QS 273 V3 only reaching top speed of 35mph.

[MangDav]

I have a QS 273 V3 5T motor paired to a Sabvoton SVMC72150 controller and I can only reach top speed of 35mph, 39mph if I'm tucked. From my research when I was buying this motor, 273 V3 3.5T are rated for 70-75mph and going with 5T, I knew I was going lose some top speed but I though it's going to be 15-20mph difference, not half. I would like to be able to go 55mph or around there, I don't need to go any faster. I'm not using flux weakening because I didn't think I will need it but is that the way to be able to go faster than 35mph on a 5T motor?

 

[pwd]

What's the rpm/volt of the motor? Figure that out with your battery voltage then multiply by 0.8 and that will be your rough max rpm if you are feeding it enough current.

And of course; be sure to play with the Grin motor simulator.

 

[liveforphysics]

If your bike is slow and motor runs hot, you probably have a false positive hall and phase pairing.

 

[MangDav]

What's the rpm/volt of the motor? Figure that out with your battery voltage then multiply by 0.8 and that will be your rough max rpm if you are feeding it enough current.

And of course; be sure to play with the Grin motor simulator.

Should I be using the nominal voltage (72) or fully charge voltage (84)?

If your bike is slow and motor runs hot, you probably have a false positive hall and phase pairing.

What do you mean by slow? Like overall slow (accelaration and top speed)? It has the correct accelaration if I had to say, it wheelies from a stand still and gets to 40mph in probably under 3 or 4 seconds, not sure if false hall and phase pairing would affect accelaration or just top speed. I can't tell if the motor runs hot, the hall sensor plug does have a temp sensor coming from the motor but my controller doesn't have it so I have to get a temp display and mount it on my handle bars which I was thinking of doing anyway.

 

[DogDipstick]

Whats your wheel diametyer?

 

[pwd]

...
Should I be using the nominal voltage (72) or fully charge voltage (84)?

Use the nominal voltage; it will give you some headroom etc... and will be closer to real world results.

 

[MangDav]

Whats your wheel diametyer?

19 inch

 

[MangDav]

So I did few tests and changes today;
1. I held the bike up and full throttled, the speed went past 50 before I couldn't hold it up anymore so it's definitely not display or controller limiting the speed to 40.
2. I peformed a hall angle test. From what I read, you don't need to do it if you're using QS hub motor with Sabvoton controller but I did it anyway, it changed hall angle from 55 to 249 and caused the motor to spin backwards which I fixed by changing motor direction setting. I topped out at 41.8mph but since it's only a 1.8mph increase, I'll throw that under margin of error.
3. I tried flux weakening, I set the current to 50A which is the max as I have a locked controller and it did increase the top speed but by only 3mph, I disabled it to make sure I wasn't going down a slight hill or something and it does increase the top speed to 44-45mph which with that increase, it's not even worth it to me to have flux weakening on. Also above 40mph when flux weakening starts, I'm hearing a high pitched beeping sound, with wind noise, it's hard to tell where it's coming from but it sounds like it's coming from the motor which I'm unsure if this is a thing or a side effect of flux weakening. It doesn't make that sound with flux weakening off. Is it even worth it to consider an unlocked controller to be able to use higher flux weakening current?