Bafang m820

[mike_kelly]

Yes, is a CAN bus battery, but looks like there is no CAN L/H at charging connector. Can connector is separate.

There are extra lines that could be the can data pair just not labeled correctly.
I wonder where the bus terminator is located and if it could be missing?

 

[sandnap]

I found the issue. I guess I was being a bit too aggressive when stashing the cables and severed the +/- wires.

Some dremel tool work:

Solder and epoxy:

And it's taking a charge.

Thanks again for all of your help.

 

[mike_kelly]

TIme to ride

 

[JimLee-Lightcarbon]

I found the issue. I guess I was being a bit too aggressive when stashing the cables and severed the +/- wires.
View attachment 133939


Some dremel tool work:
View attachment 133940

Solder and epoxy:
View attachment 133941
View attachment 133942
And it's taking a charge.

Thanks again for all of your help.

This cable is relatively stiff and can be easily broken.

 

[Dado]

There are extra lines that could be the can data pair just not labeled correctly.
I wonder where the bus terminator is located and if it could be missing?

Hello Mike. You mean 120 Ohm bus terminator? One is in a controller, other in display. No need to have in battery.
I guess Bafang did not add CAN communication to charger as it would be more expensive. But good for us they do not charging only after proper CAN handshake - like cars do. Wont be good if they lock controllers and would work only with original Bafang CAN battery.

I find that thermistor useless for charging currents up to 4A.

 

[mike_kelly]

Hello Mike. You mean 120 Ohm bus terminator? One is in a controller, other in display. No need to have in battery.
I guess Bafang did not add CAN communication to charger as it would be more expensive. But good for us they do not charging only after proper CAN handshake - like cars do. Wont be good if they lock controllers and would work only with original Bafang CAN battery.

I find that thermistor useless for charging currents up to 4A.

Even tho canbus was designed for a straight daisy chain I have used star topologies before. So was curious where they put the terminators. Makes sense to have one in display at the far end and one in motor. But it would seem one benefit of canbus is to be able query the battery for status rather than guessing and to have the charger query the battery during charge.

 

[LAnton]

Anyone with a Bosch Smart System e-bike can now customise peak torque, enjoy dynamic Kiox display, and access more data than ever before thanks to new update - MBR

Bosch’s latest e-bike system update is here, and it’s a good one, aimed squarely at making the standard Kiox display a whole lot smarter. Called Dynamic Display it works on the Kiox 300 and 500 displays and will deliver more useful riding data according to where you are in your ride. There’s...

www.mbr.co.uk

E-bike fires up 78% in a year according to the London Fire Brigade - here's how to keep your battery safe - MBR

E-bike fires increased by a massive 78% last year compared with 2022, according to the latest data from the London Fire Brigade (LFB), which has launched its #ChargeSafe campaign to try and control the problem. The capital saw 155 e-bike fires last year, and 28 e-scooter fires, while combustion...

www.mbr.co.uk

What a strange article. First they write about the Bosch engine, then they mention the fire. Do you think this is true? Maybe Chinese electric bicycles are to blame?

 

[Freda]

So I rode two rides this week, almost identical, about 37km. Temperature was same on both, couple of degrees below zero Celsius. The first one I used S+ mode all the way. The second I was on Eco mode all the way. Started both on 100% battery. The first I ended up with 16% battery left and the second on 19%. I don't get it.. The difference should be way more, only real difference is that the first one was faster, around ten minutes faster, 2:30h against 2:40h, but this could be due to drinking breaks difference, I was not racing on either of them.

I have had a feeling that the difference between the assist levels are not that big, but this looks like they are almost the same. Also when riding alone, I have just as fun on Eco as on Boost. I need to check besst or GO+ what my settings really are.

 

[Dado]

Freda, check max power settings, somebody maybe did mess with this. You definitely need to feel difference between levels, especially between Eco and Boost.

I have noticed last motor which was sent as a replacement to my friend was with 10A (43V) - looks like they realized 13A was too much.

 

[patdam]

Really completely diferent of my M820 feeling.

48V, 700W battery. my common using are high mountain +- 30km with +- 1300 D+. never consumed more than 22¨% ?

I use 48V14A software, i don't feel really differency on power, but i find it allow lower RPM than 48V09A (70 in regard of 85). my weight 100 kg, i climb on 10 / 20% at +- 7 km/h with 32 plate / 52 rear pignon (29¨).After several test, finally i don't use the boost, it quickly provide motor cut very troublesome. I mostly use trail (setted at 50%) and speed (setted at 80% %) and i clearly feel difference between the 2. I have setted speed+ at 90%, but finally i dont use it. The more i use M820/CEF50 and most i appreciate it, just Needs to gets used to motor capacity/functioning.

 

[Dado]

Really completely diferent of my M820 feeling.

