Planning my first E-motorcycle conversion

[ajhyp]

Hi guys a total newb here.
Been trying to wrap my head around this and only figuring out I should’ve stayed in school
Here comes a bunch of questions and possibly more.

I have a Honda 125cc sitting back home.
Planning to electrify the thing when I get back.

Going to stay on the road.
Top speed: 130km/h
Distance at 60km/h: 80km+

Motor: QS 273 8kw hub
Controller: Kelly 96501-8080H: 200A C, 500A P
Battery: 72V? 96V?
Rim: 18” motorcycle
Apprx weight with rider: 210kg+-

Q1: Is a 273 motor suitable for this kind of build?
Q2: How much torque would it be running at 200A? Would 400A max be ’torquey’ enough?
Q3: Is there a similar power controller with a smaller profile?
Q4: What Battery spec should I aim for? (I’m heavy on the throttle)
Q5: Would I benefit from a 96V system instead of a 72V? In terms of acceleration/speed?

Any tips/suggestions or directions to helpful resources would be very much appreciated.
Thanks and keep on inspiring me!!

 

[amberwolf]

Hi guys a total newb here.
Been trying to wrap my head around this and only figuring out I should’ve stayed in school

First, I highly recommend reading as many of hte threads as you can for all the other scooter and motorcycle conversions (finished or not) here on this subforum. They will give you an idea of what problems you may run into, and what kind of power requirements there are for your specific situation and riding style/needs.

While it may seem like a lot of reading, it's going to show you a bunch of things you probably haven't even thought of yet.

You also need to check with your local legal codes, because in some places, you may not be able to get this road legal, or at least it may require a lot of hoops, paperwork, time, and money.


Some thoughts on battery size (not type or capability, just capacity and physical size/weight).

Top speed: 130km/h
Distance at 60km/h: 80km+

(pardon me for converting everything to mph; it lets me think in terms I know well)
80mph is probably going to take 100-200wh/mile, depending on aero of bike, wind and terrain (perfectly flat, or very slight slopes), riding style (quick starts or slow rollup to speed, lots of stop/start traffic, or just open-road riding, etc).
37mph is probably going to take 60-100wh/mile, depending on same.
If you have hills, then total weight also comes into play, and the exact slope of the hills, and can greatly increase your power usage (perhaps more than doubling for more than a few % slope).


So assuming worst case (always a good idea), then if you ride only at 37mph, 50 miles of range will take 50miles * 100wh/mile = 5000wh. This is probably going to be about 80-100lbs, and about the size of a human torso. It would probably fit within the space of the original motor, transmission, and gas tank, etc., though it may require frame modification to fit it depending on shape.

If you rode only at 80mph, then worst case 200wh/mile for 50 miles is 10000wh, so twice as big a pack, thus about twice the weight/size as above.

If you have some mix of the two, you'll need to figure out what percentage of each you have to figure the pack. For an easy example, if it's 50/50, then you need 5kwh for the 80mph section, and 2.5kwh for hte 37mph section, so 7.5kwh total, and roughly up to 150lbs of battery, bigger than a human torso.

WIthout knowing your exact situation and numbers it's hard to give more than guesstimates, which could be well over or under actual needs. For instance, "hard on the throttle" means using a lot more power for startups, especially if you're riding in traffic or city situations where you have to stop and start a lot.

If you like, there is a simulator at http://ebikes.ca/simulator that can help you figure out power needs, and what kind of acceleration rates you might get at various power levels and situations. It's meant for ebikes, but there are higher power motors on there, like the Cromotor, and you can enter custom numbers for everything if you have a basic idea of what a particular part would be, to get closer.

Q2: How much torque would it be running at 200A? Would 400A max be ’torquey’ enough?

To find the torque the specific motor will give you, you need to go to the QS site and find their dyno chart for that motor (if they have one), and the curve that is closest to the volts/amps you'd be using with it. It'll probably be in Nm. If it's for the bare motor, then you use the wheel size you'll use, along with the Nm of the chart, to calculate the actual torque at the tire/road at any particular speed.