Updated 10/31/2020: After only a few months of use and less than ten charges, the battery is able to carry a large charge. I get more run time from the original one I replaced. I think you pay for what you get. You might not even get what you pay for in this case. Updated 09/10/2020: Did the same test with a 3Ah iRobot battery (from my friend's Rumba that is a few years old) and about 2.5Ah (38W from full charge to 10V) obtain. So the original Roomba battery is not bad, even if it is several years old. Original review 9/8/2020: I ordered this for my Roomba 650 and it runs for about 40 minutes before needing a charge. I'm an electronics engineer and have worked a lot with batteries and circuits, so I have a rig to test battery capacity. I started the test after the battery was fully charged (about 16.8V) by pulling a 1A DC load and reading the wattmeter. When the voltage dropped to around 10 volts it came out around 21 watts so the actual capacity is around 1.5Ah, a far cry from the advertised 4.5Ah. I suspect that most batteries sold in this price range overestimate the capacity. Since the area that I have to clear is not that big, I leave the battery where it is, as it can at least do its job when fully charged.
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