally needs to retain 50% of its charge before the next cycle to ensure longevity. Have your mechanic check the condition of your battery and electronic system the next time you service your car.

At Vebo Auto Service, we typically use 2 methods to check the AGM batteries. The first method is by plugging in our computer into your OBDII port and stream the battery data directly from your car. If the voltage is below 12.5v, it is a good indicator than your battery may be weak.

Your car's existing sensors can tell our computer if the battery is working properly

The second method is by using an industrial grade battery tester. The tester is clamped directly to the battery and a reading would be taken. The battery tester would indicate the current state of charge, battery health and general recommendation to change the battery, if required. The tester can also perform other tests like cranking test.

The State Of Health(SOH) and State Of Charge(SOC) of this battery is still good.

This battery has a low state of health due to its high resistance value(more than 8). A brand new battery will register a value of 3mΩ.

One very important step when installing an AGM battery is the workshop must have the capability to register and perform coding for the new battery. Here's what the coding does:

  • Reset Stored battery statistics (battery charge level, current, voltage, temperature) .

  • Battery capacity is set to 80%.

  • Current Odometer reading is stored along with readings of previous battery replacements.

To answer the question posted earlier, AGM battery’s price is justified as it offers a far superior service life and charging/ discharging speed over regular flooded batteries. It is important for our readers to ensure that the workshop you go to checks the state of health of your batteries when you service your car. We do not want you to be left stranded, unable to start your car because your battery died. Happy Driving!

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