Over volting bafang g062 to 72V

Snacks

1 W
Joined
Feb 2, 2022
Messages
54
Hi,

I’ve just recently laced up a bafang g062 1000w 6T to a 20in fat bike wheel. After doing some research, it seems like over volting this to 72v might be a bad idea. However, most posts I’ve seen about over volting a geared hub motor are from about 5 years ago and they’re discussing the older bmc 600w or Mac motors. I noticed a couple people here have got the g062 up to 60v with no heat issues. So I was curious if taking this to 72v would be as big of a problem today as it was years ago? I don’t plan on going more than 30A at 72v. I currently run it at 48v 45A and haven’t had any heat issues after a couple hundred miles.

First and foremost, if I was a smart or patient guy I would have probably asked this question or decided on a final build before purchasing this motor and probably would have gone with a DD motor . But it is now clear I am neither of those :lol: and as such I gotta work with this motor.

I’ve been reading the biggest challenge is dealing with heat, both in the phase wires and stator. I figured I could drill holes in the motor casing for better ventilation and possibly replace the phase wires for a thicker gauge. Although I’m not sure how big I can go while having them still fit through the axel .

The next thing would be playing with acceleration so as not to melt the nylon gears. Or if anyone would happen to know where to get metal gears for this motor? I saw a video of a tear down of a g062 750w and they measure 48mm planetary gears and a 88mm clutch. I will open it up on my next day off to confirm these measurements are accurate.

I just put together a 72v 20Ah LiFePo4 battery with a 100A BMS and trying to find a decent 72v 45-100A sine wave controller like the phase runner or a sabvoton around~$150. (It seems like an almost impossible price point) Hoping to program it to keep amps around 30A. Although if modifying the motor helps keep it cool, might try it up to 35 or 40A. Only reason I’m looking for a higher amperage controller is that I plan to move the controller/battery over to a new frame once it’s done being fabricated. However, I’d like to keep this as a 72V system and use a cheaper sabvoton mL 45A controller (if this all works out) for my buddy to use.

Any wisdom, comments , criticisms, advice , help or anything in between is greatly appreciated!
 
How fast is it supposed to be at 72V?
72V 30A is just a little over 2kW, I suppose that is enough for maybe 55-60km/h.
Not much idea going to a higher voltage than you have power to use.

My advice is to go the calculator at grins site and play with the numbers and see what is reasonable.
 
j bjork said:
How fast is it supposed to be at 72V?
72V 30A is just a little over 2kW, I suppose that is enough for maybe 55-60km/h.
Not much idea going to a higher voltage than you have power to use.

My advice is to go the calculator at grins site and play with the numbers and see what is reasonable.

im not sure how fast it supposed to be. currently top speed is around 26mph.
i would be very happy if it got me 55-60km/h
I tried to play around with the calculator but it didnt have the g062 listed and im not sure where to get the data to type in a custom motor. so i used the g060 and play around with it but i know thats not going to give me accurate numbers.

i guess ill just give it a shot when i get a controller and see how it goes. ill try to get a temp monitor of some kind in there to watch the heat while i try it out
 
Snacks said:
j bjork said:
How fast is it supposed to be at 72V?
72V 30A is just a little over 2kW, I suppose that is enough for maybe 55-60km/h.
Not much idea going to a higher voltage than you have power to use.

My advice is to go the calculator at grins site and play with the numbers and see what is reasonable.

im not sure how fast it supposed to be. currently top speed is around 26mph.
i would be very happy if it got me 55-60km/h
I tried to play around with the calculator but it didnt have the g062 listed and im not sure where to get the data to type in a custom motor. so i used the g060 and play around with it but i know thats not going to give me accurate numbers.

i guess ill just give it a shot when i get a controller and see how it goes. ill try to get a temp monitor of some kind in there to watch the heat while i try it out
I use the same motor. Over 1500 HARD off-road miles.
Initially I was going to run mine at 52V. I ended up having to DROP voltage to 44V!
Motor spins too fast for a 26x4" fat-tire build.
Controller maximum amps delivered to motor is 35 amps. Max speed is 32mph.
For Moto-Calc, use 9.3Kv and .045-ohm in custom motor setup.
What controller are you using in MotoCalc?
Simulation2 level ground no wind.jpg
 
pullin-gs said:
I use the same motor. Over 1500 HARD off-road miles.
Initially I was going to run mine at 52V. I ended up having to DROP voltage to 44V!
Motor spins too fast for a 26x4" fat-tire build.
Controller maximum amps delivered to motor is 35 amps. Max speed is 32mph.
For Moto-Calc, use 9.3Kv and .045-ohm in custom motor setup.
What controller are you using in MotoCalc?
Simulation2 level ground no wind.jpg

Thanks for those numbers for the motor! I was just inputting a custom controller based on what I wanted to run with a phase runner vs another custom input with values mimicking my current 48v 45A controller .

When you say it was too fast for a 26” wheel, was it causing problems going that fast or did you just not want a bike that fast?

Oh and I remember seeing a post where you were looking for replacement gears for this motor, did you ever find them?
 
Snacks said:
Thanks for those numbers for the motor! I was just inputting a custom controller based on what I wanted to run with a phase runner vs another custom input with values mimicking my current 48v 45A controller .

When you say it was too fast for a 26” wheel, was it causing problems going that fast or did you just not want a bike that fast?

Oh and I remember seeing a post where you were looking for replacement gears for this motor, did you ever find them?

The motor was too fast "unloaded".....I needed high torque and low speed for pulling power (90% of my riding is off road or in loose sand forest roads). After bench testing using a PS, I ended up building a pack with more AH and lowered voltage. I am very happy with results for my particular application. Considered building a rear 24" fat-wheel but decided to keep my 26".
PS: I never found a source for gears. I ended up buying a 2nd motor to keep on hand 6 months ago.
 
pullin-gs said:
The motor was too fast "unloaded".....I needed high torque and low speed for pulling power (90% of my riding is off road or in loose sand forest roads). After bench testing using a PS, I ended up building a pack with more AH and lowered voltage. I am very happy with results for my particular application. Considered building a rear 24" fat-wheel but decided to keep my 26".
PS: I never found a source for gears. I ended up buying a 2nd motor to keep on hand 6 months ago.

Oh ok, that makes sense for you’re use application. I, on the other hand , would like the speed . One stretch of my commute has no bike lane so I take over the lane but because it’s early morning there is usually a line of cars stuck behind me or trying to pass and get way too close. Last week I was even grazed by someone’s side view mirror. So I want the speed so that I neither slow down traffic nor give the cars any reason to try and pass unsafely ( and illegally) by me. The speed limit is 45 but if I can get to 40ish mph I think that will be good enough.
 
Back
Top