Trickle charging batteries outside in the winter? : r/batteries
If you are worrie hat much, remove it from the mower, take it into the garage for the winter, throw the charger on it once in a while. I left my mower outside all winter, gave it a top up charge early spring (2A until the charger was needed elsewhere), seems to work okay now, after sitting a couple months, for an older battery (5+ years old).
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