Can MAC 8T take 2000W+?
- Thread starter brucejun
- Start date
PRW
100 kW
have a play with this..... https://ebikes.ca/tools/simulator.html?motor=MMAC8T&batt=B5216_GA&cont=C40
I melted the gears on my oldschool 2011 0.5mm lam 8T motor in 5 minutes at 4kW.
Time to melt should be longer on new macs due to the much higher efficiency from 0.27-0.35mm lams installed in them.
Let the heat coming off the side cover be your guide if it doesn't have a temp sensor. Frequent checks with the hand are useful. If it feels hot on the outside, it's too hot. If you can't stand to have your hand on it longer than 10 seconds, you've demagnetized it at the very least.
I abused that 4kw ran MAC at 2600W for long periods of time... but not on severe hills.
The MAC is a sleeper and will surprise you with how much power it takes. Very underrated motor.
Time to melt should be longer on new macs due to the much higher efficiency from 0.27-0.35mm lams installed in them.
Let the heat coming off the side cover be your guide if it doesn't have a temp sensor. Frequent checks with the hand are useful. If it feels hot on the outside, it's too hot. If you can't stand to have your hand on it longer than 10 seconds, you've demagnetized it at the very least.
I abused that 4kw ran MAC at 2600W for long periods of time... but not on severe hills.
The MAC is a sleeper and will surprise you with how much power it takes. Very underrated motor.
Uphill is the worst scenario for any hub motor, because low RPM correlates with low efficiency. Continuous power handling needs to be assessed on flat ground for a neutral comparison. On the simulator, increase the voltage to do this.
Since the motor won't get close to pulling 2000W on flat ground (only 1100W), the only other parameter that the simulator has available is to apply headwind, but even with a 30mph headwind, that only gets the motor up to 1600W.neptronix said:
https://ebikes.ca/tools/simulator.html?motor=MMAC8T&batt=B5216_GA&cont=cust_60_150_0.03_V&hp=0&grade=0&axis=mph&wind=0&cont_b=cust_60_150_0.03_V&motor_b=MMAC8T&batt_b=B5216_GA&hp_b=0&bopen=true&wind_b=-30
But if you did have a headwind that creates 2000W of load, then I believe the same issues would be encountered as if the load was from climbing, to the motor at least (other than trying not to be blown over by a 50mph headwind, and the additional air cooling for the motor).
E-HP said:
Increase loading by slowing motor rpm affects the efficiency and increases phase amps that makes the motor heat up faster. Also decreasing speed affects the cooling negatively. Of course increasing loading desrcibes that specific situation correctly.
Now when we are talking about ASi 800 we should consider also field weakening that is not incorporated within the motor simulator at least yet. That will extend the power-speed curve starting from the excisting max power value towards higher rpms. This will drop the efficiency a bit though.
But lets consider this case without field weakening feature. The question itself is broad and giving on answer might be misleading in context of real life settings but giving couple of examples might enlighten this so.
First level ground full 52v battery 40A (100A phase) controller and 26" wheel is max 2070w configuration. Motor can withstand this maximum of 12 minutes at 373 rpm (29.1 mph).
https://ebikes.ca/tools/simulator.html?motor=MMAC8T&batt=cust_58_0.15_18&cont=cust_40_100_0.03_V&hp=0&grade=0&axis=mph&wheel=26i
When we load the motor in any way to decrease rpm but still pulling 2000w the time for overheating decreases. At minimum rpm where 2000w draw can happen is 118 rpm (9.2 mph). Motor will overheat in 2.3 minutes.
https://ebikes.ca/tools/simulator.html?motor=MMAC8T&batt=cust_58_0.15_18&cont=cust_40_100_0.03_V&hp=0&grade=0&axis=mph&wheel=26i
Also we can look this the other way round. You can pull 1700w forever and never overheat the motor if your rpm is >408 (31.8 mph).
https://ebikes.ca/tools/simulator.html?motor=MMAC8T&batt=cust_58_0.15_18&cont=cust_40_100_0.03_V&hp=0&grade=0&axis=mph&wheel=26i
Then at low rpms where the phase amps (and so torque) are maxed you will overheat the motor quite instantly with 100A phase current.
