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-   -   Alltrax 48500 VS Sevcon 4Q Millipak acceleration (http://www.buggiesgonewild.com/electric-club-car/153577-alltrax-48500-vs-sevcon-4q-millipak-acceleration.html)

userix 06-03-2019 09:54 PM

Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
I have been testing the alltrax controller and noticed it's slightly slower on acceleration than the sevcon 4q. I have the 48500 set with max amps of 300. Throttle rate is 100% and I maxed the torque curve so that it's 100% across the whole throttle range. The speed curve is the default straight line going 45 degrees up. when launching off the line, the alltrax feels slower accelerating to max speed while the Sevcon acceleration seems to be quicker. I am flooring the pedal off the line with both controllers for the test. Running a 70Ah Lifepo4 48v pack with ME0909 PM DC motor.

The only thing I don't like about the Sevcon 4Q millipak is the "timed current cutback" feature. It will limit the current based on usage, regardless of mosfet temps. So even though the temp of the controller is well below50C, the controller will still limit current by a percentage based on how much current is used during a measured period of time. Does anyone know how to disable this feature?

NoleFan4Ever 06-03-2019 09:57 PM

Re: Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
Be sure on the Alltrax you have Turbo On.

E36Racer 06-04-2019 07:25 AM

Re: Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
If you have the 48500, why are the amps set to only 300? I think stock motors can take 350-400 without burning up.


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Fastest1 06-04-2019 09:51 AM

Re: Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
I am sure they can take 500 for a while ;-)


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Sergio 06-04-2019 09:57 AM

Re: Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
Keep you "Max Battery Amps" at 300 amps to protect your Lithium pack and set the "Max motor Amps" to 400-500 Amps.

userix 06-05-2019 05:07 AM

Re: Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
I thought my motor has a max current of 300A, that's why I limited the motor amps to 300. But it is safe to run the ME0909 over 300A? If I set the battery max to 300A, how will the motor get more than 300A?

Would running a 48300 at its max 300A have better performance than detuning a 48500 down to 300A? Like the acceleration ramp up is weaker on a 48500 set to 300A?

Sergio 06-05-2019 06:57 AM

Re: Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
The controller switches the power to the motor using PWM, so the relation between battery current and motor current is roughly:

Motor Current = Battery Current/Throttle percentage.

If you have the throttle at 50% and the Battery current is 300 amps, the Motor current can be up to 600 amps.

I just googled that Millipack controller and since it is a 4 quadrant motor and You are using a Permanent Magnet motor, it allows you to have "Regen Brake" and not use a reverse contactor or mechanical FNR.

It seems like the Sevcon is a better option for the PM motors.

userix 06-05-2019 07:06 PM

Re: Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
1 Attachment(s)
Quote:

Originally Posted by Sergio (Post 1622151)
The controller switches the power to the motor using PWM, so the relation between battery current and motor current is roughly:

Motor Current = Battery Current/Throttle percentage.

If you have the throttle at 50% and the Battery current is 300 amps, the Motor current can be up to 600 amps.

I just googled that Millipack controller and since it is a 4 quadrant motor and You are using a Permanent Magnet motor, it allows you to have "Regen Brake" and not use a reverse contactor or mechanical FNR.

It seems like the Sevcon is a better option for the PM motors.

I see. but wouldn't that mean at 10% throttle, the motor could be at 3000A?

The millipak is a great controller, except for the annoying "timed current cutback" feature. My motor/controller setup in on a go kart frame, so it's driven aggressively/racing, with constant hard acceleration. I have the controller mounted to a large heatsink and monitor its temperature, which never reaches the high of 50C, but because of my "high" current usage, the controller will cutback current regardless of temperature, which is very annoying because I lose a lot off the line power. I have to power cycle the controller every 5 min or so to reset the timed current cutback. Even with the most aggressive of driving, the controller mosfet temps reaches a high of 37 only, so I know the controller is thermally ok.

Mosfet temp is monitored using Sevcon's calibrator device, which can show current mosfet temp and instantaneous current draw. I don't think there is a way to disable the timed current cutback.

Would running a 48300 at its maximum current power have better performance than running a 48500 limited to 300A?

https://i.ibb.co/GP5RGdt/Untitled.png

Sergio 06-05-2019 10:19 PM

Re: Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
So both the Controller metal body and the external heat-sink have much lower temperature than the internal FET heat-sink temperature?

In that case it does appear to be a Controller issue.

As far as the Alltrax controller You cannot exceed the maximum output rating.

If You are talking about limiting the battery current to 300 amps and keeping the Motor amps at their maximum, the SR48500 with battery amp limited to 300 amps will provide much better performance than the SR48300.

According to the Alltrax specs, the 48300 maximum motor output is 350 amps and the 48500 is 575 amps, if you look closely at the specs You will also notice that maximum output does not occur when the pedal is all the way down.
https://alltraxinc.com/wp-content/up...-B_SPEC-SR.pdf
I don't have any information on the motor, but with any PM motor you need to be careful with high temps as they can loose/weaken their magnetic strength.

E36Racer 06-06-2019 12:05 AM

Re: Alltrax 48500 VS Sevcon 4Q Millipak acceleration
 
Youíre asking about a Kart setup? What voltage and what batteries are you running?

Packaging is tough on a kart. Iíve been considering one and aside from my golf cart experience, Iíve been into RC for decades. Without doing a ton of complicated math, coming up with a killer inexpensive (relatively) electric conversion/solution for a go kart is not an easy answer. Batteries are the problem in a kart frame. To get your rocks off you need at least 55 volts. And a motor much liter than a DC golf cart motor.




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