My Lifeline 4D AGM is coming up on its 8th season. Each year it sits, untouched no trickle charge, from November to April. This winter past it will be November to July, disconnected & no maintenance. Will see how it is in 2018 but would not be surprised if is still going strong then.
AGMs are not cheap but the zero maintenance & long service life more than make up for the price difference IMO.