Bafang G310 geared hub - 11:1 reduction ratio!!!

Greetings from southwest England. Been lurking here months. Some at Grin will recognise me. Anyway, time to pop-up, in my guise of a small-scale e-bike converter-builder (amongst many other things). Decided e-bikes was the way to go in the current climate (-change), as every other person I know wants one but would rather not pay silly prices or risk dubious imports.

I'm on this particular thread because I've just imported a bunch of Bafang G310s, with considerable effort, and am still trying to deal with the fallout. Language misinterpretation issues meant I ended-up with motors with 0.75 m long cables to the Higo-type plug, which I've decided I shorten on a couple (at the motor end), along with fitting an internal thermistor. I've got as far as Grin's disassembly video goes, but would really like to get the stator out of the case too, to get at the wiring behind, before considering whether a non-moulded-on plug might be a better idea.

So, anyone anything to report on getting the stator out of one of these?
 
@trevon... i'm moving to the UK in a few months! if you have any spare motors you'd like to sell off... maybe send me a message!

Anyone have experience setting up a brompton with a front Bafang G310/311?

-Robin
 
Hello !
I just reach the 2700 kms mark with my G310, after 3 months 1/2. Still very happy with this little but powerful motor. I'm using it generally at 600W above 25 kph, and 450W below.
Question for the long range users : what is the duration I can expect from the nylon gears with such use ? Just to know if I should order now a set on ebikes.ca ;)
 
We don't have a lot of collective experience with this motor, unfortunately. Hard to say..
Bafang's geared motors are generally good quality. I think that if you are interested in keeping the motor long term, a spare clutch and set of gears is a pretty smart thing to have in your ebike toolkit. Eventually these parts will fail.
 
Hi,

This morning, after 1h at 750W continuous (@ 40 kph, with external temp around 25 °C), 100m before arriving to destination my G310 encountered a brutal power drop, with a bit of noise. After a few minutes I realized that the motor was very hot, it had clearly overheated. Indeed, using it at 750W for 1h was probably the upper limit ;)

But after a 2h stop, I rode back without problem during 45mn (at 600W), then again, brutal drop in power. I restarted immediately at 450W, and no other trouble during the last 15mn.

--> What could be the explanation of the brutal power failure then correct operation after cooling ?

For sure I was using this motor above its limits, I have reset the max power to 500W.
 
Thanks for chipping in with your experience.
The simulator is accurate yet again. I calculated that the motor would be good for around 700w continuous, as in, 700w for as long as the average ebike battery ( under 1kwhr ). Your real world experience was very close. Although, i imagine it is a bit hot in your area this time of year, so maybe during cooler months, 750w for an hour is no problem.. :thumb:

That brutal power drop happens when the copper in the stator gets so hot that it conducts worse and worse and exponentially gets hotter until it loses ~50% of it's power. You are lucky you made it home without melting the plastic gears inside.

You may have demagnetized your motor a little bit after it becoming so hot that the performance dropped that far.. i did that with a MAC geared motor a very long time ago.. but i kept using the motor for years after i almost melted it.. i just dropped the power a little bit and she survived.
 
Thanks neptronix.
I have a 1 kWh battery, and I remember having ridden it @ 700W for 45mn continuously in May (the temperature was cooler) without troubles.
So yes 750W continuous during one hour is too much for this motor, I think I will stick to 600-650W now.
Do you think it worths replacing the core (https://www.ebikes.ca/shop/electric-bicycle-parts/motor-hardware/gears/mg31xcore.html) ?
 
Oh wow, it's cool that you can replace the core for such a low price. :)

It's up to you whether you replace it or just live with it like it is. Maybe you are a few aerodynamics changes away from maintaining your desired top speed in the summer though.. a tail fairing or small fairing on the handlebars may allow you to drop 50-100w from the continuous load, and the motor will survive it forever..

Big batteries complicate what is a 'continuous' rating of a motor, for sure.. :)
 
I am also looking at the GMAC, but the cost (8-900 dollars with the Phaserunner, plus french VAT and transport) makes me think about it twice.
Good advices concerning the aerodynamic changes :)
 
So now I'm thinking about modifying my Krampus in order to be able to ride continuously (ie. at least one hour, even in summer) @ 8-900W and 45 kph (on flat terrain).

I have 2 options :
- installing a more powerfull rear motor. See my post here : https://endless-sphere.com/forums/viewtopic.php?f=3&t=102098.
- keeping the G310 rear and installing a G311 on the front wheel.

About the second option, do you think it's realistic ?
Running at 900W will mean 450W on each motor which is plenty in the G31x range of continuous operation. And I would have a nice 2x2 ebike 8)
My front and rear wheel/tires are exactlly the same (rims Ryde Andra 40/29", tires Surly ET 29x2.5).
I won't need to operate at more than 20A total (as I have a 52V battery), so my current Grininfineon 20A controller can theoritically do the job.

