I've purchased products that have other battery chemistries and they still said to charge for more than eight hours. I don't know the real answer but I kind of always assumed it was just to ensure that some anxious consumer didn't jump the gun and ruin the batteries immediately. Tell people to charge something for 15 hours and even if they get impatient at 10 hours the device got it's first full charge. Tall someone to charge something for 8 hours and let them pull it at 4 then you have a battery that never reaches full potential. I'd like to know the real answer so if anyone knows it kindly step forward.Is that due to memory effect which exists just for NiCd cells?