g'day,
as with charging batteries, it is ideal to charge a Sealed battery to approximately 10% of it's capacity and not to give it too much current. Too muhc current, and being sealed may cause the plates to pop, because there is no exhaust for the gasses to escape which is a concern for ANY BATTERY BEING CHARGED!
As stated, if you have a 100amp battery, then 10amp charge would be great.
With a 6 Stage charger, it is exactly that, it will pump it's total capacity [charger dependent], and then in 6 stages when the battery is getting close to full, switch to trickle.
If you can, get a charger that is close to 10% of the batteries capacity.The battery will last longer because there is no sulpheration build up that can occur when you are only 'topping' up the battery.
As most poeple know, just make sure that your charger does switch to to a trickle cause you don't want that hundred dollar battery being useless in the first season.
ta,
pete:)