Absorbed Glass Mat (AGM) batteries have been installed in vehicles since the 1990s and are being used in approximately 40 million vehicles in North America, growing at a rate of around 8 million batteries per year. They are found in some application of virtually all original equipment manufacturer (OEM) fleets today, including (but not limited to) high voltage hybrid and battery electric vehicles (BEVs). They are also commonly found in vehicles that employ stop/start technology.

These batteries typically provide higher cranking power and reserve capacity than flooded lead acid (FLA) batteries of the same group size due to the larger plates (no need for space for free flowing electrolyte and a sediment chamber like FLAs) and — here’s the identifier — they are labeled as non-spillable.

Their highly compressed design and higher density material provides better vibration tolerance and a substantially longer life than their FLA counterparts (as a result, they are typically more expensive to purchase).

AGMs are often found in non-traditional locations (such as in the trunk of the vehicle) and – because they are non-spillable — they may be mounted at what many would consider unusual angles.

So, what are the safety concerns? Because they are manufactured as sealed units, they are vulnerable to being overcharged. Conventional battery chargers oftentimes have outputs of 16v to 18v; AGM’s should not be charged above 14.4v. Conventional chargers can cause severe damage to an AGM which could lead to the battery exploding.

AGM Best Practices:

  • Assume that every battery you service/replace is an AGM.
  • Use smart chargers whenever servicing an AGM battery that is low on a charge.
  • Never downgrade the vehicle to an FLA if the OEM equipped it with an AGM.
  • Always wear the appropriate Personal Protective Equipment (PPE) when working on or around batteries.

Want to learn more? CCAR offers a complimentary online AGM Battery Safety course. Simply go to www.ccar.training to sign up and take the course. A final exam is offered which provides a (printable) Certificate of Completion upon successful passing of the exam.


About CCAR: The Coordinating Committee for Automotive Repair (CCAR) is a non-profit organization with a focus on the automotive industry and its needs for safety and hazardous material compliance and training. Founded in 1994 with grant funding from the Environmental Protection Agency (EPA), CCAR is also one of the original Occupational Safety & Health Administration (OSHA) Alliance partners and is the only OSHA Ambassador focused on providing safety best practice information to the automotive collision and repair industries. CCAR has twice been recognized by the ASE Training Managers Council (ATMC) with their “National Excellence in Training” award and was chosen by the North American Hazmat Action Committee (NAAHAC) to develop hazardous material-handling training courses. To learn more about CCAR and its programs, please call 888.476.5465 or visit www.ccar-greenlink.org.