100v speeds way off vesc

[mt5000]

I'm currently running a Flipsky 75100 Pro V2 controller. I know it's not officially rated for 100V, but it's been handling it surprisingly well so far.

A friend mentioned that with 100V and even just 100A, I should be hitting around 70 mph. However, I'm only seeing speeds of about 47–50 mph without using field weakening. My flux linkage is set at 25 mWb, and I'm wondering if lowering it might help.

My current settings are 112A line current and 120A phase current—I'm being fairly conservative. Could my relatively low current limits be holding me back, or is it more likely that the hub motor itself is the limiting factor?

 

[Chalo]

When I use my favorite power and speed calculator, assuming 10kW input and 75% gross efficiency to the wheel at top speed, 325 lbs bike + rider weight, low elevation, tough bicycle tires... I get 55 mph. These are relatively optimistic assumptions.

I think you're power limited, not performance limited.

 

[mt5000]

When I use my favorite power and speed calculator, assuming 10kW input and 75% gross efficiency to the wheel at top speed, 325 lbs bike + rider weight, low elevation, tough bicycle tires... I get 55 mph. These are relatively optimistic assumptions.

I think you're power limited, not performance limited.

Gotcha, bike is around 100 and I’m 175, battery can be raised in amps upwards to 200 max, phase can be set up to 300 so would that help raw performance. I kinda figured bc I tried telling him no matter what hubs are very inefficient and take alot of power to go really fast. He had me second guessing my build but it still seems to check out w our field weakening involved

 

[j bjork]

What do your logs say? How much voltage sag? Is the current tapering off at higher speed? If the voltage sag isn't too bad and the you are not loosing power a beefier controller would help. You have already maxed out the one you have, you could turn up more, but it will probably blow fets sooner rather than later.

 

[pwd]

What is your wheel size, gear ratio (if not direct drive) and motor?

 

[mt5000]

What is your wheel size, gear ratio (if not direct drive) and motor?

Direct drive, 20 inch tyres

 

[mt5000]

Direct drive, 20 inch tyres

Motor is from dxwgz on alibaba 72v rated direct drive hub

 

[mt5000]

What do your logs say? How much voltage sag? Is the current tapering off at higher speed? If the voltage sag isn't too bad and the you are not loosing power a beefier controller would help. You have already maxed out the one you have, you could turn up more, but it will probably blow fets sooner rather than later.

So voltage sag isn’t rlly bad at what I was pulling then, however I have not tested the new tune I put amps at 145 and 300 phase amps to test waiting on brakes to arrive today to be able to stop at high speeds. Also added a bit of field weakening without field weakening noticed my erpm was capped at 25k rpm, high speeds I did see phase drop drastically assuming emf is being hit I think the motor is to blame in my build

 

[scianiac]

Yeah if the motor doesn't have a high enough Kv it just won't go any faster without more voltage or a larger wheel. I mean field weakening will do a little but hub motors don't gain massively from that (and that's really asking to nuke that controller), over modulation may also give you slightly more but still small changes.

 

[mt5000]

Yeah if the motor doesn't have a high enough Kv it just won't go any faster without more voltage or a larger wheel. I mean field weakening will do a little but hub motors don't gain massively from that (and that's really asking to nuke that controller), over modulation may also give you slightly more but still small changes.

That’s what I thought

 

[chuyskywalker]

That’s what I thought

Easiest way to tell is to just run the motor in the air. With "no load", you'll need barely any amps and the motor will hit max RPM per volt very quickly. As noted, FW can get your a few more MPH, but it's not free (costs lots of battery amps, thus range + wear and tear on the components + extra heat). I generally advise people to not utilize FW because, while it's neat that we've got the tech to do that, it really is a costly patch over a system the isn't designed to the real specs you want.

Sadly, there's no simple fix for the KV of your motor not being what you want.

 

[mt5000]

Easiest way to tell is to just run the motor in the air. With "no load", you'll need barely any amps and the motor will hit max RPM per volt very quickly. As noted, FW can get your a few more MPH, but it's not free (costs lots of battery amps, thus range + wear and tear on the components + extra heat). I generally advise people to not utilize FW because, while it's neat that we've got the tech to do that, it really is a costly patch over a system the isn't designed to the real specs you want.

Sadly, there's no simple fix for the KV of your motor not being what you want.

Yeah I know did that on my stock was fun, chances are I’ll buy a new hub