Final shake down: 42 mile range 15 amp Bafang BBS02

[0utrider]

I’ve finished a 42 mile trek this past Sunday on a Bafang 750 BBS02 mounted on a Mongoose XR-Pro. I'm sure I could have extended that further if the route was flatter and I pedaled more.

I got some creaking noises while cranking hard. I put blue thread lock on the bottom bracket nuts and they did not back out and the motor seems solidly attached to the frame at the end of the ride so I don’t think it’s the bottom bracket. I tightened the crank bolts to make sure they were not the fault and after testing think I think it’s the el-cheapo “spring” rear suspension that’s contributing to the noise. The headway 15amp battery being used began to really drop capacity nearing the 35 mile mark and I had to keep assist at two or below on the last few miles. Most of the trip was in assist levels 3-5 which were more than ample. I did gear down for the taller hills and it took most of the hard effort.

So, enough shake down cruises and I’m going to begin the refinement process and disassemble the battery pack in order to engineer an easily removable saddle mount with a carry handle which rests on the top tube near the head tube much like a motorcycle gas tank.

My goals have been far surpassed. I have very good range... AND SPEED!

[youtube]gZEV0kFOCzM[/youtube]

I’m considering this project a success and now just need to refine the build. I want to thank you for everyone’s past suggestions and observations. After I finish up the battery, make a few bike upgrades and some much needed wire management, I’ll be looking forward to the next project. Perhaps a beach cruiser with a hub motor or a mid-drive fat tire bike?

 

[dnmun]

looks like 16S of the 15Ah headways so about 750Wh and at 15Wh/mile it should last for 50 miles if properly balanced which that BMS will do.

wrap it up in a plastic bag to keep water out of the BMS or it will shut down when it rains.

or if you can find a small plastic box to put the BMS inside and seal it up that will be good enuff.

water on the battery itself is not too bad unless it is really heavy rain and the cells leak more current through the water on the terminals. but it will be small in any case. but the BMS will shut off if it gets wet.

 

[0utrider]

looks like 16S of the 15Ah headways so about 750Wh and at 15Wh/mile it should last for 50 miles if properly balanced which that BMS will do.

Yup. Multi-meter shows they all the cells are right where they should be. Fifty miles? Yeah, I think I could do that on flat terrain if I keep the speed under 20 and I'm in the right gear to not lug the motor with these 29" tires. For fast runs over 25 miles, I'll bring my charger to be certain I can get back.
Let’s see… 220 pounds of me, 20 pounds of junk in the backpack, 18 pound battery, motor, bike, 29er tires…. It all adds up to a heavy load.

wrap it up in a plastic bag to keep water out of the BMS or it will shut down when it rains or if you can find a small plastic box to put the BMS inside and seal it up that will be good enough.

I've been looking for a right sized box (tool boxes, Tupperware etc... ) with not much luck. If I find something that fits, it's either too tall to fit between the seat and the rack or too oddly shaped to be unwieldy. Since every trip so far has been dry weather riding, no problems with the BMS giving up the ghost. I'm just not happy with it sitting on that rack. The Thule supposedly can hold 50 pounds but it shifts and twists out of centerline slightly especially if the bike is leaning on the kickstand. Nope, it's not coming loose but I don't like having to center it every now and then. I have a design in mind to make a box that straddles the top bar four cells longitudinally and hanging six cells on each side. My first draft drawings show it looking somewhat like a gas tank for an motor bike. I'll be building a mock up in cardboard to test fit and assemble the final box out of a durable plastic sheet perhaps commercial kitchen cutting boards shaped and screwed and glued together. I plan to put ports for connecting the charger, motor and two outlets wired to a couple fo buck converters I picked up for the purpose to charge my phone and power the LED lights.

Thanks for your suggestions and comments! dnmun!