Earlier this week, while attending the AMRA/MAP Technical Committee meeting, I participated in a presentation on Absorbent Glass Mat (AGM) batteries. I understand that many original equipment manufacturers are installing Sealed Agm Battery as original equipment. Although they provide many benefits (especially for car owners), they also present inherent dangers to technicians.

　　Sealed AGM Battery is sealed and non-spillable, which means that they can be installed in non-traditional locations (that is, not under the hood) and non-traditional angles (that is, not always completely horizontal). They are vibration resistant, so in addition to finding them in vehicles, they can also be found in certain motorcycles, ATVs, and many marine applications (note; do not confuse AGM with gel batteries, the latter is different). Therefore, if AGM does not have the leakage hazard of traditional lead-acid batteries, what is the hazard?

　　Because they are sealed devices, AGMs are inherently susceptible to overcharging. Traditional lead-acid battery chargers usually have an output of 16 to 18 volts-much higher than the 14.4-volt maximum specified by the AGM design. So, what is the worst-case here?

　　Using conventional battery chargers on AGM batteries may severely damage the electrolyte and cause premature battery damage. Traditional chargers may also cause AGM batteries to explode, which is a danger we never (forever) want to expose to technicians.

　　Traditional lead-acid batteries and these new AGM batteries are usually very similar in appearance. Before connecting a regular charger to the battery in the vehicle (especially if it is located away from the engine compartment), check to see if it is marked with a "non-spillable" label. If so, please use only chargers designed for AGM (and/or Sealed Deep Cycle Battery) batteries.