Bafang m820

patdam

Well-known member
Jan 17, 2019
902
601
france
They have a nice ebike light quite cheap, but it only works with a converter box… not on the dediacted light cables :(
Not sure the box will fit anywhere in the bike
ask it, it build all himself and it have great knowledge on this subject and he like to share it. He have showed me one time those used the the trail running mans and we can see as if we were in full day, impressive
 

clix

Active member
Jul 24, 2022
186
207
EU
The loam woolf just dropped the review of forestal siryon, with sister version of bafang M820, eon drive:



They mentioned, that on the last day, during the climb, in the trail mode, motor started derating power, because it was too hot. At the end of the climb, power output was minimal, but after it cooled down, it went back to normal. I am curious if maybe somebody else also noticed this with their m820?
 

Rob Rides EMTB

Administrator
Staff member
Subscriber
Jan 14, 2018
6,260
13,700
Surrey, UK
Guys, anyone has news about the Bafang 43v BTF014 battery ? My Alibaba seller says that bafang does not give them any news ... It's very frustrating.
I received mine today

5FFF03D1-86B1-4167-A9D6-9E954B0CB9C4.jpeg
 

brbr

Active member
Dec 28, 2022
529
270
France
So I finally decided to buy the Magicshine ME2000 which is not the brightest light you can find but 12KCD and 2000 lumens should be a good start.
The problem is that the Bafang m820 only provides a very low power output from the light cables so I bought a DC-DC converter from Aliexpress with an output of 12v 3A. The other problem I did not anticipated is the fact that the light is always on when there is power, and as it's plugged on the bike battery, there will always have power!
So I bought a DC 12v relay and I will plug the trigger switch on the light output of the bafang, in this way I will be able to control the lights from the display.
I'm waiting for all the parts now, I'm hoping to finish this by the end of the month
 

brbr

Active member
Dec 28, 2022
529
270
France
Guys, here is the noise I have when the motor engages and disengage.
Do you have this?
 

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petkevich

Member
Jun 6, 2023
29
24
San Diego
Hey guys, do you notice a motor rattle, when coasting on rough ground? I did the first run today, without a battery and there was quite an annoying rattling sound present. It was quite pronounced. I would say it is very similar to EP8 rattling noise (based on what I read and saw on youtube). It sounds like a loose ball bearing is hitting something. it is not chain slap and also nothing in my frame rattling. It feels like an empty hollow downtube amplifies the noise and makes it even more annoying.

Any similar experiences?
Yes noticed today on my 1st ride
 

Mowgli_Supertramp

New Member
Jun 15, 2023
4
0
Uk
Does anyone have a CAD model or a good drawing of the motor? I am trying to design a custom Ti frame for this motor but struggling with the motor interface, and in particular the bottom and side covers. Thanks!
 

clix

Active member
Jul 24, 2022
186
207
EU
Guys, here is the noise I have when the motor engages and disengage.
Do you have this?
Hey,

I noticed, that I have verry similar noise. To me, it looks like it is coming from the same freehub/ratchet, that is causing the motor to rattle, when free-coasting over rough terrain. Does your motor also rattle?
 

forsa355

Active member
Jan 31, 2023
62
116
Canada
Hey,

I noticed, that I have verry similar noise. To me, it looks like it is coming from the same freehub/ratchet, that is causing the motor to rattle, when free-coasting over rough terrain. Does your motor also rattle?
I've noticed the same noise. At first I thought I have some cables slapping around in the frame, but it's really when the motor engages. Sounds l like marbles spinning inside the hollow frame :). Also have the clunk over bumpy terrain. I wonder if this is just par for the course with the M820?
 

patdam

Well-known member
Jan 17, 2019
902
601
france
I've noticed the same noise. At first I thought I have some cables slapping around in the frame, but it's really when the motor engages. Sounds l like marbles spinning inside the hollow frame :). Also have the clunk over bumpy terrain. I wonder if this is just par for the course with the M820?
Please can you mention (those who have noise and those haven't) your firmware references ?
 

clix

Active member
Jul 24, 2022
186
207
EU
I've noticed the same noise. At first I thought I have some cables slapping around in the frame, but it's really when the motor engages. Sounds l like marbles spinning inside the hollow frame :). Also have the clunk over bumpy terrain. I wonder if this is just par for the course with the M820?
Yes, exactly like few loose marbles or ball bearings
 

Freda

Active member
Feb 5, 2023
162
139
Vaasa
Does anyone have some actual info on peak watts on this motor? Building the battery soon and I have 13S3P configuration, with INR21700-M50LT cells. They can manage 14,4A, but in lower temperatures only 2,4A!

  • -20 … +10°C: 2400 mA (2,4 A)
  • +10 … +25°C: 14400 mA (14,4 A)
  • +25 … +55°C: 7200 mA (7,2 A)

So that would make 2,4A*3*48V = 345,6W

Is this enough I wonder? Maybe I just need to take it easy in the winter..
 

brbr

Active member
Dec 28, 2022
529
270
France
Does anyone have some actual info on peak watts on this motor? Building the battery soon and I have 13S3P configuration, with INR21700-M50LT cells. They can manage 14,4A, but in lower temperatures only 2,4A!

  • -20 … +10°C: 2400 mA (2,4 A)
  • +10 … +25°C: 14400 mA (14,4 A)
  • +25 … +55°C: 7200 mA (7,2 A)

So that would make 2,4A*3*48V = 345,6W

Is this enough I wonder? Maybe I just need to take it easy in the winter..
In boost you get around 540W
Also, why are multiplicating per 3?
 

Waynemarlow

E*POWAH Master
Dec 6, 2019
1,108
889
Bucks
Does anyone have some actual info on peak watts on this motor? Building the battery soon and I have 13S3P configuration, with INR21700-M50LT cells. They can manage 14,4A, but in lower temperatures only 2,4A!

  • -20 … +10°C: 2400 mA (2,4 A)
  • +10 … +25°C: 14400 mA (14,4 A)
  • +25 … +55°C: 7200 mA (7,2 A)

So that would make 2,4A*3*48V = 345,6W

Is this enough I wonder? Maybe I just need to take it easy in the winter..
Its going to be tight when you initially use the bike but do remember as the batteries are begun to be used, they do generate some heat and will soon be up to a useable working temperature.

From experience when a battery is at these limits, it maybe better to choose a different type, remember that a manufacturer will test a battery in ideal conditions. Our use in an EBike is anything but.
 

Freda

Active member
Feb 5, 2023
162
139
Vaasa
Its going to be tight when you initially use the bike but do remember as the batteries are begun to be used, they do generate some heat and will soon be up to a useable working temperature.

From experience when a battery is at these limits, it maybe better to choose a different type, remember that a manufacturer will test a battery in ideal conditions. Our use in an EBike is anything but.
I will store/charge it in warm garage, so initially it will be ok, maybe just better to skip the really cold days.

A bluetooth bms with temp sensor would be one way to find out the actual temperature while riding.
 

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