I constantly have a red LED that flashes meaning that there is a problem, and this with ALL the batteries I tested. So, my batteries recharged never ... and I lost a lot a lot of time trying to find a solution by changing the place of batteries in the charger, changing electrical outlet, or by going to forums but nothing works. In short, too much time is wasted just for piles..maintenant I'll just buy normal alkaline batteries and charger will head ............. trash !!!