Mon. Jul 15th, 2024
AGM Technology Batteries

AGM batteries are becoming more and more popular. Until recently, such starter batteries were found only on motorcycles and boats, and today they are under the hoods of many cars, and not only hybrid ones. AGM battery attract motorists with powerful performance, but they scare away with a high price. Is it worth it to change the good old “lead-acid” with liquid electrolyte to the newfangled AGM, or is this just another marketing? Let’s figure it out.

AGM Technology: First Of All Airplanes

In fact, the “new” AGM technology is already half a century old. In the 70s, engineers at the American Gates Rubber Company improved the classic lead-acid battery by replacing the liquid electrolyte with absorbed (i.e., absorbed, absorbed). Special porous inserts were placed between the battery plates – acid-impregnated fiberglass mats. This design gave the name of the AGM technology: Absorbent Glass Mat – an absorbent mat made of fiberglass.

Fiberglass “sponges” not only hold the electrolyte, but also act as separators between the lead plates, allowing them to be arranged more tightly. Due to this, in an AGM battery of the same size as a conventional liquid one, there are more plates, and its capacity is higher. True, the mass is larger: AGM batteries, having more lead inside, are very weighty.

The military immediately became interested in the invention, because the absence of liquid in the battery promises many advantages. The AGM battery can work in any position (at an angle, on its side), nothing flows out of it and does not even evaporate: the gases released by the electrolyte circulate inside the case without oxidizing the terminals. The AGM battery works stably at low temperatures and is very resistant to vibrations. It is not surprising that such batteries have become a real godsend for aviation, where all these factors are fully present.

Mass Use Of AGM Batteries

Motorcyclists followed behind the aviators. After all, when the motorcycle tilts, the liquid electrolyte in a classic battery strives to leak out. AGM technology has solved this problem – there is simply nothing to flow out here. In addition, AGM batteries are much safer than usual ones in case of falls: even with serious mechanical damage (literally, with a broken case), an AGM battery continues to work without shorting out or flooding everything around with acid.

AGM was also appreciated on the water: in boats and jet skis, such batteries have been used for a long time and successfully. Vibration resistance, resistance to buildup and tightness of the battery – what you need for water motorists.

AGM batteries are used on a truly massive scale in industrial and household electrical appliances, where a sealed, maintenance-free design turned out to be most welcome. In addition, AGM batteries can withstand many charge-discharge cycles and can deliver current for a long time without fear of deep discharges that are detrimental to classic batteries. Batteries of most emergency power sources are made using AGM technology: from computer “uninterruptible power supplies”, automatic gates and barriers to backup power for power plants.

AGM Batteries In Cars

Why are batteries with liquid electrolyte still working under the hoods of most cars? Of course, because of their availability. The price of a car AGM battery is about 2 times higher due to the complex production technology and expensive high purity lead. Automakers do not want to overpay and complete cars with conventional batteries that do a good job with typical tasks.

That all changed with the advent of hybrid cars, as well as the start-stop system, which turns off the engine at every stop to save fuel. At the same time, all on-board electrics (including lighting, climate control and audio system) continue to work – the load on the battery increases significantly! And here, conventional batteries can no longer cope, because they are simply not designed for such bullying.

In such difficult conditions, the advantages of an AGM battery are fully revealed. Firstly, it charges faster, managing to replenish current reserves even during short city trips. Secondly, AGM withstands 3 times more discharge-charge cycles than a conventional wet battery. Thirdly, an AGM battery is much less sensitive to deep discharges and is not as susceptible to sulfation. Therefore, AGM works great on cars with the Start-stop system: both on hybrid and classic internal combustion engines. Most hybrids (including the most popular Toyota Prius) are equipped with an AGM 12V starter battery from the factory.

However, batteries for Start-stop systems and hybrids are not only AGM, but also EFB – Enhanced Flooded Battery. These are more affordable batteries with a liquid electrolyte, adapted for frequent discharges and charges. Do not confuse them, they are different technologies. EFB is a “reinforced classic”, but they do not have the advantages of AGM.

Pros And Cons Of AGM. Is It Worth Buying?

With cars with the Start-Stop system and hybrids, everything is clear: they need an AGM battery and are “registered” from the factory. If you need to save money, you can consider a more affordable alternative – EFB, but let’s be honest, an AGM battery will be better in everything.

And as for ordinary cars – does it make sense to put an expensive AGM battery in them? To decide, we list the main pros and cons of AGM batteries:


  • High starting current
  • Faster charging
  • Frost resistant
  • Deep discharge resistant
  • Sealed and fumes free
  • Can be installed in any position
  • Long service life


  • High price
  • More weight
  • Sensitivity to overcharge