If I understand this exactly as written, Mine do not work that way with my charger.

I have an on board charger on the boat, but I have a standalone charger that has a massive amount of setting for various batteries.

As an example when set to AGM, 12v, 15amp, 65deg, and then I select "current" it will go to 15.5 when it's near flat.

as the battery charges, the current will read lower and lower amps until it clicks to the display that says FULL.

It will not set at 3-4 amps forever. I'll say this though. When that thing is dead flat, it will charge from 15 plus amps in a couple hours to 3-4 amps, and that last 3-4 amps takes just as long as the first 10-20 amps did.

It takes a long time to get that last bit of power stuffed in there!

Oh Forgot to add, I have two of those big blue and white Sears AGM deep cycle marine batteries, they are the best batteries I've used for the boat and the trolling motor. Probably the same one you're talking about. Mine are likely 75 pounds each, I think they might be bigger then 600CCA? They are Size or class 31 batteries if that helps?

www.huntingadventures.net
Are you living your life, or just paying bills until you die?
When you hit the pearly gates I want to be there just to see the massive pile of dead 5hit at your feet. ( John Peyton)