# electric motorcycle?



## jason41987 (Jan 23, 2012)

hey everyone.. its almost motorcycle time now.. and i was thinking if build an electric motorcycle...

originally i had considered using a hub motor, but i looked at the best hub motors out there and at best, under no load with a 20 inch wheel size and 96 volts id still only get 55mph.. and thats without the weight of the bike and rider

so my idea is to get a small 32lb electric motor.. seen one for $550 that was 21hp peak, 11hp continuous which would be plenty.. and i could simply use a pulley or sproket on the motor and rear wheel to get the RPMs i need to comfortably ride at highway speeds... i think a 100a system would be sufficient... 72 volts, 100amps, six 12v 150ah batteries should probably get me a 50-60 mile range? sound right to anyone?

if i have room left over.. which i should if i removed, or somehow reused the fuel tank i could install a small 110v charger with concealable power cord to recharge while away from home.. and have a 220v circuit and charger at home in my garage

i was thinking maybe something like a honda CB350 with blown, siezed, or worn out engine as a donor.. or maybe an early 90s nighthawk..

so anyway.. i was looking at the length, width, height, and weight of various deep cycle batteries.. and well... im not sure if they would all fit... the width of these suggest a single row of batteries... but i would need to fix about six 12v batteries into this thing.. seems capacity is going to be kind of low and leave zero room for range extension...

i had the idea of possibly using a PEM cell which i would have to make from scratch (chemistry/physics/engineering background) but even making these would be rather expensive...

so... anyone make an electric motorcycle in here? what sort of performance did you get and which parts did you use? im also accepting any advice... and since i intend to move to a snowless part of the country, i would be getting more use out of an electric motorcycle than any cars i own right now.


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## esoneson (Sep 1, 2008)

jason41987 said:


> hey everyone.. its almost motorcycle time now.. and i was thinking if build an electric motorcycle...
> 
> originally i had considered using a hub motor, but i looked at the best hub motors out there and at best, under no load with a 20 inch wheel size and 96 volts id still only get 55mph.. and thats without the weight of the bike and rider


Perhaps you missed:

http://www.enertrac.net/

Eric


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## jason41987 (Jan 23, 2012)

i dont trust the posted specifications and performance for those motors.. if its 10rpm per volt, thats 960rpm at the 96 volt maximum, an 18 inch tire has a circumference of 56.5 inches which means for every revolution itll travel 56.5 inches... 56.5x960 = 54,240 inches traveled per minute, x60 equals 3,254,400 inches traveled per hour which is 51.3 miles.... nowhere near 60+... 62mph if you use a 22" wheel but thats getting kind of large on the rear end...

so, the numbers just dont seem to add up with theirs


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## jason41987 (Jan 23, 2012)

i found some nimh battery packs, 24v each 5,000Ah, $40... i would need 60 of these, overall weight is much lighter than the lead acid packs, a lot safer in the event of a wreck, and $2,400 is much cheaper than most lithium packs.. anyone think of doing something like this for their electric vehicles?


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## Tedktis (Jan 20, 2012)

Please contact Len Nelson @ cyclepedia . com and tell him you need this released!!!;
http://www.cyclepedia.com/how-to-build-an-electric-motorcycle-manual/


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## frodus (Apr 12, 2008)

jason41987 said:


> so, the numbers just dont seem to add up with theirs


I've seen the enertrac motor go much faster than 55mph, they raced it around a track in 2009 in Mid-Ohio at the e-grandprix show. 32cells of lifepo4 and a kelly and a hubmotor.... it went pretty well. I might have some video on my youtube under frodus17... but look up enertrac, there's a ton more videos. It will take more than 96V.

Also, don't use lead. You won't get over 30 miles out of lead. If you want range, get lifepo4 or lipo. NiMH might be ok... but they have some rules when paralleling them and charging. Look at not just the battery but cycle life. Even with lifepo4, don't expect much over 50miles range unless you put down some dollars or use a larger frame.

I think you mean 5000mAh, or 5Ah for $40, not 5000Ah.

100A is sufficient for cruising, but you'll need 2-4 times that for acceleration. You won't like the performance with 100A. 

As far as the speed, you're a bit off. The *wheel *size for that motor is 18", not the tire. The tire size for that motor is 110/90 X 18. You forget that you need to add the tire thickness.

