I've never had problems with motorcycle batteries dying too soon, and I suspect that the theory that V-Twin speaks of is myth. My experience has been that batteries go for a specific reason. Mostly they sulphate up because of the constant chemical reaction going on inside. A sulphated battery goes nowhere.
Some places used to sell 'recon' batteries. They would hit the battery with a short burst of 240 volts and this would shock the plates and the sulphate burn off and sink to the bottom. It was exposed as a scam years ago as it also damages the battery but there might be people around who still do it. Leaving a lead acid battery for long periods will reduce it's life as they need to charge/recharge. My other bike, the battery lasted six years - then my wife got ill with cancer and I stopped riding until some time after she died. The battery was gone by the time I got back on the bike after ten months sitting in the shed. I replaced it with a LiPo battery, and the kick that thing has is extraordinary. The LiPo battery also lasts longer without charging, as in towards a year and it's going to be still OK. The OP who's battery lasted 18 months sounds like a faulty battery from the start. And obviously faulty for Daza with the battery gone in weeks. Most chargers sold these days will monitor battery charge and can be safely left connected.
From Woodrising (no, nobody else has heard of it either) Rides a Springfield Dark Horse