Modify Bafang BBS01B 36v for 44v

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This may help some people who like me are handicapped by the 78 RPM limit of the Bafang BBS01B motor. My natural cadence is around 90 RPM and I select a gear which allows me to spin at that speed when climbing. If you do spin at 90 RPM the motor becomes a generator (back EMF effect) and stops providing assistance... :rolleyes:

This modification is from the endless sphere "all things electrical" forum.

If you try to plug a 48v battery into the motor you will get a 07 - over voltage error on your LCD display. The display only detects the voltage coming from the controller, not the voltage going to the controller from the battery so all we need to do is tell the LCD that the voltage is less than 44.6v, which seems to be the limit set by Bafang for a 36v battery.

Why not use a 48v battery and gain 33% more RPM? Well that is a little too fast for me - >103 RPM at 48v. I had made a 44v battery for my previous motor which had the exact same problem and that is a 22% increase so 95 RPM at 44v. The common KT controller does not have very sophisticated over voltage protection so the 36v controller will just go "pop" with a little bit of blue smoke if you plug in a fully charged 48v battery, so this kind of modification was not needed.

I had some problems identifying the colour of the wires inside the LCD cable until I took it outside in the daylight... :rolleyes: but I found this plug schema on the internet

bafang-display.png

We are interested by the brown wire and not the orange one (which looked red inside with artificial light). PS my yellow wire is in fact white.

Then you need a TVS diode (Transient Voltage Suppressor) which comes with a large choice of breakdown voltages. For my battery 6v is the ideal number - maximum charge 49.8v - 6v = 43.8v. The diode is soldered inline on the brown wire with the band away from the LCD like so:

TVS-diode-hack.jpg

The reading on the LCD when I tested just now was 40.5v and on the watt meter connected to the battery 46.9v.

So what can go wrong?

- your LVC (low voltage cutoff) on the LCD will be affected. If it is set to 30v that is not much of a problem with the 12S 44v battery I have. You could wire in a bypass with a switch to turn off the diode when your real battery voltage reaches 42v.
- the reading on your display will not show the correct voltage. Mentally you can add 6v or just ignore the voltage display because on my LCD it isn't correct even before the modification... I prefer reading my battery voltage from the watt meter which I always have plugged inline.
- the TVS diode gets rid of the excess 6v as heat but the current is tiny so it should never be above 90ºC. As you can see I will cover the diode with heat shrink tube and inside the vélomobile it is protected from the weather.

And the motor? From previous experience the motor will have more punch, my previous motor even ran more quietly at 44v than when at 36v. If you spin at a slower cadence - 60 to 70 RPM - there is no real advantage.

So all I need to do know is road test and enjoy the comfort of using my natural cadence once again. :giggle:
 
??? der BBSxx hat einen Freilauf zwischen Kurbel und Motor. ;)

So I thought. On the road if I try and pedal up the hill just opposite me in a gear allowing me to spin at 90 RPM and with a speed (well) under 25 km/h the motor will cut out and the display shows 0 Watts.

Example: Alfine 8 52:16 in 1st gear speed at pedal 90 RPM = 15 km/h.

If I drop my cadence to 60-70 RPM the motor starts to provide assistance and the speed is 10-12 km/h so I change up to second gear to get the 15 km/h. There are not enough Watts in the standard programming to go much faster than that on that particular hill.

The GSMoon functions in exactly the same way and the number of times the motor cut out in the middle of a climb pushed me to increasing the battery voltage and thus the operating RPM of the motor to within my preferred cadence.

Edit

I think I see what is happening, as long as the motor side is told to stay energised by the controller because the speed is not >24 km/h the freewheel is engaged. Is it coupled to a clutch?

PS there have been successful experiments with BBS02 36v motors and 52v batteries, you just need a 14v TVS diode
 
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Du solltest das mal im Pedelec Forum posten.
Ich denke du wirst ganz schnell die Antwort bekommen dass der Motor so nicht lange halten wird.
Ich wäre dann auch sehr vorsichtig mit den Farben weil da gibt es auch unterschiedlichste Versionen vom Kabelbaum.
Es ist doch dann viel schlauer gleich den BBS02 zu nehmen der ja lieber die höheren Kadenzen mag.
 
I would agree if I was also using more than 13 Amps of current. My motor has not been reprogrammed and is still pretty anemic. Using a BBS02 is not legal on French roads and it also weighs a lot more.

At the moment the only thing wearing out faster are the bearings because there are more RPM. :giggle:
 
I went looking for a Bafang programming cable and 130 BCD spider earlier and in the list of motors sold by the company that sold me my Bafang there is now a 48v 250W BBS01B. It still has the ridiculous 78/83 RPM loaded speed though.
 
