I hope I just got a bad unit, but this battery stopped working for me after only about two and a half months of use. There's a little light on the side of the battery that's supposed to light up only while it's on the charger. the light on mine stays on all the time. When it's in the vacuum, the machine is very erratic. Sometimes it wont start when I hold the power switch, sometimes it shuts itself off mid-use, or it starts and stops on it's own even when I'm not touching the power switch.I still have my original battery so I tested it out. The vacuum performs perfectly fine with the original battery (except it dies after about 10 minutes cuz that old battery is pretty much dead).