Tire Height 25.80" = 18 + [(2 x 0.90 x 110)/25.4]
so, pi*d = circumference, pi*25.8 = ~81"
960*81 = 77760in in one min
77760*60 = 4665600in/hr
4665600/12 = 388800ft/hr
388800/5280 = ~73mi/hr

A bit more than 51.3mph

If you want to get a decent motorcycle book, get "From Fossils to Flux" by my buddy Ted Dillard:
http://www.lulu.com/product/ebook/f...gContext=search_results/search_shelf/center/1
or
hardcopy:
http://www.lulu.com/product/paperba...gContext=search_results/search_shelf/center/2


And head over to elmoto.net, we're motorcycle guys over there... quite a few more with experience over there.

feel free to ask me questions, or head to my blog: www.evfr.net


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## jason41987 (Jan 23, 2012)

yeah.. i did mean to say 5,000mah... 5000ah would have to be about the size of a car... 

umm, well thats where my math was wrong on the hub motor, i was using the rim diameter... however, those results were still done with perfect conditions and a rather light bike, and the motor itself is about $1200... 

i think spending $550 on the EMC-R LS motor which is a 48v motor, 21hp peak, about 11hp continuous would probably work better for me.. its about 32lbs, and i can just use a sprocket on the motor to get the RPMs i need at the stock rear wheel.. or spend $825 for the PMAC-DS motor which is 12kw continuous, 30kw peak, up to 96v if i want a little more power... but either of those would save me hundreds i can use towards a better battery pack.. so i think i answered my own question about the motor

i still need to figure out what ill do about batteries.. 30 mile range is plenty for the bulk of my driving, and on the very rare occassions i go further i still have a gasoline truck... so i think ill save some money and go with a lead acid pack

hmm... tell me, what sort of battery pack would i need for a mere 10-15 mile range with lithium or nimh?... how many AH would i be looking at?.. if i could build a pack to get me even that much range, i could gradually add more as time went on, keeping the low intial cost down

anyway.. in my spare time, i have a small laboratory at my house that i use to test out and experiment with different battery and fuel cell technologies... so mostly im looking for a commuter, and something to use as a test bed for these other projects.


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## frodus (Apr 12, 2008)

All of those motor choices are good actually, so any way you go you're fine. You just get a little more room for batteries with a Hubmotor and you can sell the rear wheel/tire/sprocket on ebay and recoup costs. 

What is your top speed goal? 
What is your range goal?
What is your budget?

Lead is a good place to start if you're just wanting to build and test things out, and move to another pack after lead is dead.

With a somewhat light bike, you're going to get around 100wh/mile. Meaning you use 100Wh for every mile. Now, say you want 30 miles, you'd need 3,000Wh from the pack. With lithium, go about 5% over. For lead, go about 30%+ over (peukert and 80% DOD), so lithium you'd need something like 3150Wh in a pack, and with lead, somewhere around 3,900Wh. So for 15miles, I'd aim for 20 and put in a 2.1kWh pack of lifepo4, or a 2.6kwh pack of lead. Maybe shoot a little over, but that's up to you.

I wouldn't try to piecemeal the battery pack. Just get it all at once. Mixing old with new is a bad idea and unbalances a pack. Plus, your pack is only as strong as the weakest battery. Just save and do it all at once, whether it's lead or lithium. And never mix chemistries. If you want to do 84V, do it from the get-go.

So lets say you chose lead, and you aim for a 2.6kwh pack. Now, lets say you want to do ~72V, then 2600/72= ~36Ah. There are plenty of 36Ah batteries out there, in fact I have 12 of them in my garage right now from my first iteration. You can EASILY fit 6 of them in a bike. Maybe even consider some larger batteries, like D34 55Ah or D35 48Ah Optimas (or something similar). If you do get Lead, DO NOT GET FLOODED LEAD ACID. It will spill when you're turning or have the bike parked. Get SLA or AGM.

If you choose Lithium and a 2.1kwh pack and 72V, you get 29.16Ah.... so round to the next largest cell. You could use 3 10Ah headway's in parallel for 30Ah, or you could use a Calb 40Ah cell. Just watch out with your discharge rates. Make sure your continuous current is less than the Max continuous of the battery. For lifepo4, go in multiples of 4 if you can, 72V would be 24 cells in series. 84V would be 28 and 96 would be 32.


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## jason41987 (Jan 23, 2012)

well frodus.. your information helps a lot.. i will go with that 11/21kw motor for $550.. wont take me much to weld in a mount for it roughly where the old tranny used to be...

id like to be able to travel at highway speeds, which are 55 here.. but a little more is good for short bursts

so.. if i were go lithium, to get 30 mile range your math suggests i would need roughly a 66Ah battery pack at 48 volts?... the motor i spoke of was a 48v motor which seems plenty for primarily a commuter when im using a sprocket and chain... i might go lithium if i can afford it... or nimh, i like the optima batteries, they look cool.. but aethetics are last place for me...

i was actually thinking of assembling my own frame jig.. if i did it would allow me to build a frame around the motor and battery packs but still be able to maintain the style of what i would have used as a donor bike

if i dont do that, i was really liking the honda nighthawk idea as a donor, i looked a the frame of one of those and they do seem to have some width to them around the engine, and theyre fairly cheap to find used...