I'm currently playing with the open source firmware on my new TSDZ2 - precisely to avoid the cadence limitations imposed by the BBS01. Unfortunately I also had to rework the front derailleur - and can now not get the chain onto the big ring anymore. The moral of the story? Don't touch something that still works (or leave more time than you think you need for any repair!)
Cheers,
Phil
 
there is now a 48v 250W BBS01B. It still has the ridiculous 78/83 RPM loaded speed though.
According to Bafang, but from others I hear/read it gives power at higher cadence/RPM's. What would make sense to me because of the higher voltage.
Did you check/find out for yourself?

Laut Bafang, aber von anderen, die ich höre / lese, gibt es Leistung bei höheren Trittfrequenzen / Drehzahlen. Was für mich Sinn machen würde wegen der höheren Spannung. Hast du selbst nachgeschaut/gefunden?
 
No. https://bafang-e.com/en/oem-area/components/component/motor/mm-g340250350c/ is the one I have and what I get is very close to the spec sheet so there is no reason to doubt the numbers they are giving are not correct.

At the present I am waiting for a reseller to offer the M820, 1.5 kg lighter, decent torque and reported to support 120 rpm cadence. If the price is right I will upgrade to one of those.


What I don't like is the bluetooth control system even though it means less wires. For mounting I imagine 2 plates bolted to the 40 x 40 tube, the motor is slightly wider than 40 mm at the mounting holes it seems from the drawing on the web site but some spacers fix that. Offset? Move the sitting position 20 mm to the left, you can do that in Agilo ;)
 
in regard of the 820 , are there sources for short isis cranks ? i run a bbs02b 48v 350w for the higher cadence support (still not really what i want it to be but better then the 250w ) and the eggrider v2 display so i can limit it to 25 kph and 250w as a legal mode ( and unlock it to full power off road with my cell phone ) . 110 bcd adapter and 53 tooth ( realy should get a 130 bcd and at least a 57 tooth for higher top speed . ) .
 
in regard of the 820 , are there sources for short isis cranks ? i run a bbs02b 48v 350w for the higher cadence support (still not really what i want it to be but better then the 250w ) and the eggrider v2 display so i can limit it to 25 kph and 250w as a legal mode ( and unlock it to full power off road with my cell phone ) . 110 bcd adapter and 53 tooth ( realy should get a 130 bcd and at least a 57 tooth for higher top speed . ) .

Miranda make short 152, 160 isis cranks for about 60€.

Notice that the 4 arm 110 BCD is the new Shimano standard. Stronglight make 55T chainrings for that and you can find 60T in China.
 
Du solltest das mal im Pedelec Forum posten.
Ich denke du wirst ganz schnell die Antwort bekommen dass der Motor so nicht lange halten wird.
Ich wäre dann auch sehr vorsichtig mit den Farben weil da gibt es auch unterschiedlichste Versionen vom Kabelbaum.
Es ist doch dann viel schlauer gleich den BBS02 zu nehmen der ja lieber die höheren Kadenzen mag.
warum sollte der MOtor weniger lang halten ?
wegen der paar PRozent mehr Drehzahl ? das wird den lagern und Zähnen ziemlich egal sein..
wichtig sind die Ampere/Drehmoment
 
My previous motor, a BBS01 clone ran quieter and smoother with a fully charged battery when I removed the 25 km/h limit. I suspect the BBS01 would be the same I haven't tried yet. That is because the motor is running in the power band it was designed for, it probably delivers >90% efficiency too, instead of the 80% efficiency of a speed limited motor.

When you hotrod an electric motor the best plan is to stay within reasonable limits, let's think about the BBS01:

- a 36v battery fully charged is 42v
- a 44v battery fully charged is 50.4v
- the capacitors on the BBS0x controller are said to be 60v, the first generation were 50v so I only charge to 49.2v just in case (it's Chinese ;) )
- my 44v battery "empty" is 36v

So most of the time I am running the motor at between 46v and 42v, that is where the discharge curve of my cells is almost flat. The charge drops from 49v to 46v very quickly over the first 10-15 minutes of use. Once I get to around 40v it drops off very quickly and at 36-37v the modification I made above tells the controller the battery is at 30v so it cuts the power.

Raising the voltage makes the motor turn faster but does not increase torque or low end power (adding more amps will do that). That does not matter because a human spinning at around 87-93 rpm is at the cadence where (s)he produces the most power.

In conclusion there is probably less stress put on my motor than one running at 70 rpm (or less) because I am able to provide more power myself at higher cadence.
 
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