QSmotor 8kw, how big battery needed?

V

vaikoh

10 µW
Joined
Oct 5, 2020
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5
Hey.

I'm thinking of starting a cafe racer build with 8kw qsmotor.
I know it depends on many things but very roughly speaking, how big of a battery would I need to get 100 mile range for this bike? Is it even possible?

I was thinking of 72V 70Ah battery.
https://www.aliexpress.com/item/32915614337.html?spm=a2g0o.productlist.0.0.22624510STmD3S&algo_pvid=54f08492-b188-4234-8fca-52e7a8241347&algo_expid=54f08492-b188-4234-8fca-52e7a8241347-2&btsid=0bb0622f16019889249467884e191b&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

What do you guys think of this?
 
Short answer: yeah maybe 70Ah would be a good start, probably wouldn't get you 100 miles on a full sized motorcycle because they are heavy. Here's a DIY build to show some of the work involved with a smaller motorcycle https://endless-sphere.com/forums/viewtopic.php?t=105659#p1546035


Longer answer:
The replies you are about to receive will ask for speed, weight, acceleration and other riding characteristics. Those are things you'll have to decide before this forum can give you meaningful support. You can get 100 miles per charge if that is the only thing you care about and putt along at 7mph downhill.

If you are starting from scratch, I'd look at some specifications for commercial bikes (zero motorcycles) and consider they have an engineering team to achieve their goals. Highway speeds, triple digit range and reliability are not going to be cheap but with enough money and energy, you could get there after while.
 
Thanks for the answer. And yes, I am starting from scratch.

My priorities are as follows:

1. Range - at least 100 miles (+ reliability of being able to cover that distance in one go)
2. Highway speed - 65mph is enough
3. Acceleration

Do you think I can get to my goals with theoretical planning, or would I have to order the batteries, and change when I realise they don't match my goals?
 
Give me a few weeks and I will let you know.

I have a V4 QSmotors 8,000watt hub with an ASI BAC 8000 driving it. I bought 11 Nissan Leaf Cells and should have the battery together soon. I believe my pack will be 5KWh. I am guessing/hoping to get 100 miles and a top speed of 70mph or so. I expect to get 100 mile range if I go easy and 50ish mile range if I accelerate hard and stay over 50 MPH.

Good Luck.
 
I started thinking about what you all said.

8kw motor with 70ah battery would give me either highway speed or 100mile range but not both at the same time.
My question is, what would I need to change to get closer to having both? Would having a bigger battery (100ah, 120ah etc) do it or would I need a more powerful motor also (for example 10kw).
 
If you get highway speed from the motor and controller, then more range would come from a bigger battery pack. I don't think going up on the motor power or controller will help your range much. The trick will be cramming a big enough pack with enough energy density to give you the range you want. (and understanding how much you need).
 
vaikoh said:
I started thinking about what you all said.

8kw motor with 70ah battery would give me either highway speed or 100mile range but not both at the same time.
My question is, what would I need to change to get closer to having both? Would having a bigger battery (100ah, 120ah etc) do it or would I need a more powerful motor also (for example 10kw).
Click to expand...

100Ah@72V is 7.2kWh. Same kWh as the base Zero motorcycle. The Zero goes less than 50 miles at highway speeds. You probably need closer to 14kWh to do 100 miles at highway speeds. That’s a big-ass battery. Call me crazy, but that’s a lot to bite off for a first build.
 
roadpupp said:
Give me a few weeks and I will let you know.

I have a V4 QSmotors 8,000watt hub with an ASI BAC 8000 driving it. I bought 11 Nissan Leaf Cells and should have the battery together soon. I believe my pack will be 5KWh. I am guessing/hoping to get 100 miles and a top speed of 70mph or so. I expect to get 100 mile range if I go easy and 50ish mile range if I accelerate hard and stay over 50 MPH.

Good Luck.
Click to expand...

i would be very surprised if you get a 100 miles from it.

for comparission. the Silence S01 motorscooter has a 7kw hub motor and a 5kwh battery. its range is about 100km or about 62 miles.
 
I have installed 7,4kwh battery in my scooter. 5kW QS Motor and Sabvoton SVMC72150

Behind a truck on the motorway ( 90km/h / 55mph) I get near the 100mile.
Without the truck and full speed (max speed is 103km/h 64mph) I get around 60 miles
During normal driving I get 60-80miles.
 
dominik h said:
I have installed 7,4kwh battery in my scooter. 5kW QS Motor and Sabvoton SVMC72150

Behind a truck on the motorway ( 90km/h / 55mph) I get near the 100mile.
Without the truck and full speed (max speed is 103km/h 64mph) I get around 60 miles
During normal driving I get 60-80miles.
Click to expand...

what QS motor are you running? sounds interesting.
 
QS60V5000W 10 years old, Battery is 21S5P (total 100Ah) Li-NMC Cenat Power pouch cell, rated continous discharge 8C charge 5C
Without weakening field and full battery (87V) it does 103km/h GPS verified.
Up to 75V it still does 95km/h
 
dominik h said:
QS60V5000W 10 years old, Battery is 21S5P (total 100Ah) Li-NMC Cenat Power pouch cell, rated continous discharge 8C charge 5C
Without weakening field and full battery (87V) it does 103km/h GPS verified.
Up to 75V it still does 95km/h
Click to expand...
Do you have any pictures or more info you can share on your battery? I am considering this similar setup

Sent from my Pixel 6 Pro using Tapatalk

 
To big to heavy and not enough capacity. :wink:
I had to lenghten the wheelbase 4cm to fit the battery. The battery wheight is more than 70kg.
If I had taken storage type cells, there would have been 150Ah in my scooter with less wheight. But who cares, they where for free and had to be "receycled". :lol:
 

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I've got a 6.7KWh battery (28s20p pack) that I'm planning on pairing with an 8KW hub in my CBR125 conversion. From the information I've gathered I'm expecting to get around 100km (60 miles) of range out of it at about 80kph.
It's not a long range commuter bike so I'm fine with that.
It may not answer your question fully, but it at least provides you with another approximate data point.
 
My 140lb sur-ron with 72v 32ah battery. Top speed is around 55mph (geared for hill climbs) and I am lucky to get 25 miles out of her. You might be able to get more range and bottom end balance if you had gearing and could shift into a higher gear (less work for the motor at a higher speed).

But unless you have a reason for wanting to be quiet (Riding where you shoudn't be :mrgreen: ) A gas bike is going to be cheaper and better in every way.

Sur-ron in action:
[youtube]ivG-yOOF-Og[/youtube]
 
Hi, I have a new QS273model 13inch 8000W Hub Motor V2 Type to replace an old one (5Kw) destroyed. I need to reconfigure the scooter SEVCON controller so that it works correctly.
Does anyone have the .DCF file to configure this motor with this controller?
The old motor was a V1 type, so it has different pairs of poles, so a direct replacement does not give good results, as can be seen in this video.
[youtube]SzLuL1R81Pw[/youtube]
 
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