Senior Design Project
Hey Guys,
I'm a mechanical engineering student from UCF (University of Central Florida), my senior design project has been to build an electric sport bike, with the aim of making it cheaper, and having comprable (or better) range than the Brammo/Zero competition. Really a proof of concept - to improve market visibility to electric auto movement.
We've got an idea of where to start; Find a donor bike and use the frame/fork/wheels/brakes/etc and retro fit the electrical hardware into the bike, or use a donor bike frame as a starting point to build our own.
I've gotten some good advice from people, but I know this project is going to boil down to 3 things: the controller, batteries, and motor.
I've heard that Lead-Acid are easier and more affordable to work with, but the possibility of LiFeMgPO4 (or similar batteries) are tempting. Weight, physical dimensions, kwhr output will all be factors in the descision process.
As far as the controller goes I've been steered in the direction of the Alltrax 7245, although I'm seeing plenty of options from Alltrax; I'm just not sure where to start from.
Motors: I keep hearing about the Agni R95, although with a price of around $1400 this would eat up a lot of the total budget. I've seen other options like the Etek-r and the Perm PMG-132, I'm just not sure what the best bang for the buck would be.
One of the biggest issues I'm having right now is the battery situation; From what I've read so far, it seems like 72 volts is the sweet spot for operating voltage- that would mean 6 optima batteries.
Our team has a estimated budget of $3-4k USD. We have access to machine shops and are all mechanically inclined.
What are some good sources of info (other than this website) to help me educate myself in the finer aspects of a project such as this. In addition, since I will most likely have to buy most of components from the internet, where are some good places to order from. Thank you for your time,
UCFdave
I'm a mechanical engineering student from UCF (University of Central Florida), my senior design project has been to build an electric sport bike, with the aim of making it cheaper, and having comprable (or better) range than the Brammo/Zero competition. Really a proof of concept - to improve market visibility to electric auto movement.
We've got an idea of where to start; Find a donor bike and use the frame/fork/wheels/brakes/etc and retro fit the electrical hardware into the bike, or use a donor bike frame as a starting point to build our own.
I've gotten some good advice from people, but I know this project is going to boil down to 3 things: the controller, batteries, and motor.
I've heard that Lead-Acid are easier and more affordable to work with, but the possibility of LiFeMgPO4 (or similar batteries) are tempting. Weight, physical dimensions, kwhr output will all be factors in the descision process.
As far as the controller goes I've been steered in the direction of the Alltrax 7245, although I'm seeing plenty of options from Alltrax; I'm just not sure where to start from.
Motors: I keep hearing about the Agni R95, although with a price of around $1400 this would eat up a lot of the total budget. I've seen other options like the Etek-r and the Perm PMG-132, I'm just not sure what the best bang for the buck would be.
One of the biggest issues I'm having right now is the battery situation; From what I've read so far, it seems like 72 volts is the sweet spot for operating voltage- that would mean 6 optima batteries.
Our team has a estimated budget of $3-4k USD. We have access to machine shops and are all mechanically inclined.
What are some good sources of info (other than this website) to help me educate myself in the finer aspects of a project such as this. In addition, since I will most likely have to buy most of components from the internet, where are some good places to order from. Thank you for your time,
UCFdave
1 - 14 of 14 Posts
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1,379 Posts
It's going to be tough to get the range of a Brammo with lead acid. It's going to be tough to get lithium with a $3k or $4k budget.
Can you lower your top speed or range requirements? That can lower the cost significantly.
Can you lower your top speed or range requirements? That can lower the cost significantly.
Joined
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1,629 Posts
Some advice:
1-Don't hesitate to go with lithium. When you search you can find good price. Lightweight, better range, more cycle, higher power (sometime).
2-Go higher in voltage. someting between 100-150 volt.
Exemple with lithium 3.3v. 40s (132v) and 40Ah is the same amount of energy and price than 22s (72v) and 73Ah. That give higher top speed and better effiency.
Recycled an use DC series forklift motor is often a good way to reduce by 1000$ your motor budget. You can also modificate it to reduce weight a bit.
