AGM batteries have two main types of construction: with flat inner blocks (most of them) and with spiral stacking of plates and mats. The first outwardly do not differ from classic batteries – they are issued only by the AGM marking and increased weight. Spiral AGM batteries are popular in America, although they are also represented on the Russian market – they are often put on prepared SUVs with powerful winches. Moreover, in everyday life they are mistakenly called gel, although there is no gel in them: these are ordinary AGM batteries, but with spiral blocks in the form of cylinders. There is no particular difference between “flat” and “coiled” AGM battery, they are just different form factors.
The reason for the confusion is clear: “gel battery” is a convenient term for a battery without a liquid electrolyte inside. And no one wants to go into the design features and memorize incomprehensible abbreviations.
Real gel (Gel Cell or simply GEL) batteries are made using a different technology: they use a solid electrolyte – a frozen mixture of acid and silica gel. Gel lead-acid batteries are usually used as traction batteries in industry and on various special equipment, and very rarely as starter batteries – sometimes they can be found on motorcycles and scooters.
Both AGM and gel batteries are in the VRLA: Valve-Regulated Lead-Acid Battery class. They are united by the tightness of the case (all gases remain inside) and the presence of an emergency pressure relief valve in case of strong overcharging. Otherwise, the designs of AGM and GEL batteries are different, but this does not prevent them from being confused: most starter batteries, which motorists call gel, turn out to be AGM.
How To Charge An AGM Battery
AGM batteries are charged with stationary chargers. Most digital chargers have a separate AGM charging mode, which is worth choosing – note: it’s AGM, not GEL!
A feature of AGM batteries is their increased sensitivity to overcharging. Therefore, when using an analog charger, the maximum voltage should not exceed 14.1–14.4 V. The current strength is selected as standard – 10% of the battery capacity. On some batteries, the charging parameters are indicated directly on the case – in this case, just follow these recommendations to charge the AGM safely.
Buying an AGM battery is worth it if the capabilities of a regular battery are not enough. For example, an AGM battery performs well in cold weather, delivering 30% more starting current than a wet battery of the same size – a good help when starting in winter in harsh climates. The service life of an AGM battery is about 10 years, which is 2-3 times longer than standard indicators. And if the car has powerful energy consumers (an autonomous heater, additional light, an electric winch, an advanced audio system), then installing an AGM battery definitely makes sense.
Among the shortcomings of AGM, in addition to the high price, it is worth noting only the sensitivity to overcharging – but with a working car charging system, this feature will not cause any problems.