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## ga2500ev (Apr 20, 2008)

jason41987 said:


> i found some nimh battery packs, 24v each 5,000Ah, $40... i would need 60 of these, overall weight is much lighter than the lead acid packs, a lot safer in the event of a wreck, and $2,400 is much cheaper than most lithium packs.. anyone think of doing something like this for their electric vehicles?


That has to be 5 Ah right? So that's $40 for 120 Wh

As for being much cheaper than lithium, I think I'll have to call you on that. At that price the cost is $0.33/Wh. A123 gray market prismatic lithium are obtainable for $25 for a effective 50 Wh cell making the cost $0.50/Wh. For that same $2400 you can get 96 cells for a 4800 Wh pack. At the 100 Wh/mile quoted above this will get you close to 50 miles of range.

But here's the kicker. That pack has a max draw of over 20C. Organized as a 24S4P pack of effective 80 Ah cells, you can draw 1600 Amps out of it. In short you can drop the hammer when you need it.

The cells are just shy of 1 lb each. So those 96 cells + packaging will weigh in at right around 100 lbs, which is less than the weight of 2 lead acid batteries.

ga2500ev


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## jason41987 (Jan 23, 2012)

yeah.. already said i meant 5000mAh... i was really tired and forgot the M when i typed that...

do you have a link to those lithiums? i havent seen them, if 100wh/mile is accurate, .50/wh would mean $50/mile meaning $1k for 20 miles which is quite adequate


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## frodus (Apr 12, 2008)

Do some planning if you want to use A123 20Ah, they're greymarket that don't get 20Ah out of them, they're 18-19Ah cells, and require a bit of work to get them built into a pack. They're not plug and play like others are, so just be aware. Not saying they're not a decent choice, but they're not as simple as some people make them out to be.

I do agree that lithium is a better solution though. I mean, lets say you get 55Ah optima D34's @ $200 each, so $1200 for 6 and you'd get 3960Wh, but only be able to use maybe 70% of that, so 2772Wh. Lets compare that to lithium and you'd need to buy a 2.9kwh pack to be about the same as that ~4kwh pack of lead. At 72V, that'd be 40Ah. 40Ah CALB batteries are about $50 each, so 24 would be $1200. So for just about the same cost, you can get lithium. D34's weigh 43lbs each, so 258lbs of lead. Calb 40Ah weigh ~80lbs. A123, you'd need 48 cells, they weigh 480g each, so 1.06lbs, and weigh ~50lbs and give a much higher discharge rate, but they're still the same Wh pack and it'd cost ~$1200 plus cost of bussbars/connectors and a solid way to mount them. Basically you have 3 options, and they keep getting lighter, but go from easy, to more complicated (OPTIMA, CALB, A123)

Also, don't use 48V or you won't hit 55mph. I'd suggest doing 72V. volts = rpm, so the lower voltage, the lower RPM. Sure you can gear it, but you get a lot wider RPM range with higher voltage. Those motors run without issue at 72V.


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## jason41987 (Jan 23, 2012)

i have no problem running 72v if the motor can take it...

so.. using that motor, a relatively light frame, i would need 23 of those calb batteries to equal 72 volts, so lets say 24 for a nice rounded number... at 40ah i believe they are... total weight of the pack would be 75lbs, plus 32 for the motor comes out to 107... add a bit more for the controller, mounting hardware, recharger.. probably less than 150lbs for the weight of it all, total bike wouldnt weigh more than 300lbs... 

it would be lighter, more agile, physically smaller so the hardware could be concealed behind a fairing as long as there was suitable airflow to keep it all cooled down.. so just to cover everything, lets over-estimate the weight of it all and say 400lbs for the bike, 200 for me... 

at 72 volts, 40ah CALB batteries, what sort of performance am i looking at with this?

and how safe would this be in the worse-case scenario: a wreck... obviously flooded batteries would spill everywhere, all over me, probably all over my skin, eyes.. not good at all.. how would the lithium conduct itself in any sort of slide or impact?


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## frodus (Apr 12, 2008)

Always try to go in groups of 4, 23 is a PITA to find a charger or BMS for. 24 is a nice number with lots of options for BMS (if you chose to use one) and Charger.

