Why no high rpm boost for Phantom ESC?

[stevo585]

So I understand that the Phantom ESC's DC motor runs at a constant speed therefore it "falls on its face" at high rpms (losses boost pressure). So why can't the system ramp up the amperage at higher rpm to increase the compressor speed and give constant boost pressure like a traditional turbo system.

This is the biggest downside to the system for me. Also that there is no upgrade path you can just up the boost...right?

[stevo585]

Moderators please move to FI section.

[xwd]

I don't have the dynos in front me but I thought it still showed gains all the way to redline and it wasn't until about 6000RPM it started to drop off?

I think it would really just be a tradeoff of batteries, runtime, longevity of the motor/turbine, size of the turbine, cost, etc. You probably get diminishing returns by putting in a system which could sustain the levels at higher RPM.

[bfrank1972]

Search the Phantom thread here in FI section - basically it can only run a couple PSI at high RPM because of battery (and perhaps motor) limitations. Possible to run more? Yes, but it will cost more - this system is all about compromise, big torque bang for not much buck.

[Target70]

the reason it can't ramp up amperage later is because it is using the maximum amount potential it has from the start.

[industrial]

Originally Posted by stevo585

So I understand that the Phantom ESC's DC motor runs at a constant speed therefore it "falls on its face" at high rpms (losses boost pressure). So why can't the system ramp up the amperage at higher rpm to increase the compressor speed and give constant boost pressure like a traditional turbo system.

This is the biggest downside to the system for me. Also that there is no upgrade path you can just up the boost...right?

You are asking the wrong question. The way this system works, you would need to scale back boost at lower rpms to achieve the effect you desire (no boost taper). To maintain a steady 5psi of boost throughout the rev range, a properly designed system would probably be able to provide 15psi of boost at lower rpms and would need to be scaled back. Such a system would require a much larger battery pack, charging equipment and beefier motor. I imagine this would not be cost effective past a certain point. The designer of the current system weighed these options and picked the best compromise he could engineer. It's a cool system. You need to radically redesign the system to do what you want.

[Luckrider]

To further comment on what @industrial is saying, you need to first think about how an engine works. In each breath, or combustion cycle, the motor draws in a certain amount of air. The higher the RPM, the more combustion cycles and the more air the motor consumes. The ESC tapers off because it puts out a fixed amount of air and the motor literally consumers the pressure down to lower boost levels.

[Sonolin]

I think its a decent boost. I'd love to ride in one and think it would make for a cool daily, however I can't see this working at the track well.

From the youtube pulls it looks really cool, and honestly the feel of torque at low RPM's is really great and I think first impressions of this unit will be very positive.

Just speculation though

[Luckrider]

Originally Posted by Sonolin

I think its a decent boost. I'd love to ride in one and think it would make for a cool daily, however I can't see this working at the track well.

From the youtube pulls it looks really cool, and honestly the feel of torque at low RPM's is really great and I think first impressions of this unit will be very positive.

Just speculation though

I think with a dual pack setup it would track better than you expect, but that is just my speculation. I kinda hope to see an ESC/SC combo.

[stevo585]

Don't get me wrong I'm a fan of the system.

I just think it needs a 36V higher speed motor. So for example run 24V until a certain rpm say 6k then jump to 36V. I may just redesign the system myself. I have several electrical engineers I work with (I'm a Mechanical Eng). We certainly can come up with something.

Makes the system more complex but I like a challenge.

[Luckrider]

Originally Posted by stevo585

Don't get me wrong I'm a fan of the system.

I just think it needs a 36V higher speed motor. So for example run 24V until a certain rpm say 6k then jump to 36V. I may just redesign the system myself. I have several electrical engineers I work with (I'm a Mechanical Eng). We certainly can come up with something.

Makes the system more complex but I like a challenge.

6 Battery setup? 2x 3 battery series wired in parallel. I thought about this until I heard about the high voltage shutdown in the wiring employed by the regular harness that comes with the PhantomCharger.

[stevo585]

I would just do a 3X but yeah I read that too probably to protect the DC motor.

That's really what I'm wondering what is the limiting piece in the ESC? And it must be the DC motor. If the controller is capable of 5k watts then that means the system is able to pull ~178 A @ 28V. Is it really pulling that many amps from the batteries? Doubtful but could be close