The iRobot 960 battery comes with a 1800mah battery. This battery is rated at 5200mah, almost 3x the capacity. HOWEVER, the 960 unit seems to know if a COUNTERFEIT battery is installed as this battery NEVER ATTAINED a full charge, but after a period of time on the charging base issued an error-5, charging error.Removed and verified the contacts were clean; re-installed; verified the charging base and unit contacts were clean; reseated on the base and within 30 minutes. error-5.This battery is being returned for Credit.Lesson learned. I guess you DON'T get what you pay for!