# Best power/size ratio for electric street bike



## appleseed (Sep 12, 2010)

i have been readin alot about ac vs dc but mostly everyone is comparing cost to Kw for ac vs dc

i am tryin to fiqure out whether a dc brushed, ac induction or a dc brushless would give me the best power/size ratio and generally the lighter the motor the better

i plan on converting an kawaski ninja 250 2007 the bike has a 25hp gas engine but i would liike to have a more powerful electric motor then 25hp replacing it

i looked at the ac 50 motor being good 

cost is not the issue its the size and weight for a given horsepower output

so wat u all think? dc? bldc? ac? thks everyone


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## frodus (Apr 12, 2008)

most of the time, lbs motor = lbs torque, HP has several factors (copper, what the motor RPM is wound for, brush size, cooling).....

For instant power, Series wound usually wins. Best power to weight is BLDC.



Don't look only at HP, look at size, you'll NEVER fit that AC50 in that bike, its an 8" motor, 12"+ long. Even if you could, you won't be able to fit high enough energy/power batteries in there to really have fun. The batteries will likely be the weakspot.

I'd suggest an AC15 or AC18 motor, and lifepo4 batteries.


Maybe start with a brushed motor like an Agni 95, its got a peak HP over 25hp, its light, high power to weight, easy to find a controller for, small.


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## appleseed (Sep 12, 2010)

lol oops i meant the ac 20

i like the agni motor but i feel tht a peak power of 25hp isnt quite high enough

would there be a way to have 2 agni 95r on the bike some how combining the power of both motors? i no ppl have done tht for cars ex white zombie but im not sure how they would

any links would be greatly apprieciated


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## EV-propulsion.com (Jun 1, 2009)

Hi, I sent you a private message that might help you.
Mike
www.EV-propulsion.com


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## frodus (Apr 12, 2008)

appleseed said:


> lol oops i meant the ac 20
> 
> i like the agni motor but i feel tht a peak power of 25hp isnt quite high enough
> 
> ...


They've measured peaks between 35-40hp with higher voltage and the reinforced armature.

There are quite a few bikes that have dual agnis, look up "ttxgp" and "agni" on google. The Mavizen, Agni, Electricracebikes.com and Jozzer's bike have 2 motors on them.


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## appleseed (Sep 12, 2010)

i like dc motors but every website i find bout dual agnis just states tht the bike has them

it never says how they are set up: dual chains too? motors in series? parallel? how are they connected in sync? it looks like no can tell me how the 2 motors run as one


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## Evilsizer (Jan 25, 2010)

might want to check out this motor but is 5k rpm max going to be enough for you.
http://currentevtech.com/Drive-Syst...lers/37KW-BLDC-Motor-and-Controller-p174.html

37Kw = 50HP Peak
15Kw = 20HP Constant
230Nm = 169.64 Ft. Lbs, Peak Torque 
57Nm = 42 Ft. Lbs, Constant Torque
Weight 13 kg = 28.66 Lbs

or see if you can fit this one in
http://currentevtech.com/Drive-Syst...lers/55KW-BLDC-Motor-and-Controller-p175.html

55Kw = 75HP Peak
22Kw = 29.9HP Constant
250Nm = 184.34 Ft. Lbs Peak
84Nm = 61.95 Ft. Lbs Constant
Weight NA

or maybe this one even..
http://currentevtech.com/Drive-Syst...lers/40KW-BLDC-Motor-and-Controller-p166.html


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