I recently bought roomba and found out that the battery type from this refurbished unit is not the original Ni-MH or it called "yellow APS battery". It comes with Ni-CD or "black battery" which only lasts 40-50 mins operation time per charge. Roomba typically spend 20-25 min per room thus it can only clean 2 average rooms max out of this Ni-CD. The original battery Ni-MH is last upto 120 mins which is almost 3 time longer (meaning capable of cleaning 4-5 or even 6 room at one charge). This won't bother me much until I started using roomba and found out that my 3rd room never get clean since roomba will run out of power before reaching the 3rd room and next cycle it started from 1st and 2nd room again.Beside the Ni-CD battery costs $30-$40 and original Ni-MH battery costs $90 from irobot store meaning $50-$60 price difference. The brand new roomba 560 costs around $300 which is almost the same price of this refurbished unit with original yellow APS battery so I will think twice before buying another refurbished roomba. I gave 3 star for this reason.