RobAV

Not voltage sag, it's the controller thinking your cruising when in PAS ( different in throttle mode, that's user on demand), mines a 17.5ah Samsung bat and drops about 2v when maxed (then rises when backed off) . Same problem here a 40t is great for hills (but slow), a 44t is a good medium (I have both), but a 50t or more would be great for flatter terrain cycling. .the problem is the lack of torque from the BBS01B, raising the chainring size will put undue heat into the motor on inclines, drawing loads of amps but unable to accelerate or maintain a constant, so producing excess heat...and then something will break/ burn out.

On the display, it's not running out of cadence (approx 80-85rpm) it's the controllers presuming your cruising so dropping the watts ( amps in reality) as it's not detecting your accelerating, so it gives enough power to maintain the speed it THINKS you need. By the way, at 15amp 80% keep current is only a max of 12amp (40v x 12a = 480w...so many people get this setting wrong, they read those old US threads, keep current is a safeguard setting related to to the Limit Current setting on the Basic tab...it's this setting that all the PAS levels read from, not the Limit Current setting. Limit Current is the max allowed into the windings, Keep Current is the percentage of that current to use, the PAS levels are values of Keep Current. HTH.

I had my 01B set at 18amp and 100%/100% PAS level 9 and 100% keep current for a max of 720w at 40v (42v fully charged minus 2v bat sag) ...good but just as you said above still slow uphill, although fully capable of climbing its sub 10mph up steep gradients of 12% plus. On flatish ground, woohoo, the 01b flies when I lift the legal limit when away from the main roads. The prob with the Bafang controllers if using PAS (which I do) is if you're not accelerating (like going up a steep incline), it presumes your cruising and drops the wattage......

It lives! I received a refund last Saturday (from eBay) and ordered another Bbs02b from the same supplier (treek-motor) on Wednesday (I made sure I actually had the money in PayPal) and it arrived yesterday.l No problems with the new BBS, and I must congratulate eBay and treek- motor for their no cost return and 3 day refund policy, worth its weight in gold! I asked them to just swap it, but you have to get the refund first then re-order. Anyway, as I said this one works great, the jump in torque from my BBS01b is like night and day, I was smiling like a Cheshire cat riding this on a local private lane. I've not installed the throttle, as I don't use them (get a moped if you're a throttle guy IMO) and not too bothered about speed, it's hills or valleys off-road here in Derbyshire and thats where the extra torque is really felt. Must ask about our rubbish UK laws, my BBS01B is great for town or flattish riding and I'll still be using it but the lack of torque going up steep hills with an artic up your backside is flamin' illogical and dangerous, why not allow 750watt motors but keep the speed limit the same?

It's just a Bbs01b with the latest standard 20amp controller, afaik the b suffix 250w and 350w share the same controller (and possibly the 36v 500w), the difference is the factory programming ( note the codes on the top of the motor case) not the actual controller itself. There is no ETM 250w, it's marketing codswallop. As for extra thick wiring or something of the like, they're pulling your pants down trying to fool the gullible. Use your brain no manufacturer is going to custom build a motor that could lead to court cases for a small outlet for no fee are they?

The new controllers are programable mine came with a 20amp controller in the 250watt motor and after a bit of tweeking to the parameters I managed to get the 250w up to 684w at 18amp. This was purely for a test, and its now at a safer 15amp but still pulls a healthy 570watts. The controller codes are etched into the top of the case in newer BBS1/2 B's. 36v 250W C571-30-511 350W C571-30-513 500W C571-30-515 48v 500W C571-30-508(514) 750W C571-30-512 As mine came with a 20amp controller I'm guessing the actual physical controllers for the 250w and 350w are the same, and these codes are purely for the factory programming. Heres the ebay.uk link https://www.ebay.co.uk/itm/362924571189

Yeh me too, as my Scott is now un-rideable as I'm not re-installing the original Shimano crank only to take it out yet again when I get a working BBS02B...and my legs are flamin' killing me from all the kneeling down over the last couple of days.. think I've stretched the muscles or tendons.

