I've been lurking for a while, and finally got a start on my electric motorcycle project. I figure I will document my (slow) progress here.
I'm a mechanical engineer working in the controls industry, and lately I've felt the need for a new project that will stimulate my need to design/build things. I screw around with 3d printing, RC cars, and real cars (hondas and subarus mostly).
Why an electric motorcycle?
- I don't have room to get another car to mess around with, so I want to get a motorcycle.
- I've been amazed by the performance offered by the lithium/brushless combos that are becoming ubiquitous in the RC world
- It only needs to be practical enough to commute 20 miles per day, otherwise it's a toy.
- I like the idea of being able to hoon around on it at low-ish speeds without annoying people.
- I can get some decent performance out of it without spending a ton of money (budget around $5000).
- I helped with a much more tame conversion a few years ago at school (sub-40mph Etek/Alltrax/batteries I don't remember on an old GS550 frame)
- I can feel less-bad about the environmental impact of my modified subaru.
Basic goals before I dive into the details:
- Easy to register for road use. If the donor bike has clean paperwork, I basically just tell the DMV what I started with and check "electric" instead of "gasoline" as the fuel type.
- Small: Designed around a Ninja 250, but open to use whatever entry-level full-fairing sport-ish bike I can scoop for cheap on craigslist.
- Lightweight, low center of gravity
- 25 miles will get me to work and back, but I can charge at work if I completely screwed up my range calculations.
- Highway-capable, geared for 70-75mph top speed: I'm not planning to ride this thing on the highway, but I'd like to not die if I have to do it for an exit or two.
- Strong acceleration at low speeds. I'd love it if wheelies were possible, but it at least needs to be faster than most things in the 250cc range up to 40-50mph.
I'm building the bike in a few steps to allow me to work out issues before I spend too much money on things that aren't going to work:
Phase 1 - Battery and Charging system.
To get the bike going, I'm building a smaller (2.6 kWh fresh off the charger) pack that will be expanded once I have it working well enough to ride around and decide I want more range. Also I can't really do any motor/controller testing without the battery pack, so this only makes sense as a starting point.
I'll be running a 20s4p pack of SPIM08HP lipo's housed in a case made of 3d printed ABS. If the specs aren't complete BS, the cells are 8Ah rated at 25C discharge/8C charge. All of the cells I've cycled seemed right around that 8Ah mark, so our total capacity seems pretty believable at least. I'm pretty sure these were salvaged from a chinese hybrid electric bus. If the 25C rating is accurate, the pack should be capable of kicking out 800 amps, which is more than I'll ever really need to be honest.
Messing around in Onshape, I've more or less figured out the overall shape and size of the pack. The cells will be held together with 3M tape, and the crimped area around the pouch will locate the cells in the enclosure. I've got plenty of room for BMS wiring, temp probes, pretty much whatever. With the enclosure it's a bit over 14in long, 11.5in wide, and about 9in tall. Should end up right around 60lbs assembled pack weight.
I'm doing experiments with smaller 4s and 2s2p packs to work out any issues I might run into with the battery case construction and securing the cells. They'll most likely end up running my daughter's power wheels for a chunk of the summer.
Currently, I'm just using my hobbymate elite to charge/cycle a few cells at a time, but I'm planning to bulk charge with either an S1600 or S2500 from BMSbattery. At home I will be charging from a 120v outlet, but at work I have access to 220v for faster charging. J1772 capability falls firmly in the "I want it but we'll worry about that later" category.
Phase 1.5 - Battery Management and monitoring.
For battery management, I'm going to take a swing at using a one of the several arduino mega's I've got kicking around and a few multiplexers to monitor individual cell voltages. Cell balancing will be handled using a relay (solid state or otherwise) to connect the 4 cell module to a beefy resistor. If I run into problems making it work on the smaller packs, I'll go with an off the shelf solution.
Once the cell voltage data is in the arduino, I can either send drive a simple display right off the arduino, or I can pass it to a raspberry pi if I want a bigger/nicer screen.
Phase 2 - Powertrain
Once I have the battery pack together I can start playing with the motors and controllers.
I'm going to attempt to run a pair of water cooled 50kv sensored MP12090's (the same ones you'll find from Alien Power Systems, Ehobbypower, FRCHobby, etc) with a Kelly KLS7230S for each of them. I'll be running a primary chain with a slight reduction, with the goal of locating the countershaft/drive sprocket in roughly the original location and using more "normal" rear sprocket sizes. The motors will share a single, longer shaft. I'll attempt to use the original radiator from the donor bike, but the cooling system really is not that challenging to figure out.
The motor mounts and primary are going to be made out of some aluminum L-channel.
At the maximum rated current, these guys should kick out around 30-35lb-ft of torque each if the specs are not complete BS, so geared to hit 75mph we're looking at more than 250lb-ft to the tire, which should be plenty of fun to rip around with.
Phase 3 - Donor Bike
I love the styling of the Ninja 250, and was pretty comfortable on the last one I sat on, so that makes the choice obvious, but really I'm open to any full-fairing entry-level sporty bike I can get for cheap on craigslist. I'd really like to stay full fairing for both aero as well as the bike looking much cleaner with all of my electrical nonsense covered up.
This is where the general maintenance, teardown, and actual conversion will happen.
Phase 4 - Nice-to-Have's
So once it's working and sorted out, we've reached the "nice to haves". These are mostly things to make it more useful like the addition of J1772 charging and a big pile of additional batteries to bring the total pack size up to 5-6kWh, which should be enough to bump the range up to 60 miles or so.