For performance, the CALB would likely do 3-4C continuous just fine, so lets say 160A, and lets say they sag to about 2.9V, so that's 160A * 2.9V * 24 = ~11kW continuous. I know they'll pulse at higher currents, so lets say you pulse them to 6-7C, so 280A for 15seconds or less (you don't want to discharge TOO much out of these, they're medium/low discharge rate cells). That might sag to maybe 2.75V (give or take, so 280A * 2.75V * 24 = 18.5kW.... that's a really rough guestimate. The datasheet says they'll do a pulse of 400A for 10seconds, and that'd likely be something like 25kw, but I don't know what they say to, so it's just an estimate. 

Basically, it's a good fit for your motor, just put in the right current limits on the controller and stay within realistic limits of the batteries, and you should be good. If you really hammer these batteries, they won't treat you well. If you have some sort of monitor with a low voltage alarm (minibms, cell-log 8's) you will know when they're getting too low.


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## jason41987 (Jan 23, 2012)

yeah.. i was going to put a gauge on it to tell me how much juice is left in them.. an alarm in the form of a light would be sufficient...

im just wondering what this would get me for top speed and range with the CALB pack discussed... also, about how many kilowatts will this most likely take to maintain a highway speed?

while im using this bike as a daily driver for myself.. im also going to continue to work on and experiment with other battery and also fuel cell technology on the side... add it to the bike when i feel neccessary...


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## frodus (Apr 12, 2008)

I don't mean a pack State Of Charge meter, I mean a cell-level volt monitoring, meaning if any cell goes below a setpoint (say 2.6V) an alarm goes. You really need to monitor on the cell level. Monitoring pack state of charge isn't enough, you may have one cell that goes lower than the others when you twist the throttle. Minibms does this by causing the throttle to decrease when you hit that limit, which causes less throttle, which decreases current so you avoid that level. Even if you top or bottom balance, one cell will get there before the others, and if you run the pack too much, you'll hit the knee of the curve one one cell before the rest. Cell-logs cause an alarm to be triggered.

If you want to know top speed, it's not so cut and dry, you'll have to do the work because there are too many variables. I'd suggest using one of the many ev calculators (there's one for motorcycles if you search for it a little bit, in fact it's posted over at elmoto.net if you want to head over there like I was saying). That would estimate top speed and power required at XXmph.

here's one:
http://evmc2.wordpress.com/2011/03/04/the-elmoto-v2-0-data-sheet-lennon-rodgers-upgrade/
which is a modification of this:
http://sites.google.com/site/lennonrodgers2/emotoengineering


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## jason41987 (Jan 23, 2012)

hmm.. looking at similar weight bikes, with similar capacity lithium batteries theyre getting 60mph+ and 40 miles range.. not bad at all.. i can make that work for me quite nicely... could even use it to visit relatives that live quite a ways outside of town

however.. while im running the bike with this setup.. i think im going to work on an extended range option i could possibly remove the battery packs and replace with something else to allow me to travel on highways when im away from home which is why im doing a lot of research into fuel cell technology, stirling engines (about 3-4 moving parts) as well as metallic alloys that can convert heat directly into electricity by generating a magnetic field when heat is applied

with alloys such as these, mixed from common metals you have an alternative means (though not as efficient) of turning fuel into electricity without moving parts or the use of adding a generator and obviously a device such as this could use anything combustable as a fuel... so i could possibly have a liquid fuel tank and a gaseous fuel tank mounted to the frame in place of the fuel tank and run on hydrogen, propane, gasoline, natural gas, kerosene, ethanol, etc


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## frodus (Apr 12, 2008)

good luck, would love to see what you come up with. I'm going to finish mine and consider adding a 1kw gas generator converted to propane to help a little and charge in case of emergency.


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## jason41987 (Jan 23, 2012)

im curious.. how much energy would i need to sustain this bike at cruising speed so i would know just how much of an engine i would need to increase power...

ive been working on stirling engines to use as the focal point of a parabolic (sattelite dish shaped) mirror to focus sunlight onto it for energy.. one 15' mirror would be enough to power my house, cost me only a few hundred to build (as opposed to $20,000 for solar panels), and probably last me longer too

stirling engines are up to about 50% efficient in converting fuel to energy and if i could someway conceal the combustion chamber, insulate it with the ceramic youd use for a crucible for metal casting, less heat would escape into the air forcing more heat onto the combustion chamber... then the open air of the motorcycle would cool down the heatsink of a cooling cylinder, and a relatively small, almost completely quiet stirling would make all the energy i needed, run any fuel at an efficiency an ICE couldnt do, and burn any gaseous or liquid fuel depending on the fuel tank you install

however... my first choice would be to find a way of using this metallic alloy that converts heat directly into electricity (if it has a high enough enough efficiency in converting that fuel heat into energy) and then i would have a completely solid-state system (except for the electric motor and rear wheel of course)


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## frodus (Apr 12, 2008)

I just did the math here for someone else:
http://www.diyelectriccar.com/forums/showthread.php?t=71097

See if you can calculate it

Remember, the cd for a motorcycle is crap, so something like 0.5 for motorcycle, maybe another 0.5 for rider so maybe 1.0 total. Cross sectional area is something you'll need to calculate, but the principle is the same. Weight, Area, Drag Coefficient and Rolling Resistance (probably something about the same) are what you'd need.

