Alltrax 48500 VS Sevcon 4Q Millipak acceleration

[Fastest1]

Please post some pics of the kart! I have been watching a youtuber build a kart with a Montenergy motor and a 150amp controller. He cant get traction under 15mph and stealthy silent.
I almost bought a micro sprint chassis last week. I have a buddy with a pro grade flat track on his farm. He competes on bikes. It would be a hoot and the chassis was spectacular and unused.
The dream isnt over just a little sanity stepped in.


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[userix]

Originally Posted by Sergio

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.

The controller metal case and the large heatsink does get warm accordingly, so I believe the heatsink is doing its job dissipating the heat well. I have properly applied heatsink compound between controller base and heatsink. It's just the timed current cutback feature I find annoying, as Sevcon engineered that in as a controller protection feature.

The maximum current occurs from a dead start right? Because that requires the most torque and current to get the kart moving. With the Sevcon controller, I can see the current instantly starts at 300 motor amps and gradually tapers off once I get up to speed. This is with me flooring the pedal. But seeing how the motor amp current never goes past 300 on the Sevcon, I limited the 48500 to 300A accordingly. But I would assume with motor amp limit the same, the acceleration ramp up should be the same if not better than the Sevcon. The alltrax is not drastically slower in accleration, but it's noticeable. Again, I have the torque curve set pretty much at 100% across the whole graph and the throttle curve is the default line.

Is upping the max motor amp to 350 on the alltrax safe for the ME0909 PMDC?

Originally Posted by E36Racer

You’re asking about a Kart setup? What voltage and what batteries are you running?

Packaging is tough on a kart. I’ve been considering one and aside from my golf cart experience, I’ve 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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I am running a LifePO4 48V 70Ah pack with 300A BMS. Pack was custom built by a battery manufacturer, so I can customize the dimensions for my application. The motor is a motenergy me0909 48V PMDC. Controller is the previously mentioned Sevcon Millipak4Q, but I have been testing it with the Alltrax controller as well 48500. The power on my kart setup it pretty good, while I don't spin wheels off the line, it's fast and fun. I can spin out from a dead start. I have seen 72v builds which are insanely fast.

[userix]

Originally Posted by Fastest1

Please post some pics of the kart! I have been watching a youtuber build a kart with a Montenergy motor and a 150amp controller. He cant get traction under 15mph and stealthy silent.
I almost bought a micro sprint chassis last week. I have a buddy with a pro grade flat track on his farm. He competes on bikes. It would be a hoot and the chassis was spectacular and unused.
The dream isnt over just a little sanity stepped in.


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I still need to fabricate a battery holder, but as is, it's pretty stable. The battery pack (37lb) doesn't budge or shift even with the hardest of acceleration, braking, cornering and spin outs. I know it's probably better to mount the battery on the opposite side for better weight distribution, but the pack doesn't fit well on that side, as it is narrower. Current gearing is 18T up front, 58T rear. I hit top speeds of 43-44mph on flats. Roughly 35mi range on one charge.

The nice thing about the electric kart is I can rip around the neighborhood late at night without disturbing the peace. Perfect way to unwind after a hard day's work.

[E36Racer]

Cool kart. Now I know all of the pitfalls I thought existed, really don’t. I may have to consider building one again.


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[Sergio]

Did You by any chance log the runs with the Alltrax controller to see if there were any alarms, current limit, temperature limit or throttle not reaching 100%?

[Fastest1]

Your making me want to rethink my inaction!


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[userix]

Can battery bms limit maximum current drawn?