Cruiser Motorcycle conversation components

S

shaman

1 kW
Joined
Dec 10, 2018
Messages
343
Location
Fort Worth, TX, USA
In addition to developing VESC based open source controllers, I would also like to convert a cruiser style motorycle to electric for funsies. I have absolutely no experience with this and my mechanical design skills are not even close to my electrical...which aren't the best either. I have spent time assessing potential batteries, BMS, motors, and motor controllers. I will list what I have found but this thread is to open up the possibilities with advice from more experienced or smarter people than I. I don't want a hyper driven torque rocket to help shorten my life span, just a cruiser with above average acceleration that will reach about 90mph max. Budget is max of $3.5k USD for everything. Here's what I've found so far for components.

Donor Bike
Any scrapped harley Sportster or Honda/Yamaha cruiser style bike

Battery
16s 45ah modules. At least 2 in parallel. 7C continuous and 10C pulse
https://www.techdirectclub.com/lg-c...olar-rv-golf-car-battery-60-vdc-each-2-5-kwh/

BMS
300A smart BMS from Ali. Has been tested and reviewed extensively by others on the sphere.

Motor
ME1304 or similar or bigger if need be. I need help with this one as someone has already advised that the shaft may not hold up to the torque needed for this application

Controller
Mobipus. Easier to acquire and program for the DIYer than something like a sevcon. Kelly seems to have a bad reputation but if someone has a success story for something like my application then I'll hear it.

I welcome anyone with good knowledge, experience, or insight to provide advice on these component choices. Thanks!
 
SlowCo said:
Too bad tey ar so expensive but I always thought that for a cruiser/chopper build a powerful watercooled hubmotor would be ideal:
http://www.cnqsmotor.com/en/article...DC Electric Hub Motor For motorcycle/538.html

http://www.cnqsmotor.com/en/article... kits for Electric Racing Motorcycle/607.html

That way all of the space that the ICE took can be used for the battery pack. And no need for fabricating a motor mount or gearing.

20180127095612_433.jpg
Click to expand...

Yeah I had the same thoughts but those hub motors destroy my budget. Maybe one day :)
 
Hub motors lock you into the one gear ratio too. I want to be able to change gearing with different sprockets. Just in case my calculations are wrong, or I decide I want a little more top speed at the expense of acceleration at some point down the line.
 
So after doing more planning and research, I see that the brushless motors like the ME1304 or ME1507 do better with higher voltage. I'm now looking to do a 32s battery by connecting the 16s modules in series. This puts my max voltage at 128V since I will be charging to 4v per cell for longevity purposes. The problem is finding a reasonable controller than can handle voltages that high with the 15kW continuous power I want. Certain Curtis controllers can handle that but they're really expensive. Sevcon seems like a pain in the d*ck to set up for programming. Kelly's 8080IPS controllers looks ok but I hear mixed feedback about those. The Mobipus 96400 can do the trick but I'm not having luck getting quotes on the Mobipus stuff. Often I find that the "96V" controllers can handle at least 128V max. Does anyone have any suggestions?
 
I've been thinking along the same lines you have. If you're committed to using the LG Chem modules then the Sevcon is out. 1 module is too low voltage, and 2s is too high.

I sent a message to SamD to ask if the Mobipus 600a will work with a single 60v module. I'd like to use 3 of the LG chem blocks in parallel, assuming the controller will continue to work down to their full discharge voltage ~49v. That seems like the best option to me as long as the Mobipus doesn't shut itself off automatically at 60v or something.

For the motor I'm thinking ME1507, or ME1616 if water cooling ends up being necessary. This design works fantastic in the Zero bikes at about the power level I'm after.
 
Mandres said:
I've been thinking along the same lines you have. If you're committed to using the LG Chem modules then the Sevcon is out. 1 module is too low voltage, and 2s is too high.

I sent a message to SamD to ask if the Mobipus 600a will work with a single 60v module. I'd like to use 3 of the LG chem blocks in parallel, assuming the controller will continue to work down to their full discharge voltage ~49v. That seems like the best option to me as long as the Mobipus doesn't shut itself off automatically at 60v or something.

For the motor I'm thinking ME1507, or ME1616 if water cooling ends up being necessary. This design works fantastic in the Zero bikes at about the power level I'm after.
Click to expand...

