Bafang m820

brbr

Active member
Dec 28, 2022
529
269
France
just a question, on the old BTF014, I can't see any connectors, neither charge or discharge, do you know what is the interface needed to use it ?
 

stuff

Active member
Nov 3, 2022
166
281
Spain
just a question, on the old BTF014, I can't see any connectors, neither charge or discharge, do you know what is the interface needed to use it ?

There it is a big connector that uses two screws. Charge/discharge are the biggest pins in both sides
 

brbr

Active member
Dec 28, 2022
529
269
France
There it is a big connector that uses two screws. Charge/discharge are the biggest pins in both sides
you know where i could find an adapter to use this battery? By adapter I mean, the male connectors that goes to the motor with the xt30 and that goes to the charge port.
I’ve found an old btf014 version but sold without charger nor adapter
 

brbr

Active member
Dec 28, 2022
529
269
France
guys, I don't know which battery to choose 12s3p or 10s4p? does the use of 43V have any advantages?
in theory, lower current, less heat, with the higher voltage.
It depends which frame you want and if you wanna go custom and if you want a range extender
 

Polak_B

New Member
Jun 21, 2023
15
3
POLSKA
CEF50. My plan is that the battery should not exceed the weight of 3kg. I buy the housing itself and I will give it to a friend to make me a battery. I need range and weight no more than 3kg. I will add that the engine will be unlocked to speeds above 25 km / h

that's why I'm thinking whether it's better to use 36V or 43V.
 

brbr

Active member
Dec 28, 2022
529
269
France
CEF50. My plan is that the battery should not exceed the weight of 3kg. I buy the housing itself and I will give it to a friend to make me a battery. I need range and weight no more than 3kg. I will add that the engine will be unlocked to speeds above 25 km / h

that's why I'm thinking whether it's better to use 36V or 43V.
You have a bigger choice of bms with 36v, but you can also easily find 43v bms.
For the speed, I guess you will require a high power, so more amps with 36v. You will probably go for 3 or 4p so it shouldn’t be a problem I guess if you take good cells. Even 10A cells, will give you 3x10x36=1000W+ in 36v, which is more than enough
 

LAnton

Active member
May 12, 2022
550
458
Russia
CEF50. My plan is that the battery should not exceed the weight of 3kg. I buy the housing itself and I will give it to a friend to make me a battery. I need range and weight no more than 3kg. I will add that the engine will be unlocked to speeds above 25 km / h

that's why I'm thinking whether it's better to use 36V or 43V.
If you buy a 720W battery, give an empty case to a friend, then your battery will weigh 3 kg. But you need to figure out how to fix it in the frame.
 

brbr

Active member
Dec 28, 2022
529
269
France
Does anyone know where I can find a female bafang connector to use with a bafang 43v charger?

2a-chargeur-pour-batteries-bafang-43v-chg-c01-2a.jpg
 

clix

Active member
Jul 24, 2022
186
207
EU
In this thread, it looks like there is consensus, that 36V and 43V are exactly the same, apart from the FW difference. Is there any proof, that this is correct? Usualy, motors for different voltages are wound differently (different stator and rotor - different number of magnetic poles) so with the rated voltage, output speed will be the same. Contoller can be the same, and it can be reflashed with different FW, so it will accept another voltage range. But this doesn't mean, that performance will be identical. For example, with different voltage applied, max power of the motor can be in different cadance ranges, than designed.

So, do we know, that the actual stator and rotor of 36V and 43V motors are the same?
 
Last edited:

clix

Active member
Jul 24, 2022
186
207
EU
Also, was anybody actually successful of sourcing different firmwares for M820 motors?
 

clix

Active member
Jul 24, 2022
186
207
EU
No, works at 52V, whitch is just sligthly higher, than full 12s, 43V battery (12 x 4.2 = 50.4V).
 

clix

Active member
Jul 24, 2022
186
207
EU
Oh, I understand the confusion now. In this case, I didn't connect the motor to the battery. I don't have that battery and charger yet. I connected it to laboratory power supply so I checked the FW version. And I set 52V and it worked.
 

clix

Active member
Jul 24, 2022
186
207
EU
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?
 

temon10

Well-known member
Feb 8, 2022
672
560
Malang, Indonesia
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?

It rattle but not as loud as EP8. Still tolerable for me.
 

brbr

Active member
Dec 28, 2022
529
269
France
Hey, I dont’ have a video right now, but do you have the weird sound when the assistance is starting /stoping? It’s like a metallic noise, very hard to describe…
 

brbr

Active member
Dec 28, 2022
529
269
France
Guys, did someone checked the voltage provided by the light cables ? I'd light to buy a light for winter evening rides, but they do not all accept all voltages
 

clix

Active member
Jul 24, 2022
186
207
EU
@brbr did you find any suitable light?
I am also interested in this. So far, I found this one:
It has 5.6w, so it should work OK.
It is StVZO compliant, meaning it has a sharp cut off line. It is great for the road riding, but It might not be the best for the trails..

Its big brother, pro-e 140 also has a high beam, but the wattage is to high. IMO, to have something trail worthy, we will have to splice the connection from the battery and use step down DC/DC to lower the voltage.
 

brbr

Active member
Dec 28, 2022
529
269
France
@brbr did you find any suitable light?
I am also interested in this. So far, I found this one:
It has 5.6w, so it should work OK.
It is StVZO compliant, meaning it has a sharp cut off line. It is great for the road riding, but It might not be the best for the trails..

Its big brother, pro-e 140 also has a high beam, but the wattage is to high. IMO, to have something trail worthy, we will have to splice the connection from the battery and use step down DC/DC to lower the voltage.
seems nice but only 550 lumen, that's low in full darkness.
I think I will go for Magicshine mj906s, not extra expensive but it seems very good
 

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