Bought a pair of these batteries for two robots that i own. One battery has been working like a charm. The second battery would not hold a charge. I sent it back and it was replaced very quickly. However the replacement didn't hold a charge either. I sent that one back also. They would not send me a third replacement, so I had to get a refund. I am now in the process of ordering a battery from another supplier. Hopefully that one will work.The price is right on this site, but not if the batteries are not going to work.