https://ebikes.ca/tools/simulator.html?motor=MMAC8T&batt=cust_58_0.15_18&cont=cust_40_100_0.03_V&hp=0&grade=0&axis=mph&wheel=26i&throt=100
Considering safe phase amps that will not overheat the motor in any imaginable slow speed settings will require us to go as low as 30A. In real world we dont want to limit our phase amps to 30 but ride wisely and possibly monitor motor temp.
https://ebikes.ca/tools/simulator.html?motor=MMAC8T&batt=cust_58_0.15_18&cont=cust_30_30_0.03_V&hp=0&grade=0&axis=mph&wheel=26i&throt=100
1942W actually, since the question is if the motor can handle 2000W, not how much is being pulled from the battery at any given time. I'm not sure I buy into moving the slider as being the "right" way to simulate 2000W of continuous load, since the slider shows the outputs at that speed(assuming the throttle box isn't checked) for accelerating at full throttle, so not continuous. While adding a grade or wind resistance simulates a continuous load, and the motor itself doesn't know it's due to a hill or wind.TuomasK said:
The question was can the motor handle 2000w. The 2600w in your example IS the power the motor is handling. The 2000w is the power after motor efficiency losses. It takes in 2600w and converts 2000w (1942w) of it into mechanical work.E-HP said:
The motor can be fed 2000w in multiple combinations of volts and amps depending on rpm. For the motor they are not equals stressful.
Loadind the motor at low rpm is the worst situation and in case of 8t mac 400w can fry it.
The hill and wind resistance add a high load at a lower RPM which is only a good assessment of continuous power capabilities if you are in that scenario. In this scenario, the lower rpm leads to lower continuous handling capabilities.
Flat ground on high voltage will tell you a lot more about continuous power handling. This is the condition you'll be operating it at.
The motor is absolutely capable of 2000W+ for short periods of time. I've proven it a decade ago. The ebikes.ca simulator showed it was capable of this long ago. So did Paul at em3ev.
And again, my motor was significantly less efficient than the modern ones with 0.35mm and 0.27mm lams.
Go get one if the simulator verifies that the motor fits your use case. I've found that the simulator matches the real world so closely that i've relied upon it for many successful builds. Real world experience can be extrapolated from dyno sheets too. That is how i discovered the leaf 1.5kw, MAC, and other motors which were previously seen as subpar due to poor marketing.
Flat ground on high voltage will tell you a lot more about continuous power handling. This is the condition you'll be operating it at.
The motor is absolutely capable of 2000W+ for short periods of time. I've proven it a decade ago. The ebikes.ca simulator showed it was capable of this long ago. So did Paul at em3ev.
And again, my motor was significantly less efficient than the modern ones with 0.35mm and 0.27mm lams.
Go get one if the simulator verifies that the motor fits your use case. I've found that the simulator matches the real world so closely that i've relied upon it for many successful builds. Real world experience can be extrapolated from dyno sheets too. That is how i discovered the leaf 1.5kw, MAC, and other motors which were previously seen as subpar due to poor marketing.
neptronix said:
The problem is that the OP has specified the voltage as 52V, so it seems like that's a fixed input as far as the question goes. Then on flat ground, the motor will never pull 2000W unless under acceleration, based on the simulator.
Perhaps we should wait for OP to reply, ha.
The ASI controller brings the options to do flux weakening and could run 2000w continuous on the lower voltage, just like my oldschool infineon clones. That's how i managed long periods of >2000w on an 8T winding MAC on 15S lipo... at the cost of some efficiency. :thumb:
The ASI controller brings the options to do flux weakening and could run 2000w continuous on the lower voltage, just like my oldschool infineon clones. That's how i managed long periods of >2000w on an 8T winding MAC on 15S lipo... at the cost of some efficiency. :thumb:
neptronix said:
Ya, I think with flux weakening, it you could probably get the motor to pull 2000W.
Hey, on that subject, what kind of effect on no load speed do you see with it on or off. With my hub, I get about 38mph no load when off, and 56mph no load when on, 20S running at about 3/4 charge. Of course no where near that jump when loaded. Wondering if that sounds typical. Haven't messed with the controller settings though since I rarely use it.
