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Author Topic: Electric Race Bike Project  (Read 520 times)

J.Timpson

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Electric Race Bike Project
« on: April 05, 2017, 07:06:03 PM »

Hi all,

Im currently designing an electric race motorcycle as my final year university project. This is 100% theory due to the cost.

I am having issues with finding the amount of batteries I need to use for my chosen motor and application. The motor in question is a Parker GVM 207Kw 103Kw/h motor. This needs to be able to reach 180mph and last 40miles at an average speed of 110 mph. This is being designed for the isle of man TT.

The motor efficiency is 95% the controller is estimated at 80% as i have not chosen a controller yet. I have calculated that it needs 104kw/h to the rear wheel to achieve these figures. But i am now lost as to how many batteries i need to fit in this motorcycle. As i will be doing a 3d model of this i need to know how many batteries and the weight of them. The total weight of the motorcycle must not exceed 300kg. Can anyone please help me as i am an electric vehicle noob.

Cheers
John
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Doug S

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Re: Electric Race Bike Project
« Reply #1 on: April 05, 2017, 08:15:46 PM »

First thought...I don't think you've posted the motor spec correctly. The 207kW rating makes sense; that's the equivalent of 277 horsepower, which seems in the ballpark (if a little aggressive) to reach the top speeds you've indicated. But what's with the 103kWh? kWh is a total energy number and doesn't make any sense for a motor...it's a number you use for a battery pack to indicate its capacity.

Speaking of battery capacity, you've run head-on into the problem high-performance EVs run into. 104kWh is a LOT, though maybe in the ballpark for the kind of performance you've indicated for 40 miles. But for reference, the biggest battery Zero puts in their machines (not including the auxiliary "power tank" battery) is 13.0kWh, and that weighs somewhere around 140 lbs (63kg). Scaling that up by a factor of 8 gets you where you need to be in terms of capacity, but puts you at 1120 lbs (508kg) for the battery alone...not gonna work. For another reference point, Tesla just came out a few months ago with the largest battery pack they've ever put in a car, at 100kWh. I don't know how heavy that is off the top of my head, but it's far too big to squeeze into a motorcycle chassis.

First, check your calculations carefully. Mugen has won the last three TT Zeros at better than the 110mph average you want, and though I don't know the capacity of their battery (not too much information is available as the design is proprietary), I do know they don't have 1120 pounds of batteries on their bike. Second, you should be able to exceed 90% efficiency on your motor controller, with 95% as a reasonable goal. Third....good luck. Racing vehicles are voracious in their consumption of energy, which is pretty much the biggest weakness EVs have with current technology.

Welcome to the wonderful world of Engineering.
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Fred

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Re: Electric Race Bike Project
« Reply #2 on: April 05, 2017, 09:08:13 PM »

Final year at university and your getting your units mixed up? You may need to study a bit harder. Also, if it's only theory why do you have a Ducati GP bike?
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Doug S

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Re: Electric Race Bike Project
« Reply #3 on: April 05, 2017, 10:05:12 PM »

I don't know if I'd say Fred's comment was actually abusive, but it was pretty harshly worded.

I'm a little concerned, myself, though. After I showed you that you have a battery capacity problem, you INCREASED your required capacity from 104 to 137kWh. You realize that just makes the problem worse, don't you? Okay, sure, that's just electrical stuff, but ANY engineer should be at least conversant with important Physics units and understand the importance of their magnitudes.

You're doing something basic very wrong.
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Shadow

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Re: Electric Race Bike Project
« Reply #4 on: April 06, 2017, 12:18:17 AM »

OP please clarify are you from an engineering background?
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Fred

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Re: Electric Race Bike Project
« Reply #5 on: April 06, 2017, 01:13:14 AM »

I don't know if I'd say Fred's comment was actually abusive, but it was pretty harshly worded.
Perhaps my comment was a little blunt but we're essentially saying the same thing, Doug.

Anyway, the final marks for his degree will pull no punches and at this rate looks like it'll be the harshest of all. Better to have some honesty now when it might help, than when it's too late.
« Last Edit: April 06, 2017, 02:31:31 PM by Fred »
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Shadow

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Re: Electric Race Bike Project
« Reply #6 on: April 08, 2017, 08:22:58 PM »

A request by OP that their account be deleted, has been processed.
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Fivespeed302

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Re: Electric Race Bike Project
« Reply #7 on: April 27, 2017, 02:44:16 AM »

Sounds like he needs to change majors.  And I don't care if that hurts someone's feelings.  Reality will sort it out eventually.
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