Most of the negative reviews of this charger are because people were expecting a fully automatic "smart charger" which is unrealistic at this price. But, the good news is, if you have overnight to charge you batteries, most don't need a smart charger. This is a "trickle" charger and, while it takes longer to charge your batteries, there's little risk of leaving the batteries charging for up to several days at a such low rate (for those who don't believe this, check the battery manufacture datasheets). It also won't cause your batteries to heat up, shortening their life, like a fast charger will.