The Bafang BPM II is back on duty

I’m not very kind to my hub motors and the Bafang BPM II bite the dust just short of 4000km. After about 3500km the one way clutch started slipping temporary and later locked-up completely. Most of the time the BPM II ran in a 24″ rim powered by a 35A KU123 controller and 15s LiPo battery at up to 1500W a little over its rated power.

To make things worst I took the trike with me to Munich last winter and had to park it outside the guesthouse for two month only protected by a canvas. While I never had as much fun commuting in winter through up to 20cm of fresh snow, salt and moisture probably took its toll on the ball bearings and one-way clutch.
A 80 ml ATF filling cured the locked-up clutch for a while but a few days later I flipped the trike on my way home and ripped off the motor wires. The next day the hot rodded Bafang SWXH went back into the Sprint.

After opening the BPM I found the Nylon planetary gears in like new condition despite flogging the hub motor at trice its rated power through deep snow and up some real hills in Bavaria. Apart from the broken clutch the ball bearings needed replacement. The rim got nicked one morning when I missed a curbstone in the snow as well. (Fixed a flat at 5AM in a mild snow storm, yet? Not nice.)
After delacing the rim and ordering a new one-way clutch complete with Nylon planetary gears here the hub went in a box and a search for a nice wide rim started at Ebay. Several month went by but a couple of days ago I finally ordered the missing ball bearings, reassembled the motor and relaced it into a 35mm wide 26″ Bellacoola downhill rim yesterday.

Today the BPM II went back on duty in the Sprint. This time lubricated with only 30ml AFT. Its pretty quiet compared to the steel geared SWXH, top speed is 2-3 km/h lower but the BPM has more torque. At first e the motor drew nearly 5.5A free wheeling at full speed but after a 10km test run around the block the new gears seem to settle-in and power draw went down to 2.15A.

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