The stock power supply on my Max works great for me, I have no complaints about it at all! In fact...my scooter never gets to 0...whenever I ride and come home it's usually in the 70% battery range...the lowest ever was 50% and the stock charger charged it back to 100% in like 30-45mins or less....so this fast charger must be for when you're @ "0" & it'll charge it in 3hrs. I found one in stock @ Segway Europe...purchased it, but they don't ship to the USA sooooo after my refund I guess I'll have to wait until we get it back in stock here. Even tho I don't have it yet.....it's def a good accessory to have in the stash!