Powering a 48V cyclone motor rated at 36v-72v @ 80 amp on a 40amp controller

[fabieville]

I had a 36v-72v 3000watt geared cyclone motor rated at 40amps in the past and i was operating it on a 48v 30amp battery pack with a 45A built in BMS and on a average it use to pull around 15-20amps on a flat terrain on full throttle and with the 40amp controller it never past 40amp the most i see it went to was around 35-37amps when climbing very steep hills.

So if i decide to buy the 36-72v 6000watt 80amp rated one and operate it using my 48v 30amp battery with built in 40amp max BMS would my 40amp controller that i have limit the max draw to around 35-40amp and also would i be drawing roughly the same 15-20 amp on a flat terrain at full throttle?

Also would i expect to get the same performance or better than when i was using the smaller 48v 3000watt motor?
Here are the links for both motor:
Top 10 best and Fastest electric dirt bikes Motocross Big Boy ebike DIY Motorized kit Fastest electric dirt bikes Motocross Big Boy ebike DIY Motorized kit Fastest electric dirt bikes Motocross Big Boy ebike DIY Motorized kit world's Fastest electric dir (3K model)

Top 10 best and Fastest electric dirt bikes Motocross Big Boy ebike DIY Motorized kit Fastest electric dirt bikes Motocross Big Boy ebike DIY Motorized kit Fastest electric dirt bikes Motocross Big Boy ebike DIY Motorized kit world's Fastest electric dir (6K model)

I

 

[HumanPerson]

Welcome to the forums

 

[m@Robertson]

I had a Cyclone with a 60a Kelly controller. It peaked at around 60a (I had a wattmeter inline in the battery output line and it kept a peak amp rating until I shut off the bike, so I could check it after each ride).

Your 40a controller, running with a 40a peak BMS, will probably pop your BMS' over-current protection. The reason is your controller has one duration limit for peak output (usually only a few seconds long) and your BMS has another peak duration limit. There's no guarantee the two will match, and it seems the rule is the battery BMS is going to be likely to pop. Thats why the standard advice is to have your continuous battery BMS limit match your controller's peak value. So the battery can handle what the controller feeds it and will never shut down.

If your BMS pops, you will not be able to reset it until you plug into a charger. That means you ride home unpowered.

I've learned this the hard way, btw. I tried a strong pack on a 2wd bike that had IIRC a 10a higher peak limit than I needed 75a peak BMS vs. a 65a peak power requirement from my twin controllers (it was a 2wd bike). It worked fine until I found a long and very gentle incline (not even a hill) that put the motors under strain ever so gently for 30 seconds or so... if I had made it all the way to the top. I didn't.

Also if you have an 80a controller its going to ask for 80a. It doesn't care what the battery wants to limit it to. You have to either get into the controller settings and dial it down yourself (subject to the issues noted above) or you buy a battery with a more badass bms that can handle what the controller is going to ask for.

 

[fabieville]

I had a Cyclone with a 60a Kelly controller. It peaked at around 60a (I had a wattmeter inline in the battery output line and it kept a peak amp rating until I shut off the bike, so I could check it after each ride).

Your 40a controller, running with a 40a peak BMS, will probably pop your BMS' over-current protection. The reason is your controller has one duration limit for peak output (usually only a few seconds long) and your BMS has another peak duration limit. There's no guarantee the two will match, and it seems the rule is the battery BMS is going to be likely to pop. Thats why the standard advice is to have your continuous battery BMS limit match your controller's peak value. So the battery can handle what the controller feeds it and will never shut down.

If your BMS pops, you will not be able to reset it until you plug into a charger. That means you ride home unpowered.

I've learned this the hard way, btw. I tried a strong pack on a 2wd bike that had IIRC a 10a higher peak limit than I needed 75a peak BMS vs. a 65a peak power requirement from my twin controllers (it was a 2wd bike). It worked fine until I found a long and very gentle incline (not even a hill) that put the motors under strain ever so gently for 30 seconds or so... if I had made it all the way to the top. I didn't.

