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[TurnNBurn]

Hello all! I just picked up a Honda CBR that was in great condition (engine is in good condition too!) Anyways, I'm looking to sell the mechanical parts and build it into an EV bike. I have a few questions.

I've been doing some research, and I see Electricmotorsports.com seems to be a good place to buy parts. I have questions about motors. First off, what's the difference between a brushless permanent and brush type motor?

Second, I'm not a speed freak, but I'm in Vegas and highway travel is almost a must because of where I'm located. What specs should I be looking for to get me up to 75mph wih a range of about 45 miles? Do I need to be concerned with horsepower ratings at all?

[Bogan]

Brushless require more complicated motor controllers, but are lower maintenance motors. I won't comment on the power/weight/cost of each, cos you'll be finding that out more accurately when you have a look around for the best motor for you.

75mph, is, at a guess up between 15-20kw. So you'll have to get a motor that is rated for this continuously, not just peak, the peak rating is useful when accelerating, so make sure that is 30kw or more, and that your controller is rated for the peak too. You'll also have to ensure you battery pack is large enough to output that power. For pack size, say 20kw for 40mins (to get the range at 75mph + a bit extra for acceleration), is 13kwHr.

The big questions are, is how much are you looking to spend? How mechanically proficient are you? How electrically proficient are you?

[TurnNBurn]

The big questions are, is how much are you looking to spend? How mechanically proficient are you? How electrically proficient are you?

I'm quite proficient mechanically, but not electrically. I've pulled a few car engines and transmissions and have done a lot of work on cars. This will be my first motorcycle job. To start I didn't want to reach the 75 MPH/45 mile goal, I wanted to start with a motor and powerplant that would potentially allow me to upgrade the batteried later on down the line.

Cost is always a factor, but I'm not buying the parts all at once. I wanted this to be a weekend project thing that I can buy parts for monthly and keep adding on to it. I just need to know what I'm looking for. Since the bike was in such great shape, the engine is in great shape and I was going to rebuild that and possibly sell it. I'm also tempted to reinstall the gas engine once it's rebuilt, but I'd really like to make the EV conversion work.

[frodus]

what kind of budget?

Do you want regenerative braking?

what top speed do you need (not just 75mph, you'd likely want more)?

What range at 75mph? what range at 45mph?

Can you reduce the range requirement by charging at work or something?

[TurnNBurn]

My "drive" to work is only about 5 minutes, and I usually walk to work. But with an electric bike I would probably ride it to and from, but I wouldn't be able to charge it at work. So that's not an issue.

Around town everything is out on the far side and usually requires sustained speeds of 45 mph. There's usually 2 ways to get to where I like to go. I can drive for 30 minutes at 45mph or take the highway at 75mph and be there in 10-15 minutes.

I don't think I'd want regnerative braking. I haven't looked into that at all yet.

As for the budget, I didn't want to dump a whole lot of money into it since it was just a fun project. I was hoping I could sell the engine and other miscelaneous parts from the bike and make back some money to increase the budget. But at this point I just want to weight the costs for all of my options.

[frodus]

regen = engine braking.... so consider it. You'd have to use brushless (AC or BLDC) or use a brushed PM motor with a regen controller. If it's not a huge thing, get a 6.7" forklift motor with gobs of torque. I wouldn't really mess with the brushed or BLDC Mars unless you get the double stack BLDC. You need a bit of power to get to 75mph. You will likely also need a higher voltage than 72V.... like 96V.

Basically for a range of 40 miles, you could do it with lead, but you'll get less and less out of the pack over the next year. I'd stick with lifepo4. You'd also need a really large and heavy pack. For a 40 mile range, and lets assume ~100wh/mile, you'd need about 4kwh of useable energy. With lead, you'd need over 5kwh. With lifepo4 you might need right around 4kwh. Going with GBS system (with charger and BMS with LCD) you're right around $3200 or just batteries for ~$2000. Going with CALB, you're at about $1700 without BMS or charger.

Motor and controller is going to be in the 1500-3000 dollar range, depending on what you get. You could go with AC Induction like I did, but that'd set you back a bit over $3k. You could do a BLDC/PMAC motor like the mars double stack for ~$850 then a matching controller with enough power to get you to 75-80mph for another $800 for a small controller or $1400 for a higher power one. Charger is going to be at least $500 new. Then chain, sprocket (you'll need a new rear sprocket and some front sprockets), cables, fuses, contactor, DC-DC converter for your 12V stuff (another $100-200).

So it's not cheap, but it can be done for under $4k if you really scrounge for stuff and bargain hunt. My first version of my bike used a surplus $250 forklift motor and a cheap cheap brushed controller and some used UPS batteries and got about 65mph max and maybe 15 miles at 45mph or less and cost me under $1000 without the cost of the bike.

[TurnNBurn]

Thans for that info. That helps a lot. I'm looking to start small, maybe with basics and build up from there. So if that means getting a motor that only gets me to 45mph, so be it. In the future I'll upgrade. Right now I'm looking on craigslist for forklift parts and golf carts. I'm not finding much. You'd think vegas would have anything you could want. But mechanical bits are scarce here it seems.