I'm a mechanical engineer working in the controls industry, and lately I've felt the need for a new project that will stimulate my need to design/build things. I screw around with 3d printing, RC cars, and real cars (hondas and subarus mostly).
Why an electric motorcycle?
- I don't have room to get another car to mess around with, so I want to get a motorcycle.
- I've been amazed by the performance offered by the lithium/brushless combos that are becoming ubiquitous in the RC world
- It only needs to be practical enough to commute 20 miles per day, otherwise it's a toy.
- I like the idea of being able to hoon around on it at low-ish speeds without annoying people.
- I can get some decent performance out of it without spending a ton of money (budget around $5000).
- I helped with a much more tame conversion a few years ago at school (sub-40mph Etek/Alltrax/batteries I don't remember on an old GS550 frame)
- I can feel less-bad about the environmental impact of my modified subaru.
Basic goals before I dive into the details:
- Easy to register for road use. If the donor bike has clean paperwork, I basically just tell the DMV what I started with and check "electric" instead of "gasoline" as the fuel type.
- Small: Designed around a Ninja 250, but open to use whatever entry-level full-fairing sport-ish bike I can scoop for cheap on craigslist.
- Lightweight, low center of gravity
- 25 miles will get me to work and back, but I can charge at work if I completely screwed up my range calculations.
- Highway-capable, geared for 70-75mph top speed: I'm not planning to ride this thing on the highway, but I'd like to not die if I have to do it for an exit or two.
- Strong acceleration at low speeds. I'd love it if wheelies were possible, but it at least needs to be faster than most things in the 250cc range up to 40-50mph.
I'm building the bike in a few steps to allow me to work out issues before I spend too much money on things that aren't going to work:
Phase 1 - Battery and Charging system.
To get the bike going, I'm building a smaller (2.6 kWh fresh off the charger) pack that will be expanded once I have it working well enough to ride around and decide I want more range. Also I can't really do any motor/controller testing without the battery pack, so this only makes sense as a starting point.
I'll be running a 20s4p pack of SPIM08HP lipo's housed in a case made of 3d printed ABS. If the specs aren't complete BS, the cells are 8Ah rated at 25C discharge/8C charge. All of the cells I've cycled seemed right around that 8Ah mark, so our total capacity seems pretty believable at least. I'm pretty sure these were salvaged from a chinese hybrid electric bus. If the 25C rating is accurate, the pack should be capable of kicking out 800 amps, which is more than I'll ever really need to be honest.
Messing around in Onshape, I've more or less figured out the overall shape and size of the pack. The cells will be held together with 3M tape, and the crimped area around the pouch will locate the cells in the enclosure. I've got plenty of room for BMS wiring, temp probes, pretty much whatever. With the enclosure it's a bit over 14in long, 11.5in wide, and about 9in tall. Should end up right around 60lbs assembled pack weight.
I'm doing experiments with smaller 4s and 2s2p packs to work out any issues I might run into with the battery case construction and securing the cells. They'll most likely end up running my daughter's power wheels for a chunk of the summer.
Currently, I'm just using my hobbymate elite to charge/cycle a few cells at a time, but I'm planning to bulk charge with either an S1600 or S2500 from BMSbattery. At home I will be charging from a 120v outlet, but at work I have access to 220v for faster charging. J1772 capability falls firmly in the "I want it but we'll worry about that later" category.
Phase 1.5 - Battery Management and monitoring.
For battery management, I'm going to take a swing at using a one of the several arduino mega's I've got kicking around and a few multiplexers to monitor individual cell voltages. Cell balancing will be handled using a relay (solid state or otherwise) to connect the 4 cell module to a beefy resistor. If I run into problems making it work on the smaller packs, I'll go with an off the shelf solution.
Once the cell voltage data is in the arduino, I can either send drive a simple display right off the arduino, or I can pass it to a raspberry pi if I want a bigger/nicer screen.
Phase 2 - Powertrain
Once I have the battery pack together I can start playing with the motors and controllers.
I'm going to attempt to run a pair of water cooled 50kv sensored MP12090's (the same ones you'll find from Alien Power Systems, Ehobbypower, FRCHobby, etc) with a Kelly KLS7230S for each of them. I'll be running a primary chain with a slight reduction, with the goal of locating the countershaft/drive sprocket in roughly the original location and using more "normal" rear sprocket sizes. The motors will share a single, longer shaft. I'll attempt to use the original radiator from the donor bike, but the cooling system really is not that challenging to figure out.
The motor mounts and primary are going to be made out of some aluminum L-channel.
At the maximum rated current, these guys should kick out around 30-35lb-ft of torque each if the specs are not complete BS, so geared to hit 75mph we're looking at more than 250lb-ft to the tire, which should be plenty of fun to rip around with.
Phase 3 - Donor Bike
I love the styling of the Ninja 250, and was pretty comfortable on the last one I sat on, so that makes the choice obvious, but really I'm open to any full-fairing entry-level sporty bike I can get for cheap on craigslist. I'd really like to stay full fairing for both aero as well as the bike looking much cleaner with all of my electrical nonsense covered up.
This is where the general maintenance, teardown, and actual conversion will happen.
Phase 4 - Nice-to-Have's
So once it's working and sorted out, we've reached the "nice to haves". These are mostly things to make it more useful like the addition of J1772 charging and a big pile of additional batteries to bring the total pack size up to 5-6kWh, which should be enough to bump the range up to 60 miles or so.