Also if you have an 80a controller its going to ask for 80a. It doesn't care what the battery wants to limit it to. You have to either get into the controller settings and dial it down yourself (subject to the issues noted above) or you buy a battery with a more badass bms that can handle what the controller is going to ask for.

So in essence u r saying if i buy the 80amp rated motor but stick with my 40A controller the controller will only send 40a current to the motor regardless of the stress or terrain?
Also powering the 80amp motor with just 40amp will no way whatsoever cause it to overheat regardless of how much stress i put it under?

And lastly will i still get good enough speed and torque out of it running it off 48v at 40amps max.
BTW the battery bms peak is 100amp and rated amp is 40amp so i think it should be fine.

 

[m@Robertson]

So in essence u r saying if i buy the 80amp rated motor but stick with my 40A controller the controller will only send 40a current to the motor regardless of the stress or terrain?

Yes exactly. The controller deciders what current goes to the motor.

Also powering the 80amp motor with just 40amp will no way whatsoever cause it to overheat regardless of how much stress i put it under?

There's no way to tell that until you run the motor and see, but likely that is a correct assumption. I can tell you my Cyclone overheated if I didn't ride it right. Like all mid drives, power fed to the motor that does not turn into rotation turns into heat, so if you put the bike into too high of a gear, it bogs, generates heat and that can lead to thermal shutdown. The motor would die and I would have to sit roadside for 10 minutes or so before it cooled. I could almost solve the problem by staying off the smallest cog. Almost. When I also covered the motor in heat sinks on the end cap and everywhere else I could, it shucked enough extra heat to make the motor reliable. If I stayed off that smallest cog.

And lastly will i still get good enough speed and torque out of it running it off 48v at 40amps max.

There's no way to tell until you try it. I can say I was not impressed with a 60a controller and a 52v battery. It could work me up to 30-32 mph but it was slow getting there. My weighing about 250 lbs at the time was a major factor in that though. I would say it was no more powerful than a BBSHD, minus the reliability and the refinement you get with an HD for stuff like easy PAS addition, and quality display. That was 2017 though so maybe this has improved. When I did mine the Cyclone was purely an advanced DIY builder's motor and not something you did if you wanted something easy to put together. In particular the motor mounting flexed. You will see a lot of discussion on reinforcing the mount, or doing it all over, at places like Endless Sphere.

BTW the battery bms peak is 100amp and rated amp is 40amp so i think it should be fine.

Don't be surprised if you pop the BMS. 40a continuous output controller on a 40a continuous bms means there is zero fudge in there. You should have at least 10a of excess on the battery side.

 

[fabieville]

so its best to choose the 45amp 4000watt one and try keep my current max to around 30-35amps the most under any given condition?

 

[m@Robertson]

If your battery has a BMS with a continuous power rating of 40a, then thats what I'd do: Limit the controller to 30a peak output. You can try scootching it up to 35a so long as you have a test hill nearby thats so close you don't mind riding back home with no power if your test shows you pushed too close to the upper limit.

 

[fabieville]

The 6000watt motor is rated @ 36v-72v 80A with 80Nm Torque; would it be safe to assume that running the motor @ 48v with 40amp my torque level would be cut in half seeing that my motor is not getting the full 80A?

At the same time the 4000watt one is rated at 36v-72v 45A with 70Nm torque would it be safe to assume that running the motor @ 48V with 40amp my torque level would be close to the 70Nm? Because i am giving it 40amp which is close to its 45A rated. So in essence the 45A rated motor would be giving me better torque performance at the 48v 40amp level vs. the 6000watt one?
The torque is most important to me because i have a lot of hills to climb so i want to choose correctly.






Quote

 

[m@Robertson]

I think the only thing you can say for sure follows general principles: Amps translate to torque, and fewer amps should mean less delivered torque. Dicing it up any more finely than that would be best answered by the manufacturer who knows about any efficiencies gained or lost between the two motor models.