Charging questions

[TheNinj]

I've got a Mtroniks J4 peak delta charger. It has a switch that selects either 1A, 2A or 4A.

I have 4 batteries (stick packs) 2x 3600, 1x4000 and 1x4500 mAh.

I understand that you're supposed to charge your batteries at 1C which is fine for the 4000mAh battery because I can use the 4A switch.

But what about the other batteries? I've been charging them all at 4A. Is this correct? I've noticed that it takes a good few hours to charge, even the 3600's take about 2 hours at 4A.

Should I be charging them at a different rate? Shouldn't a 4000mAh take about 1 hour at 4A?

Have I been buggering up my batteries?