# Speed Junky Building a EV - motorcycle



## sumfoo1 (Mar 16, 2010)

I need some choice with engines... 

My front runners are the PMAC DC-28
http://electricmotorsport.com/ev-pa...ss-57hp-liquid-cooled-pmac-motor-24-120v.html

38kw just doesn't seem like enough coming from the 120hp sport bike world 

The HPEVS (with the 144v controller atleast) with 100ah cells
AC-20 73hp 
AC-35 85hp but more weight 

Can these motors be pushed any harder? 

The Evo Ax-130 seems ideal but i can't get a price or a quote from anyone it seems like its probably worth more than a new motorcycle or its rare or something. Assuming i can find one this pushes me up into the 600v range but what size cells do i need? I feel like i only need 10-15 kWh in cells for my range at cruising speed but i don't know if 188 50AH cells will support the max amp draw from the motor (and damn that seems like a lot)
http://www.evo-electric.com/inc/files/AF-130 Spec Sheet V1.1.pdf

The range i want is really only 60-70 miles with 3 or 4 full throttle punches for 5 seconds or so on the way. 

Can i run any more voltage to the HPEVS motors? With what controller? 
the 73/85 hp is probably plenty... but i'm the kind of guy that tends to go overboard on power (I have a twin turbo 500cid '61 ford galaxie that makes 1600hp (estimated pegs a 1500hp dyno 1500rpm before redline) at 18psi)

I'm a mechanical engineer by trade so i'm pretty good with powertrain and i understand my way around electricity but i just don't know how hard i can push things. 

Any help would be nice... i'll probably just go with 144volts on the ac-20 with 100ah batteries but any assistance finding more power would be awesome.


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## frodus (Apr 12, 2008)

One thing I'd recommend..... is Start thinking a tad differently 

Think TORQUE and not HP. While HP does come into play, Torque has a more direct influence on acceleration. If you have a decent motor with good torque, you'll never need 100+ HP for road-speed. Think about max torque being 100ftlbs or so, and lets say there's a 5:1 ratio.... that's 500ftlbs at the rear axle. Nothing to sneeze at.

Not exactly sure where 188 50Ah cells came from, that's 30kwh. Ah x Volts = Wh. If you used 100Ah CALB cells, and went with 32 of them and used the AC23 and 1238-7601 650A controller, you'd be in good shape. I doubt you could fit more 100Ah cells in a bike easily. If going 144V, the 1238-8501 controller is only 500A, so more or less the same power, but the 650A controller should give more current, and depending on which motor, more torque.
Look at this:
http://hpevs.com/Site/power_graphs/imperial/peak/pdf/ac-23/96-volt/650-amp/ac-23-96%20volt-%20650%20amp%20imperial%20peak.pdf
compared with:
http://hpevs.com/Site/power_graphs/...-amp/ac-23-144 volt-500 amp imperial peak.pdf

Going 650A is going to give you a lot more torque!

I think you'd want more like 8-10kwh or so for only 60-70 mile range. If you're only doing 3 or 4 punches, I think 40-50kw is just fine. 

P.S. I PM'd you on electricmotorcycleforum.com, if ya feel like replying and emailing me. I can help source either the HPEVS motors, or the PMAC motor you linked.


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## sumfoo1 (Mar 16, 2010)

frodus said:


> One thing I'd recommend..... is Start thinking a tad differently
> 
> Think TORQUE and not HP. While HP does come into play, Torque has a more direct influence on acceleration. If you have a decent motor with good torque, you'll never need 100+ HP for road-speed. Think about max torque being 100ftlbs or so, and lets say there's a 5:1 ratio.... that's 500ftlbs at the rear axle. Nothing to sneeze at.
> 
> ...


Email sent yeah I don't know where I messed up on my 600volt mah before I guess my brain was fried after work. 

I agree with everything you said other than the hp/torque thing I just have a hard time reigning in my inner hp junkie lol


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## dougingraham (Jul 26, 2011)

sumfoo1 said:


> I need some choice with engines...


