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[mKlRivPwner]

Hey everyone.  I'm new to EV's and Motorcycles.  Although I'm been working mechanically on cars for more than 15 years.  That's quite some time considering I'm 25.  I decided to build my own Electric Motorcycle as both a Commuter Vehicle and a Fun Ride.

My goals:
80 mph top speed (Freeway usable, not just feasible)
125+ mile range on a full charge
72 Volt AC Motor
Shaft driven
< $7,500 Including the donor bike

I have no problems with the "traditional" modifications (frame, gearing, parts mods, even the fiberglass bodywork), but I'll need some help with the electrical aspects.  Specifically, I'll need suggestions on what components to look for.

[frodus]

125miles is going to be damn near impossible with your budget. For 125 miles range, and a 125wh/mile average (which is average for most electric motorcycles), you'd need 16-17kwh onboard. IF and I REALLY MEAN IF you could even FIT all those batteries in the motorcycle (which would also be damn near impossible), it'd cost you at the very least 8grand for batteries that have a low volume/high energy density. Thundersky batteries won't cut it, and neither would headways. You'd have to get something like Kokam Lithium batteries, and they're not cheap.

(note: I worked on the MotoCzysz E1pc motorcycle project and we had a really really hard time fitting in ~15kwh of batteries in the motorcycle, and it was NOT cheap and it was very complicated).


That being said: 80mph should be doable with a good 72V AC setup, but I'd go higher voltage than that, closer to 84V. Expect to spend about $3200 on just the motor/controller setup: http://www.electricmotorsport.com/store/ems_ev_parts_motors_ac-induction.php
There's really nothing else on the market in AC at this time, not for motorcycles.

shaft driven depends on your motorcycle....... and your ability to machine parts/gearbox and get the gear ratio correct (from motor to wheel).


My suggestion?
lower your range requirements in half. You don't NEED 125miles, you WANT 125miles.

If you cannot decrease that range, then double/triple your budget.

[skadamo]

Welcome to the forum! I'm sure you will find some good information here. Looking forward to seeing what you put together...

[mKlRivPwner]

Thanks for the welcome and the... umm... erhm... "encouragement?"

You're right, I don't NEED 125 mile range, but what I'm really trying to do here is prove that Electric Motorcycles can be built for something more than a cross city errand.  The top end builds I've seen and researched on have maximum practical ranges of around 50 miles.  Now that's enough to get from home to work and back, but what about if I need to go by the pharmacy or pick up lunch?  Now I have to carefully calculate how hard was the wind blowing, will it be doing the same on my way home, how bad is traffic, did my batteries have full juice, how much did I use...

I was figuring, in a typical day trip, an individual could easily spend 1.5 hours driving.  Averaging 70 mph (I don't condone speeding, but flow of traffic, more often than not necessitates it) that's 105 miles.  Then there's a buffer zone (20 miles).

I've been looking at the LiFEPO4 batteries.  Not too bad of a price, considering.  Pretty small footprint too.  Granted I didn't expect to require quite that much juice.  Even still, if I need that much, maybe I'll back down the range for V1.0 and add large batteries and a CVT later on.

I'll continue any further posts in a new topic under Tech.

[frodus]

Sorry about the "seemingly" rough encouragement.... My initial aproach with new people that come is to be completely honest and up front about the requirements to be able to get that range/speed. I'm a realist.

That being said, I think the project is doable, completely doable, but some things need to be considered.

The first is budget. I think for what you want it needs to be a little higher.

second is weight. If you have to put more kwh onboard, you'll need more room, and it'l be heavier. If you can afford a higher density cell like Kokam, you should have an easier time fitting batteries onboard and it'l be more energy dense and be lighter.

third, these vehicles aren't for day trips. They're for comuting or racing. They're not long range vehicles and won't be until we can cram more energy onboard..... so there's also something realistic to consider. Maybe you could get a 1 cylinder engine and make a hybrid? Thats what the car manufacturers are doing.... because bat tech isn't what they need for long range.

Concerning a CVT.... It'd probably hurt range more than help it, they're fairly inefficient. You could design a gearbox using off the shelf transmission parts and design your own in a small footprint. It'd be a whole lot more efficient, but less efficient than direct drive.

I'm an engineer, so when people overengineer things, I ask "why".... your responses are good, but range = deep pockets and I wanted you to know that.

[mKlRivPwner]

Thanks Frodus.
I've seen you all over the forum and you really know your S!*#.

I want to avoid the hybrid idea for simplicity sake.  I'm no engineer.