One quick question about the brakes. Can't I keep the stock brakes on it, or do they require the engine to be running in order to be used? I'm in the process of stripping the bike and want to know if I should leave these on or take them off.

[frodus]

Don't use a golf cart motor. They're usually meant to be coupled to a differential and don't have the shaft end bearing/plate and have a splined female shaft.... not great for a motorcycle unless you want lots of work. Use a forklift motor or something surplus, maybe a mars. Look secondhand if you can. Check out elmoto.net and evtradinpost.com

Stock brakes are fine. No requirement for engine braking usually. Most are independant hydraulic brakelines. Keep all brake and electrical wiring harness. sell/throw away the engine/exhaust keep the radiator or oil cooler in case you want water cooling later.... keep the rear sprocket for now.

let me know if you need anything, I've worked with a ton of people on getting them parts and I work with most budgets. www.emf-power.com

[TurnNBurn]

Don't use a golf cart motor. They're usually meant to be coupled to a differential and don't have the shaft end bearing/plate and have a splined female shaft.... not great for a motorcycle unless you want lots of work. Use a forklift motor or something surplus, maybe a mars. Look secondhand if you can. Check out elmoto.net and evtradinpost.com

Stock brakes are fine. No requirement for engine braking usually. Most are independant hydraulic brakelines. Keep all brake and electrical wiring harness. sell/throw away the engine/exhaust keep the radiator or oil cooler in case you want water cooling later.... keep the rear sprocket for now.

let me know if you need anything, I've worked with a ton of people on getting them parts and I work with most budgets. www.emf-power.com

That's good to know. I had the radiator in the "scrap to sell" box. Why would the radiator be something to keep as opposed to making some sort of air cooled system? Since it's a sports bike and I have all of the fairings, wouldn't air cooled be the way to go? Also, with keeping the radiator wouldn't I need some sort of fluid pump to circulate the coolant?

[Bogan]

The big questions are, is how much are you looking to spend? How mechanically proficient are you? How electrically proficient are you?

I'm quite proficient mechanically, but not electrically. I've pulled a few car engines and transmissions and have done a lot of work on cars. This will be my first motorcycle job. To start I didn't want to reach the 75 MPH/45 mile goal, I wanted to start with a motor and powerplant that would potentially allow me to upgrade the batteried later on down the line.

Cost is always a factor, but I'm not buying the parts all at once. I wanted this to be a weekend project thing that I can buy parts for monthly and keep adding on to it. I just need to know what I'm looking for. Since the bike was in such great shape, the engine is in great shape and I was going to rebuild that and possibly sell it. I'm also tempted to reinstall the gas engine once it's rebuilt, but I'd really like to make the EV conversion work.

Thats the better way to be, the electrical side of things is a bit simpler than the mechanical in these builds.

Be wary of feature creep, it generally costs more in time and money than just doing it properly to begin with. If you're sure you want a bike with high spec speed and range, then do the budget for that, and go for it if you can afford it. Starting with cheap parts may sound good in theory, but chances are the newer and better stuff you get later won't bolt straight in, and will require almost as much work again, as the cheap part conversion did.

[frodus]

That's good to know. I had the radiator in the "scrap to sell" box. Why would the radiator be something to keep as opposed to making some sort of air cooled system? Since it's a sports bike and I have all of the fairings, wouldn't air cooled be the way to go? Also, with keeping the radiator wouldn't I need some sort of fluid pump to circulate the coolant?

I'm just saying keep one of them for now. Air cooled motor is just fine (most motors you find will all be air cooled). I'm saying keep either that or the oil cooler if you want to water cool the controller later. Usually the controllers are tucked inside the fairings and don't get great flow. Right now I'm just using a custom finned heatsink, but I have the option to use a water cooled plate that I had made if the controller gets too hot. You may not need it at all, and 90% of builds don't.... but it doesn't hurt to save it now.

And I agree with Bogan. See if you can afford what you want, up front, even it it means saving a while. Buying cheap or small now, then upgrading is good if you can resell the stuff later... but things like batteries don't resell well, and motors wear and aren't worth as much later. You'll lose money in the end. It's what I did, and I managed to come out as a loss. batteries were a total loss when upgrading, motor I broke even, controller was returned to the place I borrowed it from.... but I lost money in the battery frame material/labor and the motor mount material/labor, charger, cables, fuses, contactor and chain.

[TurnNBurn]

Alright, sounds like good advice I shoud adhere to. I think I'll just stockpile money and get the desired parts first instead of upgrading.

[frodus]

Get batteries LAST, so you get some that are new and haven't been sitting while you do stuff.

Get motor/controller first and get it fit inside. When you get that done, start looking into batteries..... more might come on the market in the meantime.

[Bogan]

Good point on the batteries frodus, I'd add to that you still want to design with specific batteries in mind, to ensure you will have space for them and not end up with a hodge-podge of batteries stuck all over the show.

[TurnNBurn]

That was my overall plan. I was going to choose the batteries ahead of time so I know how much juice I'll have for distance, but I wasn't going to purchase them until I was almost done. At that time I figured maybe battery technology would have advanced enough to make them smaller and more efficient.