Batteries self discharge every month by themselves, hooked up or not.
You MUST keep them on a maintainer or charge them every month to keep them from an early death.
We carry a variety of chargers for a variety of applications with these being only a few examples of what we stock.
Not all battery chargers are created equal, today's multi stage chargers do a much better job than the basic ones used to.
Call or come down to Century Batteries in Abbotsford or Port Coquitlam and ask us about the best charger for your needs.