48V, 700W battery. my common using are high mountain +- 30km with +- 1300 D+. never consumed more than 22¨% ?

I use 48V14A software, i don't feel really differency on power, but i find it allow lower RPM than 48V09A (70 in regard of 85). my weight 100 kg, i climb on 10 / 20% at +- 7 km/h with 32 plate / 52 rear pignon (29¨).After several test, finally i don't use the boost, it quickly provide motor cut very troublesome. I mostly use trail (setted at 50%) and speed (setted at 80% %) and i clearly feel difference between the 2. I have setted speed+ at 90%, but finally i dont use it. The more i use M820/CEF50 and most i appreciate it, just Needs to gets used to motor capacity/functioning.

Check the realtime power on your display. If match to 50% and 80%.
Anyway 48V and 14A is a lot for this motor.

 

[patdam]

Check the realtime power on your display. If match to 50% and 80%.
Anyway 48V and 14A is a lot for this motor.

I don't thing that would means 14A, I can't really see the power displayed on HMI (not stable) and when i''m apply strong effort i don't look (i need to see where i put my wheel) . but i never seen 5xx W and i don't see significative differency between 09 and 14 (displayed on HMI).

My feeling seem very different than other. I have recently performed an stress test and i reach 330W. Does it the reason of the difference ? how many you provide ?

 

[mike_kelly]

I higher the voltage the lower the amps will be, given the same power level.

 

[Freda]

The Watts displayed, are they what is provided by motor or total, rider + motor?

I can reach 500+W fairly easy.

 

[Freda]

So I checked in Besst Pro, I had all levels on full power:

This means whatever I change in GO+ has no effect on controller. Only speedlimiter seems like it is actually doing something. My GO+ connects fine and everything seems to work, even changes made are "succesful".

I changed the assist levels in Besst Pro, to more or less same as @Neeko DeVinchi had. I went for a ride and now the difference between levels are huge! Still need to test the acceleration setting, what feels best.

On the positive side, this means I have done 3h rides with full power(boost) without overheating the motor or noticing any power drops.

 

[Freda]

Really completely diferent of my M820 feeling.

48V, 700W battery. my common using are high mountain +- 30km with +- 1300 D+. never consumed more than 22¨% ?

I use 48V14A software, i don't feel really differency on power, but i find it allow lower RPM than 48V09A (70 in regard of 85). my weight 100 kg, i climb on 10 / 20% at +- 7 km/h with 32 plate / 52 rear pignon (29¨).After several test, finally i don't use the boost, it quickly provide motor cut very troublesome. I mostly use trail (setted at 50%) and speed (setted at 80% %) and i clearly feel difference between the 2. I have setted speed+ at 90%, but finally i dont use it. The more i use M820/CEF50 and most i appreciate it, just Needs to gets used to motor capacity/functioning.

How do I know if I have 48V09A, 48V14A or something else? Is it the number after 48 in software version? So 48V09A then?

 

[patdam]

How do I know if I have 48V09A, 48V14A or something else? Is it the number after 48 in software version? So 48V09A then?
View attachment 134973

True, normally the 2 digit after the power supply are the max A available, but i don't feel really that after testing the 2 ? i just find efficient motor help at lower RPM range with the 4814
So, with 48V09A you can stay in boost and climb over 500W during all time ? impossible with mine.
How many weight you have ?
you climb how many % in boost ?
at wich speed ?
wich legs RPM ?
Do you know how legs power you provide (measured on stress test) ?


your answers could help me to understand

 

[Dado]

So Freda, now you know why you did feel it the same. So you must have had also bad range.

Yes, that Go+ works weired, but I must say it worked for me, when I tested with M510. So should be working also on M820. What I noticed it didnt sometimes read the settings, I had to click forth and back and then it went updated. Did analyse CAN traffic from display, It was sending setup packets to motor.

Put acceleration on full. It is the steepness of startup current. For a short period of time (<2s). So dont expect any difference in acceleration from lets say 20kmh to 30kmh.

You have 9A. Try 12A. Should be peaking 600W Very good for such a small motor.

 

[Freda]

True, normally the 2 digit after the power supply are the max A available, but i don't feel really that after testing the 2 ? i just find efficient motor help at lower RPM range with the 4814
So, with 48V09A you can stay in boost and climb over 500W during all time ? impossible with mine.
How many weight you have ?
you climb how many % in boost ?
at wich speed ?
wich legs RPM ?
Do you know how legs power you provide (measured on stress test) ?


your answers could help me to understand

So earlier I could easy push over 500W, but not keep it for long time. It would take a steep hill and we don't have that where I live and my stamina is not good enough for that. When the speed is rising, the motor assistance drops, I have 35km/h limit.
I weigh 90+kg geared up.
Not much climbing here, mostly under one minute climbs.
Cadence up to 100, but normally 70-90 I think. I got short cranks, 152mm.
I haven't measured anything about my power.

