Bafang m820

[Adam_TrailBK]

I installed GO+ and it wanted to update my controller. look at the voltage number...

 

[Freda]

I get this same message every time I start GO+. It wants me to update to a 36V firmware even if I am on 48V firmware.

 

[Dado]

A bug, and same in Besst. I did get only once an offer to update firmware from server, but also wrong voltage.

 

[tepe]

Hi guys, i'm preparing for first chinees bike order: CEF50 + M820, but few hours of reading i still don't know which battery setup i should choose:

• 36v
• 43v
• 48v

My options:
a) do more heavy setup: 720WH/36v or 700WH/48v (aluminium frame ~ 4kg)
b) light version: 48v/480wh, 36v/540wh (this is new setup in carbon frame, waight ~ 2,4kg)

Now i have shimano E7000 with 2 year old 504WH battery, and in 30% of rides i need to have charger with me, or i will be out of battery at he end of the ride.

My questions:

1. It's better to have 36v or 48V
2. Why bafang recomend 43V, and most of batteries are 36v or 48v ?
3. Doeas motor always need to have FW version that correspond with battery voltage ? Or it's possible to have battery 36V and 43V / 48V FW, (if yes, does it help?)
4. Water bottle range extenders, i read that it's possible only with 36V battery, true or false ?

 

[brbr]

Hi guys, i'm preparing for first chinees bike order: CEF50 + M820, but few hours of reading i still don't know which battery setup i should choose:

• 36v
• 43v
• 48v

My options:
a) do more heavy setup: 720WH/36v or 700WH/48v (aluminium frame ~ 4kg)
b) light version: 48v/480wh, 36v/540wh (this is new setup in carbon frame, waight ~ 2,4kg)

Now i have shimano E7000 with 2 year old 504WH battery, and in 30% of rides i need to have charger with me, or i will be out of battery at he end of the ride.

My questions:

1. It's better to have 36v or 48V
2. Why bafang recomend 43V, and most of batteries are 36v or 48v ?
3. Doeas motor always need to have FW version that correspond with battery voltage ? Or it's possible to have battery 36V and 43V / 48V FW, (if yes, does it help?)
4. Water bottle range extenders, i read that it's possible only with 36V battery, true or false ?

Hey,
I’ll let others comment but my thoughts :
1- tye higher the voltage, the lower the amps for a similar power, so less heat
2- they said it was a good compromise between heat management and cells placement in the battery casing
3- someone on the forum run a 48v battery on a 43v firmware, which allows to use (almost) all the capacity of the battery before the cutout , other mixing are not possible
4- you can find 36v and 48v easily, 43v they don’t exist and yiu’ll need to go diy

 

[tepe]

4- you can find 36v and 48v easily, 43v they don’t exist and yiu’ll need to go diy

Any recommended and tested 48V version? How to use this water bottle battery? It's plug a into charging port? Or it's more complicated?

 

[brbr]

Any recommended and tested 48V version? How to use this water bottle battery? It's plug a into charging port? Or it's more complicated?

it's a bit more complicated, you need to have a diode to ensure nothing will flow from the original battery to the range extender. Or you can just decide to plug the range extender when your main battery is lower in voltage than you range extender

 

[brbr]

I guess you can use that kind of battery bottle : 139.08￡ 31% de réduction|San yo Batterie pour moteur de vélo électrique, Mini bouteille, Bafang TSDZ2, 18650 W, 250W, 350W, 36V, 10,5 Ah, 9Ah, 48V, 7Ah, 500 Eddie ion ion | AliExpress

 

[mike_kelly]

There is very little room for a bottle battery on the CEF50 so be very sure a battery will fit before you purchase.

 

[tepe]

There is very little room for a bottle battery on the CEF50 so be very sure a battery will fit before you purchase.

Now i'm more convinced to 700WH / 48V, and don't bother with bottle battery at all. It's not so easy to decide what to choose...

 

[mike_kelly]

It is easy to choose. If you ride long epic rides then get the 720whr. If you ride short 1-2 hr rides then save weight with the smaller batteries. As noted before the higher the voltage the lower the current draw. But the limiting factor is the availability of batteries for a particular voltage chosen.

 

[Dado]

And soon will be available to use one-up cell battery with new K1 BBR device. (so 43V firmware and 48V battery or 48V and 52V battery)
With good SOC reading and even lower discharge capability - down to 3V per cell.

 

[kevinkeenan]

I have a BAFANG m820 motor and when I try to move the bike backwards or when it’s in the stand, rotate the rear wheel backwards, the motor has resistance and sound like I’m trying to spin the motor backwards. Like a grinding sound but not really grinding. Any thoughts?

 

[Neeko DeVinchi]

I have a BAFANG m820 motor and when I try to move the bike backwards or when it’s in the stand, rotate the rear wheel backwards, the motor has resistance and sound like I’m trying to spin the motor backwards. Like a grinding sound but not really grinding. Any thoughts?

I'm not having that issue in terms of resistance. I can hear a whining sound from the motor. But that's common on some geared motors.
Try moving the chainring anti clockwise with the chain somewhere in the middle of the cassette. You should only hear a whining sound from the motor. But the resistance should be minimal from the chainring/spider. Moving the back wheel anti clockwise or pushing the bike backwards and feeling resistance could be due too a motor issue. But it may be due to (but not limited to),
•rear wheel out of true,
•worn jockey wheels on the derailleur,
•an un-lubed chain, •freehub body engagement failure, •chainline misalignment,
•Bent derailleur,
•not having enough/having to much links on the chain,
•B-Tension screw on derailleur not set correctly,
•disk rotors rubbing on the brake pads,
Etc.
If it helps, I can quickly shoot a video demonstrating what mine sounds like and the little effort required to spin the back wheel with the chain on the chainring.
Bare with me

 

[Dado]

Kevin, thats just common behaviour of Bafangs. There is a clutch inside and when you ratate with chainring backwards, clutch is engaged and you spinning also rotor. Then it jumps over magnet poles and you hear a play in gearing and you feel resistance.

