Unbelievably quick. Use the right batteries! I was going through AA batteries at an alarming rate to power a LED motion sensing emergency/night light in my garage. The 2,650 mAh batteries provide good life between charges and very good power output. But the best thing is that when they go down, the charger brings them back to life in very short order. One of my best buys! I am using rechargeables for just about anything that requires AA and AAA cells.