 

[patdam]

So earlier I could easy push over 500W, but not keep it for long time. It would take a steep hill and we don't have that where I live and my stamina is not good enough for that. When the speed is rising, the motor assistance drops, I have 35km/h limit.
I weigh 90+kg geared up.
Not much climbing here, mostly under one minute climbs.
Cadence up to 100, but normally 70-90 I think. I got short cranks, 152mm.
I haven't measured anything about my power.

thanks, difficult to compare, too many différence (ground, climb, speed limit), here it climb or down hard, i avoid flat parts .

 

[Freda]

So Freda, now you know why you did feel it the same. So you must have had also bad range.

Yes, that Go+ works weired, but I must say it worked for me, when I tested with M510. So should be working also on M820. What I noticed it didnt sometimes read the settings, I had to click forth and back and then it went updated. Did analyse CAN traffic from display, It was sending setup packets to motor.

Put acceleration on full. It is the steepness of startup current. For a short period of time (<2s). So dont expect any difference in acceleration from lets say 20kmh to 30kmh.

You have 9A. Try 12A. Should be peaking 600W Very good for such a small motor.

I tried this firmware, thanks! I rigged my camera to film the display since it is hard to watch while riding. I managed 607W maximum on Boost mode, so seems correct, 48V x 12A = 576W. So about 100W more than previous 48V09A.
On other assistlevels it drops about 20% per level as I have put them with Besst Pro.

So now I just need to do some real trail riding to get a better feeling of how it works.

 

[Dado]

Yes, first few minutes you have sag 50V. So can be peaking over 600W. And so is Bosch motor. So Bafang is catching...
150W more. +3A

 

[Freda]

I tried this firmware, thanks! I rigged my camera to film the display since it is hard to watch while riding. I managed 607W maximum on Boost mode, so seems correct, 48V x 12A = 576W. So about 100W more than previous 48V09A.
On other assistlevels it drops about 20% per level as I have put them with Besst Pro.

So now I just need to do some real trail riding to get a better feeling of how it works.

So an update to this, did two rides, same terrain similar distance and time. First one 45% battery left with mostly in assist level 3 and second one on assist level 2/3 ended up with 48%. So everything seems fine now.

One note is that 20% assist on Eco mode is really low, it feels like the battery saving mode when battery runs low. If I remember correct bafang default is 40% on Eco.

 

[atkk]

Has anybody had an issue with pedal assist suddenly not working at all? I had 2 good rides, fully charged today, but after power on there is no motor assistance in any modes. Walk mode works fine, and I tried changing some power settings in the GO+ app, but it didn't have any affect. It seems like an issue with the torque sensor.

 

[Dado]

Hello Freda.

20% should be around 120W at PAS 1 in your case. This sounds good for me for maximizing range. Bosch also giving around 100W at Eco.
Last M820 we set with customer to 14% at PAS1 and then more fine next 2 levels. He was almost not riding PAS4 and PAS5. So depends according preference.

Out of topic: Already contacted me 3 people with M820 and requested about BBR. Would somebody else be interested? Check www.k1ebikes.com for more info about BB Racing.
I need to rework for speed connectors if some more demand - now it is designed to middle violet connector, which M820 does not have.

 

[keyne]

Does anyone know how natural the m820 torque sensor implementation is compared to a Specialized Levo SL? I’m trying to convince my wife to trade in the Specialized for a m820 bike and she is worried it won’t be as smooth and natural feeling.

 

[NCMTB Rider]

Need some help!
Bafang Battery F014.410 arrived today so I am almost complete with my build but ran into trouble similar to others regarding the wrong cable sent with the motor kit. The wire sent was 1t2 (motor split to display and light). Anyone have the correct wire in the USA? I need the wire from motor to display, light and battery (Round green). Anyone know where to get one as I work with vendor in China? I can for go the light wires with wiring from motor to display and battery…..

 

[NCMTB Rider]

Picture of battery wires on left and incorrect wire on right.

 

[mike_kelly]

Does anyone know how natural the m820 torque sensor implementation is compared to a Specialized Levo SL? I’m trying to convince my wife to trade in the Specialized for a m820 bike and she is worried it won’t be as smooth and natural feeling.

If it helps I can say that the M820 is not as smooth as the Rise EP8R. Not bad at all but not better.

 

[temon10]

Does anyone know how natural the m820 torque sensor implementation is compared to a Specialized Levo SL? I’m trying to convince my wife to trade in the Specialized for a m820 bike and she is worried it won’t be as smooth and natural feeling.

If compared with Levo SL just buy her Levo SL before she complained hahahahaha...