We ordered two Brompton kits at the same time, one came as expected with the new MAX battery the second arrived with a MAX battery but the rest of the kit was for the previous style battery. They did not work together. So there was a few weeks of back and forth before this was resolved. A bit frustrating. Once installed the kits work great and help flatten the hills a bit for these later 50’s riders. My biggest issue with the kit performance is that there is more drag on the motor wheel when powered off than would be ideal, it makes for slightly less enjoyable power off riding.