Lead acid batteries, of which AGM is a variety, can have electrolyte freeze when their state of charge drops too low. A fully charged lead acid battery will require extremely cold temperatures (I want to say -65 or colder) to freeze, while a fully depleted battery may freeze around 30F.

AGM still has the liquid electrolyte, still has the acid, its just absorbed in a matt. That doesnt change the freezing point. The good news is that AGM tend to self-discharge less...

If youre keeping it on a charger, youre well ahead of the game. The small amount of dissipated energy in a float charge can create some heat, and it keeps the electrolyte in a concentration that is freeze resistant.

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