You mean motors. Engines are something else.



sumfoo1 said:


> 38kw just doesn't seem like enough coming from the 120hp sport bike world


It might not be enough for racing but for around town driving or cruising on a highway it will be plenty.




sumfoo1 said:


> The HPEVS (with the 144v controller atleast) with 100ah cells
> AC-20 73hp
> AC-35 85hp but more weight
> 
> Can these motors be pushed any harder?


Some but the problem is the controller, not the motor. Torque is limited by the current and total power by both the voltage and current limits in the controller. And if you are making the comparisons from the dyno plots on the HPEVS site they are apples vs oranges comparisons since the battery voltage is different in the different tests. They would be a lot closer in the HP comparisons if the voltage was the same with the same controller. The only differences being that of efficiency. Compare the 108 volt dyno plot at 650 amps with the 144 volt plot at 500 amps. With the 108 volt the torque drops below that of the 144 volt motor at about 6800 RPM. Below that RPM is it quite a lot higher. If you mean to go with a single stage reduction (no transmission) and pick a max speed this might be a better choice. With an approximately 24 inch diameter tire and a 6:1 reduction you would see a speed of about 80mph at 6000 rpm and torque would be about 390 ft-lbs (or lbs as it is the same with a 24" diameter tire). You might even want to do a 7:1 which would give an 8000 rpm speed of 79 mph but more torque (455 ft-lb at 6000 rpm) at regular speeds. Somewhere between 6 and 7 to 1 anyway.




sumfoo1 said:


> Can i run any more voltage to the HPEVS motors? With what controller?


The controllers need to be characterized for the motors. There really are very few choices. The AC-20 at 144 volts has a torque band that extends up to near redline (7800 rpm with redline at 8000) so extra voltage is not going to do much good. It might be better to use the 1238 controller and do 650 amps. The lower voltage will narrow the torque band some but increase the torque. Something to look at anyway.



sumfoo1 said:


> Any help would be nice... i'll probably just go with 144volts on the ac-20 with 100ah batteries but any assistance finding more power would be awesome.


For your first build the components you have selected should give you a pretty good experience.


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## frodus (Apr 12, 2008)

From my experience, most single-ratio motorcycles with motors over 30kW are in the 4:1 to 6:1 ratio. Some even go lower than that. I've seen ~3.5:1 used a few times. Anything over 5.5:1 would give you great torque, but starts limiting the top speed. Also, above 6:1, the rear sprocket becomes less of a dinner plate, and more like a pizza pan. In some cases, the sprocket would hit the swingarm.

You should be fine with a ratio under 5:1

Also, don't go below 12tooth on the front sprocket with these motors. Chains do not really like high speed tight radius bends. I've heard of a few issues with 10tooth sprockets and minor binding/wear issues.


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## sumfoo1 (Mar 16, 2010)

Yeah sorry I'm used to ice obviously.

My "ideal" top speed is 100 mostly because i spend about 9 miles on a road with a 70mph speed limit, the average speed of traffic is 80 mph... I want a little bit of oh shit throttle left after the 80 cruise speed. 

I think the 20 series motor could do it. Also the Siemens motors look like fun but they are heavy.


Yeah I knew that about the chain sprockets too... I have an f4i stunt bike too lol...


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## Karter2 (Nov 17, 2011)

Make sure you understand the relationship between speed, range, and battery size ( capacity, weight etc) .
Do you have a budget ? cost can dramatically alter the size and weight of your battery.


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## sumfoo1 (Mar 16, 2010)

Karter2 said:


> Make sure you understand the relationship between speed, range, and battery size ( capacity, weight etc) .
> Do you have a budget ? cost can dramatically alter the size and weight of your battery.


I do have a budget I mean everyone should right? but from what I've found 48 80ah lifepos with motor, controller, bms dc to dc inverter, and a battery charger gives me a few grand left to pick up a local bike with a blown motor contractors wireing etc.

