My first DIY electric motorcycle

Joined
Nov 27, 2020
Messages
62
I begin this build thread with a warning. This will be a very slow process with lots of time in between updates.

I've full on decided to take the plunge and convert an old noisy gas bike to a futuristic electric motorcycle.
This log will feature all the parts I'll be purchasing as i purchase them and hopefully a cost associated with it. So if anyone wants to emulate what I'm doing in the future (probably not recommended, haha) then you can know what you're getting into.

Purchase group #1

Batteries
probably the most important part of any bike build and here's what I decided to use. (Edit: batteries changed in later post)
32s LiFePO4 at 90ah capable of discharging at 2c (180A)
Cost of this item is yet unknown as I'll probably get hit with customs charges when they come into the country. I'll update when I have a figure

Wire
A much more straight forward decision, but don't skimp on this as you'll be paranoid whenever you hit the throttle and give it all its got. It's best to oversize and I've done that, but not by a large margin as I'm still on a budget
I've selected 10 feet of 2AWG pure copper welding cable from princess auto (canadian harbor freight) for a total of 45 dollars. Probably a little more than I need, but this way I won't have to buy more if i make a mistake. Welding cable is heavily insulated so I'll have plenty of temperature tolerance if i want to run the full 180a through it for any reasonable amount of time.

Connectors
so far I'm up to about 20 dollars. But I have a lot of spare parts from the RC world in the garage (XT60/90 connectors) so I'll likely not have to go too overboard with this category unless something goes very wrong.

Heat shrink (Edit: ordered 420mm for new battery size)
For the battery, not for wire. Another ali express find (most of this bike will be). picked up some 550mm diameter heat shrink so once the battery is built then I can keep it all nice and contained in a sleeve to reduce the likleyhood of chaffing on the inside of the battery box. About 60 dollars after shipping.

Display
CT22 from QS. roughly 80 dollars shipped to my door. I wish it had a watt meter integrated into the display, but It's a feature i can live without. Just would have been nice.

Keen eyed readers may have noticed there's no bike listed yet. Thats for a good reason too. I'm having a hard time sourcing one for less than 1500 and I really don't want to ruin a perfectly good running bike for this project. So I'll take my time looking and hopefully get something that doesn't run for nice and cheap.

Wish me luck and I welcome any input.
 
Have you checked out any junk yards for a bike?

:D :bolt:
 
I'll be honest, that didn't even cross my mind. I'm only in a small town so there's nothing immediately nearby. I'll give some yards a call first before I stop by with a borrowed truck and see what they have.
I'm guessing someone somewhere has blown an engine in a bike that's just out of warranty. Lets hope at least
 
Are you sure you want to be at 32s? Give some thought to weight. I did a quick web search and I believe one 90ah Lifepo4 is 1.9kg, putting your total weight of batteries at 60kg. Your max voltage will be 115 volts, and finding a motor controller, while possible may be rather challenging.

Another suggestion for developing your design would be to start with looking at motors first -- obviously there are a lot of motorcycle motors out there but you that will drive a lot of your decision making for the rest of the bike. Also note: big motors aint cheap.
 
Yup, I'm sure. My primary reasons for going 96v are to get more torque and to keep my amperage low. And of course, the higher the voltage, the lower the current per watt. Also the lower the current draw, the more capacity I can squeeze out of the battery pack (not much more, but I bought some B grade cells, so I'll take any extra amp hours I can get it).

Controller and motor are not an issue.
Controller will be a Kelly KLS96401 - Capable of up to 120v and continuous 160A. That gives me roughly 16-18Kw (depending on voltage sag) of sustained power with my battery configuration. More than enough to hit my 120kph max speed target.
As for motor, I'll be going for either an 8kw or 12kw hub motor from QS. Will mostly depend on budget at the time of purchase as they can both be purchased in either 3.5" or 6" width configurations. Both are rated up to 120v so they will have no problem with my 116.8v peak voltage.
I was also able to source a 120v to 12v DC-DC converter

The only parts that were a little harder to find were a BMS capable of handling 200A at 32s and a charger. But I have both of those sourced now so all I'm waiting on is a bike frame and budget.
 
owhite said:
provided the kelly KLS96401 really can go up to 120V that sounds reasonable. I run a QS205 on 24s lipo and I can get 88kph. Any faster than that I stop looking at the speedometer. :)

Well according to the kelly web site, its rated for 120, so im happy with that. Also I've seen youtube videos of it holding up to a 32s LiFe battery so thats proof enough for me.

