My Kinetik 1400 is 8 years old and it has been the primary (starting) battery of my truck since I put it in 8 years ago. Still works and tests fine. Key point with any battery in an audio system is keeping it charged. All AGM batteries are lead acid ALL lead acid batteries sulfate when they discharge and as sulfation ages it becomes harder to recharge especially for an alternator. Leave a battery in a low state (yes even though it can still start your car) you can lose large portions of performance rather quickly (days weeks months) due to engine heat and what it does to sulfated lead. Ever see a corroded battery under the hood of a car that doesn't even have a system? That is a by product of trying to allow a low or sulfated battery to be charged with an alternator rather than a good charger. Low and sulfated batteries charge does not come up fast enough for an alternator to charge correctly without getting the battery hot and if it is already under the hood it could already be a hot battery to begin with.