1986 VFR700F electric conversion

[safetypro10]

OK.

HD= Harley Davidson, they use an external transmission, about the size of a large breadbox. Shaft in and shaft out, ready for gears, pullies etc.

OK, If they electric motor is fine direct drive, seeing as how acceleration benefits from gear ratio, limiting top speed, for now (120V is another story). Your shooting around 5:1.

Let's change gears.

If direct drive is good, and torque is available at 0 RPM, would it better more efficient to have 2 smaller motors vs 1 larger.

I'm thinking 2 motors in the drive hubs instead of 1 in the chassis with chain drive. I would really like to make an ebike, but the engineer wants to make something futuristic also, ala the Suzuki Nuda?

I understand that taking an existing bike and retrofitting an electric motor will be OK for now. My commute right now is 35 miles one way and I would like a little breathing room as pushing an ebike does not appeal to me.

Larry

BTW, if I haven't said it, I think this is one of the best ideas ever, and can't wait to make my own or even see a marketable kit.

[frodus]

HD= Harley Davidson, they use an external transmission, about the size of a large breadbox. Shaft in and shaft out, ready for gears, pullies etc.

Gotcha. I heard a little about the Harley's. but do you really need 5-6 gears? because of the RPM range, you might only need 2 gears.... but its an interesting Idea. The whine of a motor at 4-5krpm is awesome :)

OK, If they electric motor is fine direct drive, seeing as how acceleration benefits from gear ratio, limiting top speed, for now (120V is another story). Your shooting around 5:1.

My ratio is 5.45:1 right now, might adjust to 5:1 depending on what 120V gets me :) It'l allow higher speed. But the thing about a controller, is that it controls power. It uses PWM to control the "average" voltage to the motor. at 25% throttle of 120 it might be putting out 30V average. Lets say the batteries can put out 150A at 120V max. thats 18kW of power. At 30V, that'd be around 600A on the motor side. There are caps inside that are in parallel with the battery, so when you switch ON, the batteries AND caps, they discharge in parallel. When you switch off, the caps recharge for the other 75% of the time, fairly slowly. Then repeat ON OFF ON OFF ON OFF. The motor smoothes out the ON OFF ON OFF, so it just looks like a ripple with an average voltage of ~30V. It converts power (although, youre max output voltage is limited by the pack voltage, it doesn't increase power or voltage, just regulates power).

If direct drive is good, and torque is available at 0 RPM, would it better more efficient to have 2 smaller motors vs 1 larger.

Nope not really. Its better to install a larger motor, than 2 smaller. Essentially adding copper and extra flux would benefit more inside one case, as the efficiency would only occur at one motor, rather than having 2 motors and the losses increasing. When you can't FIT a large motor in, 2 smaller is fine, but still, more lossy.

I'm thinking 2 motors in the drive hubs instead of 1 in the chassis with chain drive. I would really like to make an ebike, but the engineer wants to make something futuristic also, ala the Suzuki Nuda?

2 words. Unsprung weight. Those motors won't be lightweight, at least if you want to get some decent performance out of them. All that weight is unsprung, and when you go around a curve, you get extra gyroscopic effects.

I understand that taking an existing bike and retrofitting an electric motor will be OK for now. My commute right now is 35 miles one way and I would like a little breathing room as pushing an ebike does not appeal to me.

yeah, converting is good for me for now too, but an engineered electric bike would be best. 35 miles is doable, can you charge there? Lots of companies can get incentives from their state for installing a charging station... so maybe asking them would be a good idea. Tell them you only need 5Kwh of electricity a day. its around 7 cents here per Kwh, so thats 35 cents a day. I'm sure they'll allow it.

BTW, if I haven't said it, I think this is one of the best ideas ever, and can't wait to make my own or even see a marketable kit.

I'd love to offer a kit for this honda with lifepo.... we're working on refining the setup, then we'll get lifepo and blueprint the kit for others. Thanks for the feedback :)

[safetypro10]

Ok, the serious search for a donor with large battery area begins. I saw a 08 GSXR1000 donor, but they wanted $1000. Maybe a slightly older bike with a dead/blown engine.

Keep up the good work. Was looking a LI batteries, but I can't seem to find a "package". Are you making your own packs for 96 or 120 V?

I really want something modular so I can fit as much power as possible in the frame, so flexibility may be important.

Is there a manual/guidebook for the engineering oriented so I can read how to install/wire/organize the bike?

Again, good job, lead on.

Larry

[frodus]

Ok, the serious search for a donor with large battery area begins. I saw a 08 GSXR1000 donor, but they wanted $1000. Maybe a slightly older bike with a dead/blown engine.

I'd avoid picking a bike first. In hindsight, i'd have chosen a slightly wider frame that can fit more batteries inside. V fours are nice engines, but the inline 4 are wider and allow more batteries inside.

First chose a budget, as its going to define the limts of the project. Next, define your range NEEDS (not wants), and speed NEEDS (not wants). Then look around for what it would cost for the system (battery,motor,controller, gauges). Calculate the weight/volume of the batteries and what the weight would be and if its resonable. Then see what kind of volume you'd need. THEN you chose a bike to convert based on the budget remaining and the volume/weight requirements of the system. (I'm an EE, so I figured out an efficient design process). Sure you could get a huge bike that handles like poo and fill it with 6grand worth of lifepo batteries, huge motor and controller.... but do you NEED that to meet your goals?


Lead is cheaper but heavier but allows for higher amps (more torque). Lifepo is more expensive but 1/3 the weight, and can't handle the amps that lead can. You would have a VERY hard time getting over 40 miles with lead though.

Keep up the good work. Was looking a LI batteries, but I can't seem to find a "package". Are you making your own packs for 96 or 120 V?

My pack isn't lifepo, they're AGM's (lead). I've got 10 12V 28Ah batteries in series and I'm making my own pack, battery balancing and charging system.

Lifepo doesn't come in preassembled packs, but they're not hard to make. Right now 20Ah batteries are about 37 bucks, 40Ah batteries are about 68 bucks, 60Ah are 102 bucks. If you needed a 6.5Kwh pack (100Wh/mile times 60 miles is about 6k plus extra for inefficiencies), and you used 40Ah cells you'd need 50cells in 2 cells in parallel, 25 of those in series to get about 82V nominal at 80Ah. 90 cubic inches (roughly) a piece, times 50 is 4500 cubic inches. About 2.6 cubic feet if they're all crammed together with no space in between, estimate more like 3-3.25Cu-ft. Thats about the inside size of a large mini fridge just for batteries. 50 cells of the 40Ah is 3400 bucks, no charger, no battery management system (REALLY important with lifepo). Then add to that the size of the motor, a controller and a charger.

I really want something modular so I can fit as much power as possible in the frame, so flexibility may be important.

get as small batteries as you can (they fit easier) and design a battery rack that will allow for several different ways to fit the batteries in the footprint. We built my first battery tray with lifepo in mind, and threw lead in there for now.

Is there a manual/guidebook for the engineering oriented so I can read how to install/wire/organize the bike?

just my website, EValbum (for other bikes and personal websites) and manufacturer datasheets for controllers and motors and batteries/BMS/chargers. Its really bleeding edge, so you're going to have to research alot on your own. Don't just go on EV forums and say "so I want to build an EV", they'll just tell you to use the search button. When you have researched a little, know budget and have gotten a better idea of cost and complexity you can state "so, this is my plan, any comments".

[steven113]

sounds like a great project to me! keep it up!