QSMotor 2000w vs. 3000w range same speed?

[Mavec]


Recently the man who sold me my electric motorcycle upgraded my batteries from 72v20a lead acid to CATL 72v100a lithium ternary batteries. Very happy indeed. But I am thinking of going a step forward and upgrading the QS Motor 2000w hub motor to a QS Motor 3000w hub motor for sometimes faster speed and acceleration. The current max speed I reached in ideal conditions tracked by GPS is 83.7 kmph, and usually I cannot push it over 75 kpmh. He says a 3000w motor will increase the maximum speed to around 100 kpmh.

On one battery charge on my original 2000w motor I was able to go 181.7 kilometers in setting 3 (the setting that consumes the most energy) and 246.5 kilometers on setting 2 (mid setting) before the BMS stopped the motor.

Now, I’m not a very technical person and we speak different languages but communicate through Google Translate (he’s Chinese, we live in Laos), so some things get lost in translation.

I am trying to understand that if I go the same speed with the 3000w motor as the original 2000w motor, will the same amount of battery be used/will I have the same range per charge? For example, if hypothetically I were to maintain a continuous speed of 60 or 70 kpmh with each motor, hypothetically under same driving conditions and the only difference being the motor, would I have the same range with the new 3000w motor? If not, would I lose a lot of range? I do understand that in faster speeds I will lose range, but am confused about this point.

Thank you for helping out someone who has a hard time grasping some of these concepts.

 

[john61ct]

Of course with different motors the power curves are different, so the energy efficiency cannot be exactly the same.

And you have a heavier motor and battery, so a little efficiency lost there.

But I doubt if you are **truly** strict about not going any faster the difference will be that significant.

However, in real life, you **will** tend to go faster, unless you have an electronic limiter set up.

Therefore you will need to be careful, faster your average speed, **much** less efficient.

 

[Mavec]

What do you mean truly strict about not going faster?

 

[ZeroEm]

If the new motor was limited to same acceleration and top end the range would be close to the same. If range is important then keep the current motor. The higher watt motor will used more watts because we like using the power and the range will be less. I battle the range vs power every time I ride. I have a power limiting switch and low is all I need but it does not stay there.

 

[john61ct]

What do you mean truly strict about not going faster?

A limit enforced by a CAv3 or your controller is going to be more effective than assuming you a normal human will keep speed to the same limit as with the old motor.

That is why you're likely to be lots less efficient, not technical reasons but failure of self control.

Like leaving candy around the house and expecting kids to exercise self control.

 

[j bjork]

Is your motor overheating? In that case you will probably get more range with a bigger motor, becase of better efficency.
To get more power I think a change of controller will make more difference if you are not absolutly saturating the one you have.

 

[Voltron]

The wattage is supposedly safe limit of how much you can put into the motor... So if your controller isn't putting out enough power to make you worry about melting your motor already, then changing motors won't do much except run cooler. It's not like the controller is limiting the power because it knows it's hooked up to a lower wattage motor, unless it has a heat sensor that's rolling back the power... So you shouldn't notice some large difference... Just cooler running.
The top speed is mostly from the voltage, so unless the you know for a fact it has a different turn count on the windings, which make a motor go faster or slower for the same voltage, you could end up with the same top speed.
Either way, it won't change the range much... Unless it's so much more fun to drive that you start drag racing cars.... That's what cuts into ones range .

 

[DAND214]

mavec wrote:
Recently the man who sold me my electric motorcycle upgraded my batteries from 72v20a lead acid to CATL 72v100a lithium ternary batteries.

It was a 20ah lead battery and now a 100ah Catl battery, you should see a big increase in range and maybe some top end since the catl should have a higher discharge rate. 100ah battery is a big battery but maybe no bigger than the lead.

As others ask is, does the 2000w motor over heat? If not you might adjust the controller to a higher discharge rate for more speed. it might or may not increase the speed.

Dan

 

[john61ct]

Once that 3000W is in place, then the feeling of power has a lot to do with accelerating, zipping off the line and up hills faster.

