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  • Battery Technology

AGM batteries vs. gel batteries

At first sight, an AGM battery looks like a gel battery. However it has greater power and reliability.
Mechanic working under car

Gel battery or AGM battery? These are the differences

What are the differences and what do the batteries have in common? Both types of battery are VRLA batteries and are equipped with a vent valve. The abbreviation VRLA stands for Valve Regulated Lead Acid Battery. With this closed battery type the hydrogen which is generated by the battery is recombined, so that topping up with distilled water as with wet batteries is not required. Apart from these common features, there are significant differences between gel batteries and AGM batteries.

Gel batteries

A gel battery has a similar structure to a conventional wet battery. The positive and negative electrodes are surrounded by an electrolyte. However, as the name suggests, the electrolyte is not in liquid form but rather is in the form of a gel due to the addition of silica. This provides greater resistance to vibration and the inclination of the vehicle. The encapsulated design facilitates handling and improves safety. If the battery is in an intact state, the user does not need to be afraid of leaking fluid. Therefore, in the trade, gel batteries are often referred to as maintenance free batteries.

AGM batteries

The abbreviation AGM stands for Absorbent Glass Mat. In an AGM battery, the electrolyte is completely bound in a glass fiber mat. AGM batteries are leak-proof and can also deal with inclined positions without problems. This, and their resistance to vibrations are the reasons why AGM batteries are especially favored for off-road and motorcycle use. In comparison with conventional starter batteries, AGM batteries can withstand three times as many charging cycles. The increased performance which is achieved by the structural features, is one of the main arguments for the use of an AGM battery. Long life, excellent performance and greater safety make AGM batteries the premium batteries for modern vehicles.

Comparison of the characteristics of gel batteries and AGM batteries

Gel batteries score highly with their low electrode wear, which results in a longer service life in comparison with conventional lead-acid batteries. However, due to their increased internal resistance gel batteries cannot produce high cold start currents within short intervals. A second disadvantage is their susceptibility to temperature fluctuations.

AGM batteries have been specifically designed for vehicles with automatic start-stop systems and increased power demands. AGM batteries are recommended for all drivers who operate a large number of electrical devices and driver assistant features or who simply require greater starting and supply reliability through an extremely high performance battery. The positive features of AGM batteries include:

  • Leak-proofing
  • Position tolerance
  • Vibration resistance
  • Greater Safety

Even if the casing is damaged or broken, the acid remains bound in the glass mat. An uncontrolled escape of battery acid can therefore be largely ruled out.

When is it worth buying an AGM battery?

The high, constant cold start current makes an AGM battery the right choice for vehicles with start-stop technology and recovery of braking energy. Even vehicles with simple automatic start-stop systems and increased power requirements benefit from an AGM battery. The large number of charging cycles increases the service life and therefore cost-effectiveness. Conventional gel batteries are designed for use as supply batteries, but not as starter batteries and certainly not for cars with automatic start-stop systems or vehicles with a large number of electrical consumers. AGM batteries are the modern answer to the need for more dependable energy, environmental compatibility and reliability.

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Got a question?

  • Make use of our VARTA Battery Finder to find the battery product that fits your vehicle.

    GO TO BATTERY FINDER

  • According to the 2024 ADAC breakdown statistics, 44.9% of all vehicle breakdowns are caused by battery issues (see: https://www.adac.de/rund-ums-fahrzeug/unfall-schaden-panne/adac-pannenstatistik/). Ensure your battery isn’t one of them.

    Find a trusted VARTA® Partner near you and get your vehicle battery checked!

    Go to VARTA Partner Finder

  • To extend your vehicle's battery life, consider these tips:
     
    1. Charge Care: Regularly monitor and charge the battery, especially during long-term parking or winter storage. Charge every two months if used sporadically.
    2. Check Charge: Regularly check battery charge, particularly in cold weather or after short trips. Dimming headlights indicate low charge.
    3.  Prioritize Safety: Conserve battery by minimizing non-essential electrical use and keeping safety systems active during long drives.
    4.  Clean Installation: Keep the battery and terminals clean to prevent discharge and enhance charging efficiency.
    For more information find our article "Correct battery care"
     

  • Have your battery tested by a workshop before temperatures drop, especially if the vehicle is older or used mainly for short trips. Preventive testing is the most effective way to avoid battery problems in winter.

  • Start by switching off all electrical consumers and trying a jump start with proper cables or a booster pack. If you repeatedly find the battery dead in your car, it’s often a sign of internal ageing rather than a one-off discharge. In that case, have the battery professionally tested to confirm whether it needs replacing and to prevent the issue from returning in winter.

  • Cold weather slows down the chemical reactions inside the battery, reducing its available power. At the same time, the engine needs more energy to start and heated features (lights, blowers, seat heaters) increase consumption. This combination makes battery failure and other battery problems in winter much more likely.

  • Finding the battery dead in your car during winter is often the result of summer heat weakening the battery, with cold weather then reducing its remaining power. As temperatures drop, starting becomes harder and existing weakness becomes visible.

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