SiAECOSYS Power Chart

I could barely pass the Captcha test to join this group so bare with me.

Building my electric motorcycle and trying to do the battery math to determine what AH to get. I look at the QS motor chart to try and figure the hub motor RPM vs Amps draw. The far left column is Volts I am guessing from the pink "V". It starts out at 0 volts where nothing is happening all the way to 180 volts at 25kw and 2000 rpm. I thought volts were the constant, but maybe not. So when trying to determine the amp draw at 50mph or 800 RPM it says 120amps, but it lines up with 72 volts. For an RPM of 1600 I get 144 volts. How do I know the amps I will draw based on wheel speed if my bike is always 96v?

My math says my 20kw QS268 and ND961800 will go 18 miles at 60mph on a 100AH battery. Does that sound correct? I see guys with this kind of power on Surrons go much farter. I was in the Marines so I have crayons and graph paper.

Thanks for any help.

Which chart are you refering to?

Forget the chart...
For a constant 60mph you need between 6-8kw from the battery
On 96V it then draws 60-80A. from the battery. You can drive 60 miles or more with your 9kwh battery at 60mph constant.
During acceleration the controller can feed the motor with much more power. Your 961800 can draw up to 800A / 70kw from the battery , if the motor can take this and the battery can handle that much current.

thanks. here is that chart.

my goal is only to drive about 20 miles at 50 - 60mph. and of course way less if I want to make fast runs near the house. I tried a bunch of calculators online, but the all seem to have some variable that I have no idea what it is. Like "Maximum Load Capacity in Kg". I want the smallest 96v battery I can get and have no idea how small that is. So at 60mph, 20 miles would be 1/3 of an hour. Does that mean I only need a 26AH battery?

If you can build or get a high C-rated battery (20C or more) than 30-40Ah would be enough, but smaller batteries have higher voltage drop under load and you will loose power much earlier.
With that Controller and 20kw QS268 I would go for minimum 50-60Ah to get lower sag.

If you want to use 50kw peak power from your system, it would draw 550A from your battery. With only 26Ah you have to find or build a 20C capable battery and will probably have temperature problems inside your battery.

I have an 21S100Ah made of 8C continous rated cells.
I have restricted my controller to 400A and have @400A 5V voltage drop at 25 degrees Celcius, with 10 degrees Celcius the voltage drop raises to 10V. Then the controller starts to reduce power at around 50% SOC.
This battery gives me on normal rides in summer around 100km or 60miles. My battery is 6 years old and still going streng.

If you want to build a 1/4 mile drag racer, then go for 50-100C rated RC-Lipo Packs and be aware that they will only last 50-100 cycles.

That's really helpful info. Thanks. Now to learn about C rating. LOL

If you have a 100Ah battery rated for 3C you can draw 300A from it, if it is rated 8C you can get 800A from it.
There exist als C-ratings for 10seconds, but I would not go for them.

If the single cells are rated 8C continous the battery pack will still struggle to give you 800A for longer periods because the cells in the middle of the batterie can not get rid of the heat they will produce. But you can get 800A from them for acceleration periode 5-10 seconds and 150-200A continous without overheating them.
My 70kg 21S100Ah 8C continous battery pack had a water cooling in his previous live. Then it was disassembled and reconfigured without water cooling, because I had not enough space for it in my scooter.


Normaly people start with smaller projects. A 70kw controller and a 20kw motor is not the cheapest thing to learn the basics, but if you get it running, there will no need to go bigger anymore

Thanks. I keep watching everyone go up and bigger so I figured I may as well start bigger. And I would like to bigger than I actually need so I do not have to stress stuff.

Question? Is there anyone like a regular joe here I should be getting to build my battery instead of going to ALiExpress or other places?

tedo said:

my goal is only to drive about 20 miles at 50 - 60mph.

Click to expand...

If you’re planning to ride 60mph among cars, then consider targeting 70 mph+ for your top speed, for safety. You probably know that to stay alive on a motorcycle, you have 3 routes to escape a dangerous situation, maneuvering, braking, and acceleration (a good horn sometimes helps). If you target 60mph, you eliminate one of those escape options.

For budget, hit up Amorge, give them your battery space dimensions, max, and fill it up with 96v. there is a guy in facebook groups electricmotorcyclebuilds, Anthony Stone, very knowledgeable on lithium polymer cells, safe and high C rate. Could be a great choice for your build.

I ended doing the Amorge Battery. 96v 60ah

I do about 60mph with a 72V 25ah junkyard ev cell pack. About a 4500w continuous loading of the motor.

It gets me about 18 miles. I weigh ( me and b9ike) 280-420lbs typically on my daily rides.

You will be more than fine with a 96V Amorge.

Amorge is ( not budget builder) one of the best if you are buying packs. Nothing but positivity, packs take a few years to die, many happy buyers.

I am currently looking at the ND 144V 300A.

How do I know the amps I will draw based on wheel speed if my bike is always 96v?

You must use linear extrapolation ...

Or become familiar with this simulator and its merits. Very many variables to consider. Friend. this can help.