Increasing voltage to crank up the top speed is not as fraught an upgrade

but that's where energy efficiency really goes out the window

 

[John in CR]

If you decide to change motors, then talk to QS directly to explain what you want so you end up with the right winding of the motor you choose.

You might consider upgrading your controller instead. A 24fet Nucular controller will give you both greater efficiency and greater top speed. On top of that you'll get better throttle control that you can tune to your liking and well as smooth as silk variable regen braking. Be warned though there is currently a 5month backlog for the 24fet controllers. The bigger motor will require a different controller to really take advantage of the extra capabilities.

Since the bike started as a lead laden pig (ie as cheap a battery as possible), it's highly unlikely that it has a top quality controller, so stepping up to a Nuc would be a huge upgrade to your riding experience, a purchase that I assure you won't regret. The only drawback is that long wait. If you don't agree once you get it going, I'd be more than happy to buy it from you for almost full price.

 

[Mavec]

mavec wrote:
Recently the man who sold me my electric motorcycle upgraded my batteries from 72v20a lead acid to CATL 72v100a lithium ternary batteries.

It was a 20ah lead battery and now a 100ah Catl battery, you should see a big increase in range and maybe some top end since the catl should have a higher discharge rate. 100ah battery is a big battery but maybe no bigger than the lead.

As others ask is, does the 2000w motor over heat? If not you might adjust the controller to a higher discharge rate for more speed. it might or may not increase the speed.

Hi Dan,

Yes, with the CATL 72v100AH batteries it is 5 times what it was with the lead acid, very impressive.

The Chinese technician who installed the new battery says my 2000w motor will overheat if we increase the speed further. So I wonder what to do in order to reach about 100-110 kpmh and not reduce range significantly from what it is with the CATL batteries.

 

[John in CR]

The Chinese technician who installed the new battery says my 2000w motor will overheat if we increase the speed further. So I wonder what to do in order to reach about 100-110 kpmh and not reduce range significantly from what it is with the CATL batteries.

If you're talking about increasing cruising speed that much without impacting range significantly, then no that's impossible without a significant range reduction, because wind resistance increases geometrically with speed as does the power required at the wheel. Even a motor change isn't going to significantly increase cruising speed without significantly impacting range without a big increase in motor efficiency. If you're talking about increasing top speed that you use in short spurts, but cruise usually at your current speed, then you can get similar range as now. Practically speeding you have a nice big battery now, so for running around town you should be able to ride with greater performance without range anxiety, and then on longer trips consciously ride in a more conservative manner and get even more range than you currently do. You really need an onboard system that measures consumption, so you know the exact status of your battery as how much energy you are using. I have a 21s55ah pack on a bike with a top speed of 120-130kph depending on voltage and riding position, and I use it daily mostly around town riding aggressively and slaughtering all but big motorcycles. Then for long rides I ride in a manner to conserve juice and stretch range out well past 100km.

Regarding overheating, what the tech said may or may not be true. Motor temps are often dictated more by how your ride than how fast you ride. If your motor has a temp sensor, then the more advanced controllers can self limit based on motor temp to prevent them from getting too hot. In addition motors can be modified for better cooling, and even something as simple as deflecting more air flow at the side covers can have a significant impact on motor temps.

In addition, ambient temps and terrain play huge roles in motor operating temps. For a couple of years I was commuting 25km each way. On the way in I used 50% more energy and the motor ran at significantly higher temps, despite the fact that the return home was at significantly higher speed. That's because the route to work included a net increase in elevation of 300m with usually a slight headwind, more hard launches showing off from stoplights, and generally warmer temps.

Thermal management allows us to push hubmotors far beyond their factory designed limits. That's how one of my bikes has a top speed of over 180kph, yet that motor (the same out of production 6phase motor I run on several of my bikes) actually runs cooler than on my other bikes. Of course that motor is modified for improved cooling to be able to run at those speeds, and in a manner as aggressive and fast as my battery capacity will allow.

 

[larsb]

You need to describe your whole system to answer the original question

What is your wheel size?
What voltage battery?
What is the current limit for the new battery?
What is the current limit on the BMS?
What controller do you have now? Name or pictures of all markings..
Can you program controller?

Then we can do more than guesswork what would be possible or even the best option.
:wink: