Extremely New Looking for Advice

[quaillover]

Hello, everyone.

I've been lurking a bit and trying to research how to make an emotorcycle. I'm getting to the point where I know I need to start asking questions, because I'm becoming unclear on how to actually design it, as I suffered a major concussion a little while ago and it's a bit difficult to learn some things. I'm confident I can learn and build it.

I've watched the Benjamin Nelson video series, read a bunch of the builds here and elsewhere.

So first things first! The case!

MOTORCYCLE
I actually don't have a particular donor bike or frame yet (I know, I know). I have the options to get an inop 1973 Yamaha tx750, an inop 1974 Honda CB550, a rolling frame 2007 Ducati Monster, or a 2014 Triumph Bonnevile/Thruxton frames. These are all in the same price range.

LOCATION
I live in a mountainous area., I live between two cities and both are about 20ishmiles away using a particularly notorious mountain freeway. Now what I would use the motorcycle for, would be to get to work.

To get to where I work there is a nonfreeway mountain backroads option, that has a speed limit of 45mph, It's about 25 miles one way. I have attached the elevation profile from Grin's trip simulator to give an idea of the elevation. I can charge it where I work, and I 10 hour+ shifts. So plenty of time for charging.

CURRENT DESIGN THOUGHTS
I would like to have about 50 mile range and a top speed of about 55mph. (Give some wiggle room on the mountain.) I believe that a mid mount motor would be best because of the extra torque, correct? I am also not sure if regenerative breaking would be useful or not.

Essentially I'm looking at this kit as a starting point: EMX® QS138 70H V1 Kit

The quick facts of the kit:
Motor: QS138 70H
Controller: EM-260SP
Batteries: 72v, and 48AH - I think I would need more AH correct?

I can't figure out how to find the data needed for the motors into Grin's motor simulator. I've found some of the date. If I could figure out where to get (or calculate) the values for that, that would help. I've looked up multiple website trying to find manuals, but to no avail.

Thanks in advance. If I am completely off base, let me know.

 

[jpgey]

Hello, I would choose a frame that's easy to work on, as the 2014 Triumph Bonnevile/Thruxton but the bike will be heavy and that's not something we want. 50 mile range and a top speed of about 55mph are somewhere ambitious regarding the elevation, at a glance a battery around 7 kWh not 3.
Nice project !

 

[quaillover]

Thanks! I love the look of the Thruxton, would love to use it, but not sure.

So I have the initial calculations...did I do this correctly?

All the values for weight and dimensions are from the stock 2014 Triumph Truxton.

 

[quaillover]

I ended up finding a good priced 1979 Yamaha RD250 frame, and picked it up!

 

[Chalo]

I ended up finding a good priced 1979 Yamaha RD250 frame,

Dang, that's a good donor. Double cradle, not too horribly heavy, with very reputable handling for its day.

I would try to round up aluminum motocross rims for your wheels, and preferably less hefty hubs too, because suck loses to anti-suck every time. But if the budget is super tight, then using the original stuff will work just as well as it did originally.

 

[quaillover]

Thanks for the advice! I found some mistakes in cells for the excell sheet, but I've fixed them.

Does this sound right: For going 5 miles at a 10 degree incline, maintaining 50mph
Motor: Peak 20.1kW, rated 6.7 kW and a minimum of 2.1kwH for a battery.

Most of the rest of the trip (20 milesish) is fairly flat - so maintaining 50mph:
Peak: 10.7kW, rated 3.6kW and about 4.3kwH for the battery.

With these stats:
I should look for a brushless midmount motor with a peak of 20kW and a rated of around 6kW. The battery should be about 8kWh?

 

[jpgey]

In my experience, these figures seem consistent. Nevertheless, you'll need to find room for the battery, so perhaps use a hub motor ?

 

[quaillover]

It's definitely, something I'm considering. I just need to figure out volts, amps, and amp hours next.

 

[Dui ni shuo de dui]

Hi,
Given the data and the description of your needs I'd rather go with a hub motor.
Main reason being you'll need as much space as you can get for the battery.

The range is always very difficult to estimate because it can vary so much from one person to the other, depending on riding styles. My rule of thumb is 1Ah = 1km of range, riding relatively quick and not being soft on the throttle. So in your case with 50 miles that would be 80km so around 80Ah of capacity.
But again, this is very dependant on how you ride so that's just a rough estimate.

So that's like at least 6KWh of battery to store in the frame. I'm less enthusiastic than Chalo about the frame you got since its available internal volume shape won't make it easy to fit any brick shaped battery, and you won't be able to make the battery very high either since there is a metal bar going right in the middle. So that means pouch cells are probably out of the possible range of choices, which isn't great as usually pouch cells are a bit more performant than cylindric ones.
I guess the only option left is cylindric cells, so that means a complicated pack with a weird shape out of many, many 18650 cells. Don't get me wrong, that will work and that isn't necessarily bad, but it's a lot more hassle to build.

For the motor, I believe a 8KW QS 273 3T hub motor should do the trick. You can go for even higher power as it should heat less, but then they tend to get heavier. Get one with the cast aluminum rim, the spoked ones heat much faster. It's difficult for me to evaluate how hills can affect the motor as I live in a mostly flat area, but a bit of statorade really helps so there's always some wiggle room there.

Just my two cents, wish you good luck in your project!

 

[quaillover]

Hmm, I'll keep that in mind. I'll be getting the frame this week, so I'll be able to start measuring out everything.

 

[SlowCo]

I also vote for a hub motor so you have more space in the frame for a battery pack. Nice project and good luck building it!

 

[quaillover]

Just got the frame. It's actually a 1974 Yamaha RD350. (At least that's what's written on it )

 

[E-HP]

That was a fun bike to ride. Hit that two stroke torque peak and you get that front tire pointing at the sky and big grin on your face lol.

 

[quaillover]

Well, got a QS 273 8kw motor kit ordered. Just waiting on shipping at this point. Picked up a swingarm for a song, on eBay, and am looking at the rest of the parts for the rear.