Is it possible to keep only one controller/one Cycle Analyst, and connect the G311 front motor and G310 rear motor simultaneously to the entry plug of the controller with a Z910 jack in parallel, and theoritically receiving/sending the same signal/power from/to both motors.
If yes, I haven't found that kind of jack for sell, do you think it would possible to build one ?
 
Look into putting oil into the G310 to boost its dissipation. Should be good for 1000W+.
 
Jil said:
Is it possible to keep only one controller/one Cycle Analyst, and connect the G311 front motor and G310 rear motor simultaneously to the entry plug of the controller with a Z910 jack in parallel, and theoritically receiving/sending the same signal/power from/to both motors.
Click to expand...
No.

Each brushless motor requires it's own controller.

The only way you can run multiple brushless motors off a single controller is if their rotors/stators are physically locked together in-phase, whcih you can't do if they're in different wheels.
 
If you need 1000W, just buy a MAC motor. That's all you'll need - and it'll do a bit more than 1000w i hear.
 
1N4001 said:
Look into putting oil into the G310 to boost its dissipation. Should be good for 1000W+.
Click to expand...
That’s also an option, I’ve just read the thread about cooling, it seems very efficient.
Does the G310 need extra-sealing before putting oil inside it ?
What’s the best oil to use ? Classic motor oil, silicone oil, vegetable oil...
 
Jil said:
1N4001 said:
Look into putting oil into the G310 to boost its dissipation. Should be good for 1000W+.
Click to expand...
That’s also an option, I’ve just read the thread about cooling, it seems very efficient.
Does the G310 need extra-sealing before putting oil inside it ?
What’s the best oil to use ? Classic motor oil, silicone oil, vegetable oil...
Click to expand...

The G310's seals are pretty good to begin with, but there's still the possibility that a drop will leak on occasion. This is unavoidable.

ATF is known to attack seals or wire insulation. Never ever use vegetable oil in machines, it will go bad. Silicone oil is what I suggest, it's chemically inert, transports heat well, won't go bad and is thin enough to not add much drag.

john61ct said:
1N4001 said:
And hear it you will [emoji38]
Click to expand...

Are you saying it's noisy?
Click to expand...

Yes, the MACs are among the noisiest geared hubs.
 
Thanks, let’s go for silicone oil :thumb:
 
Jil said:
This morning, after 1h at 750W continuous (@ 40 kph, with external temp around 25 °C), 100m before arriving to destination my G310 encountered a brutal power drop, with a bit of noise. After a few minutes I realized that the motor was very hot, it had clearly overheated. Indeed, using it at 750W for 1h was probably the upper limit ;)
Click to expand...
Hi,
This morning, same thing happened, after 20km @ 800 watts on flat land. The weather was cold (around 10 deg C). I have been able to restart almost immediately at lower power (400 watts).

The G310 is definitely not done for use above 600-700 watts.

Hopefully I should receive this week the Gmac ;)
 
I just built a little throttle cutoff harness for over-volted/watted motors that uses a mini 5v thermostat board, that cuts off the throttle when the motor internals hit 120 degrees Celsius.

LM YN Digital Thermostat Module DC 5V -10℃ to +210℃ Electronic Temperature Control Module Switch Waterproof Sensor Probe Dual LED Display Red+Green

https://www.amazon.com/gp/product/B01M1J64LQ/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

The board works off 5v and can use the VCC of the throttle wire to power the board. Then the board relay cuts off power to the throttle when over 120 degrees. Works like a charm.

I made a throttle cable harness that can be easily removed if the board dies on a ride.

The beauty about this is that you can use the throttle wires to both power the board and cut-off the throttle, making it a somewhat clean setup. I prefer this over techniques that cut off power to the motor or controller.

You have to open the motor, epoxy the thermostat to the windings, and poke the wire out of the existing hall/phase hole. Next I'm going to install the board into a clear plastic case to semi-waterproof it.

81uwi8IcXNL._SL1500_.jpg
 
For a hub motor you could loose power from any number of things: low batteries, loose cables,etc.

Use this technique your own discretion. I'm fine with it. I generally know when I'm pushing my small motors too hard.

Use a CA instead if you want power roll-back to prevent overheating. I don't use a CA and was looking at doing something simple.
 
zukster, please take pictures of how you installed the temp probe and how you routed the wires out of the motor. I tried and couldn't find a route to get it out.
 
I can post the circuit but I'm not opening up the motor again until it needs servicing. If you do a thorough Google serach, you can find a few examples of other people epoxying thermosters to motor windings. I think automotive silicone would probably work too.

You need to get the wire out where the phase/hall wires come out. If you can't do that, it won't work.
 
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