As for not looking at the speedo, I'm going to need to do that. I want to get 120kph as I want to take it on rural routes and the highway, so I will need to know how fast I'm going to avoid ending up with a ticket. The limits where I'm moving are 80k on the back roads and 100k on the highway. I'll be using the CT-22 dash as I have it on my other bike so I'm at least a little familiar with it.

Also, I'm still waiting on my batteries to show up from ali express. Shipping is painfully slow on these things. Apparently they haven't even left china, and its been over a month already.
 
Bike acquired!

Out of the blue, and rather happily, I found a guy at work selling a CBR 125 and seeing as how he knew who I was, he was more than willing to entertain my crazy rantings when I asked him to measure some unusually specific parts of the bike.

Turns out that based on the measurements, the battery I have ordered should have around 10mm of clearance between the frame rails. Hopefully that ends up working and I can actually put in all the batteries I ordered. I really don't want to have to downgrade this thing to 72v when I have 96v of batteries.
As for the motor. I'll likely have to make up a couple small spacers, but overall, it should be a fairly simple install. The rear swing arm is only about 20mm too wide based on initial measurements. Maybe QS can do some little modifications to the motor if I'm lucky.

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So there's my new bike. A 2008 Honda CBR 125, soon to be a CBR 8KW-E
The good:
The body is in wonderful shape with no rust to speak of
It has only 2000 km on the engine/body
All the panels are scratch free
Compared to my proton the suspension is cadillac levels of soft so it's going to be so much more comfortable

The bad:
It's in immaculate shape and runs wonderfully, so it's kind of a shame that I'll be gutting the bike
I've never seen a conversion of a CBR to electric so I'm in unknown waters here.

Anyway, the first step of the project is under way. Wish me luck.
 
Nice looking Honda. I'd be tempted to sell it or keep it as in and use a different bike; just because it is in such good condition.
 
The thoughts crossed my mind as well, and I did get a very good deal on it (1000 cad or 800 usd) so getting more than I paid wouldn't be much of a challenge. The only problem is that I got it from a buddy I work with, so re-selling the bike just seems a little shady to me.
I'm not in a rush to pull it apart quite yet though, so maybe if I still have it all in one piece after I move then I'll consider trying to turn a profit on it.
It's only got 2300 km (1430 miles) on it so it's practically brand new. So for a bike this age to have only that is incredibly rare. I've seen plenty of this same bike in worse shape and higher mileage go for more.
 
Update!

I know, so much rapid progress in a short period. How do I do it?

Anyway, I finally, finally, finally, settled on a battery design. I feel like I've said that before, at least three or four times now. But this time I've bought some cells, so I'm fixed as for what I'm going with so I guess I can't change it any further.

Edit: forgot to mention that my old LiFePo4 cells that I ordered turned out to be a scam seller. Ali express fully refunded me so no loss on my end, just a little wasted time.

I've chosen an 18650 Panasonic cell rated at 3250mah and capable of discharging continuously at 2C. Which for my application is pretty well just right. I'll have a 28s20p pack giving me a total capacity of 103.6 V nominal at 65Ah (6.7 Kw). That gives me a constant output of roughly 13kw which isn't too far from my 8 Kw motors peak output of 16kw. Easily enough to propel me to highway speeds for a short period of time. As for longevity, the cells are rated for 90% capacity after 300 cycles. So if i can get my desired range of 100km per charge, than that leaves me with a 90% capacity battery after 30,000km. Perfectly acceptable in my books. I really wanted to go with a LiFeP04 chemistry for basically an almost indefinite service life, but with the size of this frame I just can't get it working with the capacity I needed.

Edit: Here is the ad for the Ali express cell and the discharge data sheet to go with it.
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I've also managed to secure myself a spot welder (SQ-SW2), nickle strips (0.15mm, ladder style), and two battery chargers (Lii-500s), so I can give every single of my 560 cells a full test before I weld them into a pack. Yeah, it's going to take forever. Hence the two chargers.
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In other news I also found a new bike. Well, same bike actually, and in a different province, but its got no engine! So hopefully, if it's not sold in the spring when I may be moving, then I'll attempt to sell my bike and replace it with this "broken in just the right way" bike.
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I've never worked on a bike, and I've never built a battery, so this is going to be a hell of a project. Once my parts come in.
 
