140km/h 11kw motorcycle battery calculations, HELP!!!

[khazimodo]

Hi guys
This is my first post on endless sphere. For a while I have been planning an electric motorcycle build, inspired by the 11kw Zero motorcycle model. Now while I love the tech of zero motorcycles, I am not a fan of Zero's aesthetics or price. The motorcycle I plan to build intends to be lighter, while not as powerful as the Zero 11kw. I am still new to electrical engineering and would appreciate any help!
The motor I have selected is the Revolt RV-160Es http://www.revolt.org.il/rv-160-model/rv-160es/
I am planning to use the 70kv version running it at 84V, to achieve a top speed of 140km/h or 87mph.
The calculation for this is shown below, would appreciate anyone's input on this.

The motorcycle rear wheel rim is 17inches. Using an online wheel rpm calculator, the tyre rpm = 1392.56 rpm.
The motor rpm = tyre rpm x gear ratio
The gear ratio I want to use 4:1
Motor rpm = 1392.56(4) = 5570.24 rpm
That would be the motor rpm under load. Therefore for the motor rpm with no load = 5570.24/0.9 = 6189.18 rpm @ no load
Using this I can calculate the motor kv = no load rpm/volts
6189.18/84 = 73.68 kv

Now here is I am really stuck, the batteries and the ESC!!!
According to the Revolt website

100-150Kg total weight (vehicle+ driver) a 45- 60A cont. current (battery amps) controller should be enough

The total weight of my motorcycle aims to be 90-100kg excluding rider.

With this being said I found a 12v30Ah pack https://www.globalsources.com/gsol/I/Lithium-ion-battery/p/sm/1170409262.htm#1170409262

Using 28 of these 12V30Ah packs, I plan to use a 7S2P layout to get 84V with 60Ah. According to my basic understanding the battery should produce a continuous current of 60 amps for 1 hour before being drained completely. I only plan to use the vehicle for no more than 45 minutes a day. Will 60 amps be enough or should I go for 90 amps? Bearing in mind weight is critcial!

Have I got this correct? Any improvements or recommended 12V battery packs would be greatly appreciated

Also Revolt mentions that there motors will work Sevcon and Kelly controllers that accept 120 degree hall sensor angle, do you guys recommend any controllers?

Looking forward to all your opinons, thoughts and advice!

Best

Khazimodo

 

[ecustom]

While I certainly am no expert (no experience - yet) I will throw some discussion points in there regarding your pack. That 12V LiFePO4 pack is really a 4s1p pack with cells having 3.3V nominal (and a 30Ah capacity). So what you are considering is a 28s2p pack giving you 92.4V nominal (using 14 such packs. You mentioned 28?). You will need a 28s BMS to monitor your pack.

92.4V * 60Ah is 5.5kWh. Some say, from experience, that 5kW is roughly enough to sustain 100km/h (depending on wind resistance constant it might go up to 10kW. Wind resistance plays a huge factor). That mean upper limit of your battery capacity at 100% efficiency is 100km at 100km/h.

 

[flat tire]

The motor looks quite good for the price and I have saved the manufacturer. The battery might be better off with lithium ion instead of lithium iron for twice the energy density.

How much power to sustain 140 kph depends drastically on aerodynamics. So even a fairing can reduce your constant power needs by several kW.

Sevcon is good if you can find a professional to pay to configure it. ASI BAC4000 or BAC8000 are also good, easily configurable options if you are willing to buy their "evaluation package" directly from the manufacturer. Not ERT, cuz a bunch of people recently popped up on here again to complain about him not sending stuff.

 

[DanGT86]

I would like to add that in all my years of being on this forum I have never heard of a single person being happy with a revolt motor. I have no experience with them personally. Like many people on this forum I was very optimistic about them at first. They seemed like they would bridge the gap between small RC motors and the large heavy motors like zero and motenergy. I've since seen countless complaints about their quality control, poor efficiency, and heat issues at power levels way under their spec sheet ratings.

Id suggest you take a look at the 3000watt qs mid drive motor. There is also a 1000 and 2000 watt motor in their lineup that might suit your needs. They are relatively cheap matched with 14kw controllers.

https://endless-sphere.com/forums/viewtopic.php?f=30&t=93627

Best of luck to you on your build.

 

[khazimodo]

Hi Guys
Many thanks for all of your input.
The motorcycle will be faired.
I am definitely going to look further into battery packs available, now that I have abetter idea on what to expect, thanks ecustom!
Thanks flat tire for the controller recommendations too!
And thank you DanGT86, for your info on revolt motors. I have been looking at the QS 17inch 10kw hubmotor and I am quite impressed with it's stats!
Will let you guys know what I come back with

 

[larsb]

I own two revolt motors and the qs3000w mid drive, both revolts are low quality, seller is not to be trusted.

I am really happy with the QS 3000W motor, it’s a bargain. I don’t think it can do 140km/h continuously though, QS specs it at 100km/h and it takes more than double the power used at 100km/h to go 140km/h.

My moped used to go 110km/h with APT96600 controller and the QS 3000w motor, 72V30Ah battery, 17" wheels, 4.77 gearing.
I think with a lower gearing it could do 140km/h in burst. It takes a lot of kW to go that fast.

The zero with top speed of 139km/h is speced at 33kW peak, just as a reference to what you are comparing to.

Let’s say you need 20kW@72V at the rear wheel to do 140km/h, that’s between 280-330A battery current with 85% system efficiency (depends on where you have the losses).
So no, you won’t do it even with a 90Ah lifepo4 battery as it typically can output 1-2c discharge rate or 90-180A for a 90Ah battery.
18650 cells or lipo is a better choice if you want to keep to a smaller battery capable of roughly 300A. 20S30P battery of a good cell would be large enough for that kind of current