I thought stirling had a fairly poor power-to-weight ratio?


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## Duncan (Dec 8, 2008)

jason41987 said:


> im curious.. how much energy would i need to sustain this bike at cruising speed so i would know just how much of an engine i would need to increase power...
> 
> ive been working on stirling engines to use as the focal point of a parabolic (sattelite dish shaped) mirror to focus sunlight onto it for energy.. one 15' mirror would be enough to power my house, cost me only a few hundred to build (as opposed to $20,000 for solar panels), and probably last me longer too
> 
> ...


stirling engines are up to about 50% efficient in converting fuel to energy 

Where did you get this number?

The only production stirling engine I have worked on (whispergen) was less than 11% fuel - electricity
Fuel to "energy" was 99%
Which was fine for a combined heat and power unit - not so good as a power source for a motorbike


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## jason41987 (Jan 23, 2012)

yeah.. thats the problem with stirling engines though.. its very difficult, if not impossible to find a good commercial engine, theyre pretty rare, and never got the attention a steam engine receives..

without a heat exchanger the efficiency is pretty bad, are you certain the engine you worked on had this feature?.. its similar to how steam engines that do not reuse waste heat and water have much poorer efficiency than those that do.. its a small part to a stirling engine, but important

also, for external combustion a steam engine HAS to be used.. it would be very very difficult (though cool if you could) to get a steam engine to fit on a motorcycle and not add 100lbs+... besides, could you imagine a wreck where your injuries from the physical impact are made worse by being soaked in the boiling water and high pressure steam from the tank?


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## Duncan (Dec 8, 2008)

jason41987 said:


> yeah.. thats the problem with stirling engines though.. its very difficult, if not impossible to find a good commercial engine, theyre pretty rare, and never got the attention a steam engine receives..
> 
> without a heat exchanger the efficiency is pretty bad, are you certain the engine you worked on had this feature?.. its similar to how steam engines that do not reuse waste heat and water have much poorer efficiency than those that do.. its a small part to a stirling engine, but important
> 
> also, for external combustion a steam engine HAS to be used.. it would be very very difficult (though cool if you could) to get a steam engine to fit on a motorcycle and not add 100lbs+... besides, could you imagine a wreck where your injuries from the physical impact are made worse by being soaked in the boiling water and high pressure steam from the tank?


_without a heat exchanger the efficiency is pretty bad, are you certain the engine you worked on had this feature?._

You mean a re-generator - yep got one
The WisperGen Stirling engine was world class - I don't believe there has ever been a similar sized Stirling engine with a higher efficiency

The problem with all Stirling engines is their "work ratio" 
Their maximum possible efficiency is set thermodynamically to about 40%
(similar to a steam engine) the problem is that the pumping side of the Stirling cycle is nearly as big as the power side - this means that all inefficiencies bite you really hard
Basically you have 10Kw of power and 9Kw of pumping to get 1Kw of output, 
But your friction and inefficiencies work on the 19Kw - and take their bite out of the 1Kw output

This is the reason steam engines use the Rankine cycle - it massively reduces the pumping work

The Stirling engines main advantage is simple - It won't blow up! - in their day steam engines were notorious for blowing up (very impressively)


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## jason41987 (Jan 23, 2012)

would you really trust even a modern steam engine not to blow up?... and even a small risk of a steam engine going bad is greatly amplified by the damage it would do to you if you were nearby... heck, often our household espresso machines still blow up from time to time...

i just dont think i could trust a working steam engine being that close between my legs.. it would feel like riding a grenade... and ive had a steam pipe break near me once.. burned me pretty bad so i know what that feels like

anyway.. im really interested in learning more about this allow, basically heat goes into it, electricity comes out of it with no moving parts, sort of like a piezo with pressure, theres no moving parts and obviously the less parts means the less chance of failure.. and no one likes a vehicle that doesnt work, so im really interested in these solid state alternatives to any sort of combustion generator for range extention... its just too bad a suitable fuel cell costs about as much as a new motorcycle


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