The maximum you should charge batteries is 1C.
1C for a 3000mAh battery is 3A
1C for a 4200mAh battery is 4.2A
1C for a 600mAh battery is 0.6A
Essentially divide the mAh rating by 1000 and thats the maximum amperage you should charge the battery at.
Usually anything under 1C is fine, you can sometimes go over 1C if in a hurry but its bad for the battery. If its a LiPo charging above 1C is a good way to make it explode.