Originally I was gunna go for running 2 blocks in parallel and have an approx. 60v battery like you. The problem with that for me was the max RPM that those ME motors would be running. I would need about a 1.4 gear ratio to achieve my desired highway speeds which is too low of a ratio for my tastes. Running them at 128v would give me an RPM of roughly 4400 which would allow for a gear ratio of about 3 for the motorcycle and less current flow to achieve the same power output. I am more comfortable with this ratio and seek to find a suitable controller.
 
shaman said:
I don't want a hyper driven torque rocket to help shorten my life span, just a cruiser with above average acceleration that will reach about 90mph max. Budget is max of $3.5k USD for everything.

Battery
16s 45ah modules. At least 2 in parallel. [...]
BMS
300A smart BMS from Ali.
Click to expand...

59.2V nominal, times 300A, equals about 17.8kW electrical. You'll be doing quite well to net 14kW mechanical power from that, and you'll need to be a little bit clever to make that amount of maximum power correlate with the top speed that uses that much power.

Depending on the motorcycle and riding position, 14kW will get you about 65mph. Maybe 70.

Frankly, I think even a 65mph e-motorcycle is a very ambitious goal for a $3500 budget. I hope you manage to do it.
 
Chalo said:
shaman said:
I don't want a hyper driven torque rocket to help shorten my life span, just a cruiser with above average acceleration that will reach about 90mph max. Budget is max of $3.5k USD for everything.

Battery
16s 45ah modules. At least 2 in parallel. [...]
BMS
300A smart BMS from Ali.
Click to expand...

59.2V nominal, times 300A, equals about 17.8kW electrical. You'll be doing quite well to net 14kW mechanical power from that, and you'll need to be a little bit clever to make that amount of maximum power correlate with the top speed that uses that much power.

Depending on the motorcycle and riding position, 14kW will get you about 65mph. Maybe 70.

Frankly, I think even a 65mph e-motorcycle is a very ambitious goal for a $3500 budget. I hope you manage to do it.
Click to expand...

I agree that the raw power is there by calculation but the RPMs are less than ideal at 59.2V nominal. The required gear ratio just seems really low in that situation. Maybe field weakening could close the gap? I could just be worrying for no reason. I don't actually have any experience in this to back my concerns. Also, 65 - 70mph would be good enough at this point.
 
shaman said:
The problem with that for me was the max RPM that those ME motors would be running. I would need about a 1.4 gear ratio to achieve my desired highway speeds which is too low of a ratio for my tastes. Running them at 128v would give me an RPM of roughly 4400 which would allow for a gear ratio of about 3 for the motorcycle and less current flow to achieve the same power output. I am more comfortable with this ratio and seek to find a suitable controller.
Click to expand...

Good point. I hadn't thought about the relationship between rpm and system voltage. Can you explain how that's calculated?
-edit and you're right, the field-weakening function in the controller probably comes into play here. I wish the documentation on the Mobipus 72600 was a little more thorough. I might have to pick SamD's brain to figure out how that works.
 
Mandres said:
shaman said:
The problem with that for me was the max RPM that those ME motors would be running. I would need about a 1.4 gear ratio to achieve my desired highway speeds which is too low of a ratio for my tastes. Running them at 128v would give me an RPM of roughly 4400 which would allow for a gear ratio of about 3 for the motorcycle and less current flow to achieve the same power output. I am more comfortable with this ratio and seek to find a suitable controller.
Click to expand...

Good point. I hadn't thought about the relationship between rpm and system voltage. Can you explain how that's calculated?
-edit and you're right, the field-weakening function in the controller probably comes into play here. I wish the documentation on the Mobipus 72600 was a little more thorough. I might have to pick SamD's brain to figure out how that works.
Click to expand...

https://sep.yimg.com/ty/cdn/yhst-129399866319704/ME1507MotorData.pdf

Motors will have an RPM/V, V/RPM, or kV rating that all describe the same thing. The ME1507 has 0.026 V/RPM as per the data from the link. The inverse of this is RPM/V which is 38.46. Multiply that number by your system voltage and that will be the unloaded RPM(I think) of the motor at that voltage. The ME1616 has the same spec as its just a liquid cooled version of the ME1507. Field weakening is a technique that essentially alters the RPM/V rating on the fly at the sacrifice of torque.
 
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