These ARE very good battries!!! I have 6 of these and they work great. There a little big for my HBK2 but a small amount of lead solves that. When I'm just doing hoovering excercises in hte basement I'm gettin about 12 -15 min. I do think that I run them a little long but they still charge back up and never get too hot. I am going to start checking volts as soon as I figure a easy way for me to do it.
Since were talkin bout this whats a good batt. checker? You know one with a light to mount on the bird.
PS the batts are on backorder right now so get your order in for the next shipment.