Dreame X40 Ultra vs iRobot Roomba j7

“I tested and retested the Dreame X40 and X30, they just didn't do as good as the older L20, I don't know why, but it was consistent over many tests. Same thing with the S8 MaxV vs the S8 Max Ultra. The short answer is that before I did this new test, I was mostly just guessing about relative differences in mopping ability, I could do the basic mopping tests that I did, but those really only helped me find particularly bad mopping robots, they didn't help us to know which one was better than another in an objective way. Now that I have a system that, at least I believe is accurate, it will change the rankings going forward. You could argue that I shouldn't weigh the mopping ability scores so heavily in the final rankings, and I may revise that in a future algo update, but for right now I think its a good system, even if it radically changes my view on which are the best robots out there right now. One thing I have found over the years is that every release of every product is different. certain little changes in manufacturing change performance metrics even with its not supposed to on paper. testing products in increasingly better ways is the only way to keep the manufacturers honest.”

“I've got a major issue with my J7+ and it's brushes at the moment - the pale-green one (the rear one, which spins in reverse) wears out far faster than the front one and once it's lost that material, the robot effectively stops picking up anything that isn't loose on the carpet. I fudged a fix for mine at the weekend by pulling the plastic rod out of the old pale green one and inserting it into the outer material for a dark green one and fitted it. The downside to that being that whenever I fit new rollers to the robot, it starts struggling to rotate them and they even affect it moving across my carpets...”