Right now the is an f4i and a zx6 in the $2000 range. And I'm pretty good at welding aluminum so that's not a hurdle for me. Just worrying about battery space on those bikes.

Also to the point on the motors posted above, the 96 volt peaks power at 3200 rpm the 144 volt peaks power at 5000rpm... so you give the 5000 rpm motor a 1.56 gear ratio to allow it to peak at 3200 rpm... and you now have 136 ft-lbs vs 127ft-lbs


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## Yabert (Feb 7, 2010)

Maybe it should be a good idea to go try a Brammo Empulse or a Zero SR to give you an idea of what is performance with low HP number but high torque.

Instant torque is changing everything!


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## sumfoo1 (Mar 16, 2010)

Yabert said:


> Maybe it should be a good idea to go try a Brammo Empulse or a Zero SR to give you an idea of what is performance with low HP number but high torque.
> 
> Instant torque is changing everything!


I have ridden the zero s but have not been on a zero sr.

There is not a Brannon dealer local.


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## frodus (Apr 12, 2008)

1.56 ratio is way too low for a motorcycle IMHO. Even the original ratio is higher than that. 136ftlbs at the rear axle is terrible. You want to get something north of 400ftlbs.

Where do you live Sumfoo1?


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## sumfoo1 (Mar 16, 2010)

frodus said:


> 1.56 ratio is way too low for a motorcycle IMHO. Even the original ratio is higher than that. 136ftlbs at the rear axle is terrible. You want to get something north of 400ftlbs.
> 
> Where do you live Sumfoo1?



I just meant before the chain to compare the motors. 

4.25/1 is the lowest (numerically highest when speaking in typical final drive talk) i'd go for a final drive. 

I live in Raleigh NC. 
Team Power Sports here is a Zero Dealer.


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## frodus (Apr 12, 2008)

Nice. I used to live in Roanoke, VA and went to Raleigh all the time in college.

No Brammo near you, but let me see about my buddy who lives in Blacksburg. He has an Empulse R, same as mine. I'd suggest riding both if you're serious.

Building versus buying.... that's the challenge. I think we're at the tipping point right now with EV's. It can take a lot of time and money and trial and error to get a bike that performs even close to what you can buy. Lots of R&D went into choosing the right ratios, the right motor to get the top speeds you want, the right batteries/bms/controller/charger and integrating it all.

I build my own a few years back. 1986 Honda VFR700F, lead acid batteries, golf cart motor..... then I upgraded to lithium batteries, AC20 motor, full BMS.... and got stuck on the fabrication part. Even then, with nearly $10k into the bike, it would have gotten 50mi and maybe 90mph. Now I can hit 105mph and get upwards of 100mi range.

Just some food for thought.


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## Karter2 (Nov 17, 2011)

sumfoo1 said:


> from what I've found 48 80ah lifepos with motor, controller, bms dc to dc inverter, and a battery charger gives me a few grand left to pick up a local bike with a blown motor contractors wireing etc.
> 
> Right now the is an f4i and a zx6 in the $2000 range. And I'm pretty good at welding aluminum so that's not a hurdle for me. Just worrying about battery space on those bikes..........


 Precisely my point.
There are many options for battery packs, and basicly, the more you spend on cells, the lighter , more powerful, and physically smaller, they become.
I suspect you have something like Calb Lifepo in mind ?..
You may want to imagine how a 300lb battery might feel on a bike !
check some of the other Emoto builds and see what choice they made.


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## sumfoo1 (Mar 16, 2010)

Karter2 said:


> Precisely my point.
> There are many options for battery packs, and basicly, the more you spend on cells, the lighter , more powerful, and physically smaller, they become.
> I suspect you have something like Calb Lifepo in mind ?..
> You may want to imagine how a 300lb battery might feel on a bike !
> check some of the other Emoto builds and see what choice they made.



Good point... a couple banks of 30ah pouches get me down to a 200lb battery.


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