You can see my motorcycle project bellow. That cost a bit over 4k$ without the bike price.
http://www.diyelectriccar.com/forums/showthread.php/suzuki-drz-sm-2005-electric-48239.html
1-Don't hesitate to go with lithium. When you search you can find good price. Lightweight, better range, more cycle, higher power (sometime).
2-Go higher in voltage. someting between 100-150 volt.
Exemple with lithium 3.3v. 40s (132v) and 40Ah is the same amount of energy and price than 22s (72v) and 73Ah. That give higher top speed and better effiency.
Recycled an use DC series forklift motor is often a good way to reduce by 1000$ your motor budget. You can also modificate it to reduce weight a bit.
You can see my motorcycle project bellow. That cost a bit over 4k$ without the bike price.
http://www.diyelectriccar.com/forums/showthread.php/suzuki-drz-sm-2005-electric-48239.html
Guys,
Thank you for the support so early on! This is something that was thrown at us pretty quickly and we've been scrambling to educate ourselves on the various aspects of the electric motorcycle. Keep in mind when I'm asking you questions, I'm behind the power-curve compared to you guys.
What I've seen so far:
A lot of the homebuilt bikes, usually built by garage enthusiasts use Lead-Acid batteries, seemingly for simplicity, availability and cost. What I've come to realize is that the Lithium batteries are somewhat more expensive, yet yield higher performance, increased battery life, and are smaller and lighter than Lead-Acid.
Yabert,
I looked over your build, I must say that I'd be very happy if our bike ended up as well as yours. I really liked how you made your own battery packs, so that you could shape them to fit in the space provided. I'm curious, what are the operational specs on your bike as far as range and top speed?
Additionally, through the short research I've been able to complete in the past few days, most of the Li batteries are manufactured in China, like Thundersky; I've been reading stories about batteries that people have ordered, and never recieved-we won't have the time or budget to deal with this. Are there some reliable on-line or physical retailers within the US where we can buy the batteries from? Also, how do you go about charging your batteries?
Yabert, you mention that we should run a higher voltage, again going off the little prior knowledge that I have and recommendations from friends, that would put us out of the range of the Agni, Perm, and Etek 72V max. I'm assuming based off your build that forklift motors are rated for higher voltages; What are some things or models that I should keep in mind when researching this alternative motor option?
Frodus,
I tried to log into to elmoto but it'd just kick me back to the main screen, is this due to the server crash, and not just me?
Again, thank you guys for helping me and my team along the way, the advice and knowledge base here is invaluable.
Thank you for the support so early on! This is something that was thrown at us pretty quickly and we've been scrambling to educate ourselves on the various aspects of the electric motorcycle. Keep in mind when I'm asking you questions, I'm behind the power-curve compared to you guys.
What I've seen so far:
A lot of the homebuilt bikes, usually built by garage enthusiasts use Lead-Acid batteries, seemingly for simplicity, availability and cost. What I've come to realize is that the Lithium batteries are somewhat more expensive, yet yield higher performance, increased battery life, and are smaller and lighter than Lead-Acid.
Yabert,
I looked over your build, I must say that I'd be very happy if our bike ended up as well as yours. I really liked how you made your own battery packs, so that you could shape them to fit in the space provided. I'm curious, what are the operational specs on your bike as far as range and top speed?
Additionally, through the short research I've been able to complete in the past few days, most of the Li batteries are manufactured in China, like Thundersky; I've been reading stories about batteries that people have ordered, and never recieved-we won't have the time or budget to deal with this. Are there some reliable on-line or physical retailers within the US where we can buy the batteries from? Also, how do you go about charging your batteries?
Yabert, you mention that we should run a higher voltage, again going off the little prior knowledge that I have and recommendations from friends, that would put us out of the range of the Agni, Perm, and Etek 72V max. I'm assuming based off your build that forklift motors are rated for higher voltages; What are some things or models that I should keep in mind when researching this alternative motor option?
Frodus,
I tried to log into to elmoto but it'd just kick me back to the main screen, is this due to the server crash, and not just me?
Again, thank you guys for helping me and my team along the way, the advice and knowledge base here is invaluable.