Just seems like Technology and Design in the automotive world gets itself into a loop.
"The cars and motorcycles aren't being mass produced because technology is too expensive."
"Technology is too expensive because it's application specific and the applications (cars and motorcycles) are not mass produced."

[frodus]

yeah, I tend to get around a little (here, elmoto, endless-sphere and diyelectriccar).... I guess thats what happens to hyperattentive people (form of ADHD)....I eat, breath and sleep electric motorcycles I figure I can at least share what I've learned.


Its not really the drive systems as much as it is batteries.... major breakthroughts have happened the past few years, but it takes a few years to convert those breakthroughs to mechanical production processes to mass produce batteries, get licensing, get investors, get buyers.... they don't care about DIY people. We'll see stuff more available soon.

For now, ranges are somewhat limited, but there are batteries out there (like kokam) that have a high density. The availability of electric power is the great thing though, the infrastructure is as wide reaching as water supply. Can't get gas on every corner can you......

[mKlRivPwner]

You can around here (Central Pennsylvania).  But then again, this entire area is huge on cars, motorcycles, and the like.  What with every major freight rail company running through the area, Harley having a production plant in the county, proximity to auto imports and American made auto plants, major transit stop offs (Washington DC, Baltimore, Harrisburg, New York) and the list goes on.

I guess that's what you get for living in a "megalopolis".  But I don't mind it so much.  I'm always no more than an hour from some city, and we still have plenty of gorgeous country-side to see.  And with fall coming up, the Appalachians will be beautiful.  It's my personal opinion that everyone should drive MD State Route 220 at least once.  I especially endourage you to do it around early-mid October as the leaves change.

I think I met a resolution for my battery dilema.

V1.0 LIFEPO4 batteries 100mAh and deal with the range shortage.
As technology (and my bankroll) builds to meet consumer needs, add bigger high capacity batteries.

And I think a simple light weight mechanical gear box will be possible with gear ratios ranging from 9:1 reduction through 4:1 reduction on a DC motor running at 7.68 Volts with regen.  The electronics and controllers of anything else will add too much weight.

[frodus]

100mAh?

you mean Ah? mAh would be unuseable for an EV.... hehe

Even 100Ah batteries are going to be tough to fit in a bike.... really tough. Especially in a conversion. I know the motoczysz bike had over 14kwh onboard, but the frame was built for holding batteries, many bikes you'll find aren't made to fit some of the types of batteries you'd be using.

Also, If you want range, I'd do away with the gearbox, you won't need it for 80 or so mph. It'l only add inefficiency and decrease you're range. I've done the calcs with MotoCzysz (helped with their E1pc motorcycle) and gearing marginally helps the amperage of the motor, but the inefficiency hurts range. They did the calcs, and unless you're going over 100mph (in which case you'd need a higher HP motor than is available off the shelf), then you don't need a transmission. The power band is wide enough. We looked at some graphs on some dyno software to see what a 2speed would do.... and we didn't really need it.

7.68Volts isn't that much, you'd be going about 5mph with most of the motors out there. If you meant 76.8, then you'll need more voltage than that. Start thinking 96V or more. I'll be running 102V and should hit 80 no problem.

You'll add more weight/volume with the gearbox than you would with a couple extra batteries. If you want range, make the thing as light as you can, put an efficient motor/controller in there and cram as many batteries in there. Make it more aero and strip some of the not needed stuff off of it and get some low rolling resistance tires.

[Bogan]

thats pretty intersting that a gearbox would impair the performance of the motoczysz, its a 20odd kW race bike isnt it?

[frodus]

Its inefficient.... you're adding mechanical loss, and mechanical drag on the motor... every little bit counts around a track like that. With their gen 2, it'l have one larger motor and a 2-speed gearbox of some sorts.... but they'll have much more dense batteries, so they aren't scraping by on the kwh onboard.

My point is, you don't need it for 80mph, but a superbike like the E1 WOULD need it to get to much higher race speeds.

Also, its not 20kw, its 14-15kwh. I helped build their packs.

[mKlRivPwner]

Sorry.  Fat fingered that one.  100Ah and 76.8 Volts.
I'm starting to think just to get started I can get 60 Ah batteries  And when I get the kinks worked out adding another set of 60Ah in parrallel.

As for the Transmission, I was thinking 3 speed with some pretty big gearing differences.  6:1, 4:1, 2.5:1 (9:1, 6:1, 4:1 if I can get an AC motor).  Even that wide of a range will hinder motor performance?