Well I swapped the display from the BBS01b onto the BBS02b....that didn't work. I then swapped the wheel sensor....still nothing. I opened up the cover (after removing the crank arm, sprocket and drive cover.....the drive cover on my BBS02B blocks removal of the controller cover) and noticed the black connector wasn't firmly home, sitting at an angle. I duly opened the connector checked the pins where OK, re-assembled the connector making sure it was fully home, checked to see if anything else was loose (all OK) re-assembled the lot.....and nothing. Same as before the motor only spins up on the throttle! Luckily for me the ebay seller (treek-motor)accepts returns and postage free! So I then spent two hours dis-assembling the entire kit and re-packing the box (I hadn't thrown the original packaging away....phew!), so now its all packed up (a royal pain in the backside) with a printed pre-paid return label and I'm off to the Post Office to send it back to the return address in Leicester.

The UK law is vague...max 250w and a 15.5mph limit (25kmh call it speed A). But to get up a steep hill that same motor will be pulling far more watts, maybe 3, 4 or 5 X the rated power...example to get up a 10% hill the motors maybe pulling 500w+ at speed A...but only 175w on level ground at speed A......at what point is the motor illegal? The law doesn't and cannot define this...plus power IN is not the same as power OUT.....like having your foot down in a low powered car on a hill, you foots down to the floor, the fuel going in is high.....but your speed aint changing. And there is no laws as far as I know about changing the parameters of the motor as long as its rated at 250W from the manufacturer.

From my own understanding and measurements....your suffering from voltage sag (normal...how much depends on the cells in your battery) and your 'keep current' is way to low....when you set your max current in the BASIC menu, thats the absolute limit of current draw allowed into the motor, the 'keep current' is the programmed percentage of that limit, so if say, you have 20 amp set as your limit in the BASIC menu, 100% in the 'keep current' PAS menu will be the full 20 amps, 75% will be a maximum of 15 amps, 60% 12amps, 50% 10 amps etc.....its a safeguard measure... people get this mixed up with the current decay, which is valued at 1-8 (in the PAS menu)....this value will drop the amps going into the motor. Think of driving a car.....you accelerate up to a speed with your foot pressed down, then lift off when the speed you want is reached as you don't need as much power to maintain a constant speed. And although the BASIC tab and its 9 values look like your getting full power at level 9, your not, easily checked by looking at the wattage draw in your display. And as a side note, wattage draw into the motor is not equal to the wattage out at the wheel....but its the best we can get.

Cheers for that....I'll swap the display and wheel sensor first...then take a peek under that cover if that doesn't point to whats wrong...can it be removed with the motor in the frames BB...or does the motor have to come out?

Good idea, I'll try the display and the wheel sensor off the other bike (BBS01B) tomorrow. If that doesn't work its definitely an internal issue.

Thanks for replying. Yes I have a programming cable and all the parameters are fine (I checked....twice...carefully). I've never opened a motor up tho, which side of the motor does the PAS sensor plug fit, chain side, under the drive gearing? Any chance of a pic so I know what to look for?

Hi, I've just spent the weekend building up a Scott mtb with a BBS02b...but when it came to the first test ride...the PAS does not work..but the throttle does. I don't ride using the throttle..I only installed the throttle to check there was power whilst on the work stand! I've double checked all the connections, triple if not quadruple checked the wheel sensor for its gap right down to 1mm..the sensor lights up as the magnet passes (as it should) but still no PAS. All the parameters in the display are fine, no error codes. I've disconnected the throttle and brakes...and still no PAS. All the wiring is perfect etc (I built my road BBS01b a few months ago, which is great) so its not like its my first build. This is a brand new BBS02b with zero miles which I only received on Friday (October 1st). Any ideas or do I disassemble the BBS kit and send the lot back and ask for a refund (which would be a huge shame)? Help and advice appreciated!