Absorbent glass mat (AGM) lead-acid batteries, have fiberglass mats between their sets of lead plates. This arrangement keeps their electrolyte stable, by preventing it sloshing around in liquid form. So why is this simple technology still with us, when lithium-ion batteries are lighter and more powerful? Or, if you like, why do AGM batteries start US autos, as they have for more than a hundred years?
AGM Batteries Start US Cars In the Dead of Winter
Winters seem to be getting colder across the northern hemisphere. Some say this is part of a natural cycle, while others believe we are entering a period of climate change. We can take our pick of the reasons, but two things we cannot dispute:
- Lithium-ion starter battery performance drops away under cold conditions. They operate best between 0 to 35 degrees C (32 to 95 F).
- AGM and gel lead-acid batteries keep going between -40 to +55 degrees C (-40 to 130 F), although older ones are sluggish below freezing.
So to put it simply, AGM batteries start US cars below freezing, provided we keep them charged, and they are not damaged or beyond their use-by-date.
How Low Operating Temperature Knocks Lithium-Ion
A controlled chemical reaction occurs inside every battery between its constituent materials, every time we charge and recharge it. These chemical reactions release the energy that we as users encounter as electricity.
Batteries have evolved to work best in room-temperature laboratories, because that’s where their development took place. Therefore, it was probably inevitable that their chemical reactions would slow when batteries get icy cold.
This phenomenon is the underlying reason why there are so few lithium-ion starter batteries on the market. But their winning competitors, AGM lead-acid batteries win hands down, because they are so robust that they can cope with U.S winters, and more.
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Starter Battery Warning Signs This Winter