 

[mike_kelly]

You are essential using it as a generator when you pedal backwards. The resistance is in the magnetic pull in the windings.

 

[kevinkeenan]

I have a video but I’m not sure how to upload it yet. I’ll try searching around to figure out the video upload issue.
I’ve demo’d bikes with the same motor before and this isn’t normal. It’s not anything with the chain or wheel because when I remove them and grab the front spider and try to spin that backwards, it does the same thing. It’s very hard to turn backwards.

 

[kevinkeenan]

Video is in attached .zip file.

 

[Neeko DeVinchi]

Video is in attached .zip file.

Gottya. That doesn't sound right.

CEF50 EMTB with Bafang M820 system - 75NM TORQUE⚡️

A full video of this EMTB coming soon. Let me know if you have any questions👍🏿

youtube.com

32sec in the video, I turn the spider/chainring with minimal effort. You can hear a whining sound as well as the freehub engagement.

At present, my usual avenues for sourcing spare parts for bafang motors (GBK, Titan Pro etc), haven't stock piled parts specific for the M820 motor. But if it helps, I can make enquiries to see how best to get Your motor repaired or replaced.

Did you buy the motor through a random Alibaba or Aliexpress merchant?

Please kindly let me know, as this may determine whether my contacts can resolve the problem under warranty or not

 

[kevinkeenan]

Gottya. That doesn't sound right.

CEF50 EMTB with Bafang M820 system - 75NM TORQUE⚡️

A full video of this EMTB coming soon. Let me know if you have any questions👍🏿

youtube.com

32sec in the video, I turn the spider/chainring with minimal effort. You can hear a whining sound as well as the freehub engagement.

At present, my usual avenues for sourcing spare parts for bafang motors (GBK, Titan Pro etc), haven't stock piled parts specific for the M820 motor. But if it helps, I can make enquiries to see how best to get Your motor repaired or replaced.

Did you buy the motor through a random Alibaba or Aliexpress merchant?

Please kindly let me know, as this may determine whether my contacts can resolve the problem under warranty or not

I have a contact. Thank you for your help, though. I was just hoping it was something someone might have seen and we didn’t have to replace the motor.

Also, when I do what you did in the video, it takes two hands.

 

[Neeko DeVinchi]

I have a contact. Thank you for your help, though. I was just hoping it was something someone might have seen and we didn’t have to replace the motor.

Also, when I do what you did in the video, it takes two hands.

Personally, I'd look to get the motor serviced/repaired/exchanged if you're encountering that much resistance.
Currently, I've only put 200miles on my m820. But I'll bare your experiences in mind. I suspect your mileage is relatively low in the grand scheme of things.

Any issues or hick-ups, don't hesitate to reach out to me

 

[kevinkeenan]

Personally, I'd look to get the motor serviced/repaired/exchanged if you're encountering that much resistance.
Currently, I've only put 200miles on my m820. But I'll bare your experiences in mind. I suspect your mileage is relatively low in the grand scheme of things.

Any issues or hick-ups, don't hesitate to reach out to me

Mileage is 0.
Thank you for your assistance and offer to help.

 

[kevinkeenan]

All sorted. New motor did the trick. We will send defective motor back to BAFANG for inspection. Thanks!

 

[TCFlowClyde]

All sorted. New motor did the trick. We will send defective motor back to BAFANG for inspection. Thanks!

Nice...that was quick!

 

[Pinkee]

Hi everyone. I am trying to change the speed limit for the m820. it is currently set at 32. I want to change to 45. I have besst tool, but when I try to write the new limit it says "Dealer or assembler cant change to higher".

How is everyone changing the limit?

 

[Freda]

Hi everyone. I am trying to change the speed limit for the m820. it is currently set at 32. I want to change to 45. I have besst tool, but when I try to write the new limit it says "Dealer or assembler cant change to higher".

How is everyone changing the limit?

Install old version of besst from github and change it to whatever you want up to 60km/h. At least on version 1.2.20 it works.

 

[borysgo2]

Mod : Copied from another thread as it's useful.

The Motor is easy to open. First remove C clip at the drive side, than unscrew a few bolts around the housing.

There is no need to unscrew 3 bolts from the motor itself at non drive side.

When putting back together do not overtighten the bolts around motor housing.

 

[patdam]

It's the grease inside (lithium) or you have added it ?

 

[Zimmerframe]

It's the grease inside (lithium) or you have added it ?

You've not tagged him so he probably won't reply, but in the other thread he said :

"

Looks like professional work here. Did You already assemble the motor and do a test ride? Reduced noise level / whining?

I have done about 100km after I putt it back together. Noise level I roughly the same. Used molykote pg75 grease.

 

[patdam]

Tested yesterday. Clearly if you usually don't use the max power of M510, the M820 as a good choice. A little bit more noisly but very playfull use.
Those has been surprise me the most is the consumtion, near 2 x less than M510. clearly if you don't empty the 700W battery (keep 20 / 30 %), you can save weight by using 500W to do the same thing.

Other interesting point with the DPC263 HMI, you can easly choice qty of mode (3 / 5 / 9), has every choice can be parametred separately in BESSTpro, you can set several various functioning and easly change on track.

The bad points are that you can't use an throttle to have efficient walk mode. You can build an switch -, but as speed is too low, it's necessary to change also gears. Other bad point whith the DPC263, the human power input indication don't display value, i hope bafang will provide software update to allow that, it's very interesting information in add of motor power output and the cadency.