Batteries will discharge over time even with no draw on them. That's why people use tenders on seldom-used batteries. As batteries discharge the plates in them gather a coating of sulphates that reduces the interaction between the plates and the electrolytes. This reduces the available charge and the recharging. This reduces the service life of the battery.
In the case of the OP, though, it sounds like the battery gets used but the car is not driven enough to keep the battery at top charge. In this case, a battery tender will keep the battery at a charged state, reduce the formation of sulphates, and cause a longer service life.
Still, the charging system should be checked to ensure it is doing its job properly.
In the case of the OP, though, it sounds like the battery gets used but the car is not driven enough to keep the battery at top charge. In this case, a battery tender will keep the battery at a charged state, reduce the formation of sulphates, and cause a longer service life.
Still, the charging system should be checked to ensure it is doing its job properly.