Joined
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119 Posts
my question is: Do you realy think that you can build a better bike than a BRAMMO for just 4k$? I dont think so.
Just the batteries in the Brammo bike are more than 4k$...as long as i know the have around 8-10kWh onboard, right?
Just to be realistic...
Just the batteries in the Brammo bike are more than 4k$...as long as i know the have around 8-10kWh onboard, right?
Just to be realistic...
Joined
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6,620 Posts
Hi Dave,
One of the things you have to decide
Are you building a Bike or a Motorbike?
If you are building motorized bike then you need to keep it light
A Motorbike has different dynamic and will weigh a lot more
Adding weight has a dynamic all of its own - heavier parts require other heavy parts
Making it light means that you need the courage to believe your calculations and stress tests - you are then targeting a 30-40kg machine - your money will go a lot further!
Making it motorbike - especially if starting with a frame designed for a much heavier and more powerful IC - will cost more and won't go as far
I think there is a market for something light enough to be picked up with small motor bike performance - electric mountain bike
One of the things you have to decide
Are you building a Bike or a Motorbike?
If you are building motorized bike then you need to keep it light
A Motorbike has different dynamic and will weigh a lot more
Adding weight has a dynamic all of its own - heavier parts require other heavy parts
Making it light means that you need the courage to believe your calculations and stress tests - you are then targeting a 30-40kg machine - your money will go a lot further!
Making it motorbike - especially if starting with a frame designed for a much heavier and more powerful IC - will cost more and won't go as far
I think there is a market for something light enough to be picked up with small motor bike performance - electric mountain bike
Right now the budget is TBD by the sponsor, we're estimating 3-4k based on what other groups are getting. In fact, they don't even have any performance specs that they desire, again, this is an estimate by our team.
RoughRider,
I'm trying to navigate through the Brammo site and it's not working for me, although I seem to remember the Enertia has a 3.1Kwhr battery. Keeping the bike light will be the keystone to the project.
RoughRider,
I'm trying to navigate through the Brammo site and it's not working for me, although I seem to remember the Enertia has a 3.1Kwhr battery. Keeping the bike light will be the keystone to the project.
Joined
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8,155 Posts
Might not fit your budget but this Enertrac hub motor makes for an easy install and gives you more room for batteries in a smaller bike:
http://www.enertrac.net/product.php
http://www.enertrac.net/product.php
I think its possable. My secca conversion was just under 3k. Of that $2000 was batteries. If I had to do it over again I would have I would have gone higher voltage. I'm only at 45 volts and my top speed is some what lacking. However, it accelerates like a bat out of hell and has great range. I haven't tested max range, but my longest ride so far was about 20 miles at 35 miles and hour.
I'm running:
12 100Ah Sky Energy
ETEK-R
Altrax Controller
I'm running:
12 100Ah Sky Energy
ETEK-R
Altrax Controller
That was one company, who is now out of business. I was one of the lucky ones who actually got my cells from them. There are plenty of reputable sellers out there. However, I'm not aware of anyone who stocks them. I think lithium depot was claiming on here that they were going to start stocking batteries September 1st.
Joined
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4,067 Posts
Manzanita Micro, Alliance Renewable Energy are both great retailers (I work for Manzanita and can help). There are many people that ordered from EVComponents that are locked in legal proceedings to get their batteries from the Owner. Consider what happened a rare occurance.
Higher voltage with only an agni isn't a great idea, but you can go higher voltage with a series wound motor like his. They can take about double the voltage. just be careful of arcing at higher RPM's, and realize you might have to advance the brushes.
Nope, sounds like its just you. Works fine for me and a couple people I just asked. Try using Internet Explorer. Click on Forums and try to post to introduce yourself.
Status Update..
Unfortunately, things didn't pan out so they've assigned us to a different project- a solar car cooler, not nearly is cool in my book. Once again, thank you guys for the support you showed me and my team early on,
-Dave
Unfortunately, things didn't pan out so they've assigned us to a different project- a solar car cooler, not nearly is cool in my book. Once again, thank you guys for the support you showed me and my team early on,
-Dave
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