That is a lot of cells and as you know will take a long time to cycle on two of those chargers. I ended up doing the same thing (same chargers too) for my first battery build and it took a long time. For my second build I went a different route for testing the cells that seemed to work very well (pack staying in near perfect balance) and was a much quicker process.

Instead of discharging and charging each cell to get a measured capacity; I purchased an internal resistance (4 wire) measurement tool ($50 CAD on Aliexpress) and simply measured the resting/shipped voltage and internal resistance of each cell. New cells of the same model are usually shipped at the exact same voltage; so that is an easy way to check for any outliers. I then matched up the internal resistance for each cell group so that all groups would be as close as possible. Just be sure that the cells are at the same temperature (and state of charge) when measuring IR. Almost a year later and the pack stays very well balanced.

Some might argue that you should do both capacity check and internal resistance check but I found that just doing an IR check on brand new cells is sufficient while also noting any major deviation in resting voltage. Any testing is better than none; but just thought I'd share my experience.
 
Thanks for the input. I may have to have a look into that.

I have done some quick napkin math and found that it's going to take a great many days to check all these cells. It comes out to 70 batches of cell tests. However I don't have a lot of time to weld up cells each night so I'm really not too worried about the time frame. Also bike season doesn't start in Newfoundland until at least June so no rush in that sense.

My plan was to have each 1s20p line of cells matched for capacity so I'll record each cell capacity and math them up to have nicely matched parallel lines.

I'm currently looking to solve the problem of a "collector" on the first and last of my parallel connections. Initial searches are coming up with a lot of conflicting information, so I don't really know what to do.
I want to be able to pull 120A continuous and it seems that either a soldered 8awg or 6awg wire on top of my nickel strip will meet my needs, but I've seen data sheets show that I need anything from 10awg or 2awg. I only need about 6 inches of wire coming off the battery then I plan on swapping to some 4awg welding cable for the longer power runs to the controller.
I'm guessing that as the run is very short then a smaller gauge wire is tolerable but I don't want to be worrying about my battery melting its wiring.
 
I've officially ordered the rest of the cells.

I now have 580 cells to test and I'll ditch the 20 lowest capacity ones as spares for another project bringing me to a 28s 20p pack. I''ll let you all know how it goes once I'm done testing them in five years.

Basically I'm a little broke at the moment so needless to say a 2000 dollar battery isn't the first thing I want to buy so bitcoin to the rescue. I bought the first 140 cells with my own money and the rest with bitcoin via paypal. So now once I get my battery built I'll order my motor/controller and other accessories.

As of this moment I've got a cost breakdown ready. To no ones surprise I'm sure, the largest cost so far is the battery followed by the bike. (edit: prices are all Canadian dollars)
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Hopefully the shipping won't be crazy long because I can't wait to get started on this.
I'm going to continue to log as many of the parts and costs as I can just in case anyone wants to emulate this project in the future. I'm really trying to be careful to not spend money on unnecessary parts and pieces and drive the cost of this project up. I really like the idea of electric motorcycles and think that so many of the ready made ones out there are either FAR too expensive or suffer from a depressing range/speed.
If I can get something under 5k with minimal modification that will go 100kph and travel 100km then I will be very happy.
 
SlowCo said:
I love your choice of donor bike. Will follow your progress with interest!

Thanks, but so far from my experience I would not recommend this bike. The frame shape really doesn't lend itself to electrification very well. The primary reason is that it narrows up to come to a point to join up with the forks surprisingly far back on the frame. This doesn't allow for a very easy battery install. If it didn't do this as drastically then I'm sure I could have easily fit the 9.5kw in this frame that I wanted originally. Maybe by the time I'm done building this thing a real CBR-E will exist for me to compare to. We all know the general public would love a 125cc equivalent e-moto.

But, who knows, maybe this will end up working out really well and meet my needs with only 6.7kw. If my skinny tires and aerodynamic shape can help me hit 100kph and get 115 watts per mile, then I'll be happy as a clam.
 
But you have so much space under the frame to put a battery pack. Maybe you'll need to widen the fairing a bit to fit a large pack.
 
SlowCo said:
But you have so much space under the frame to put a battery pack. Maybe you'll need to widen the fairing a bit to fit a large pack.

There's space for sure, but it's not all usable. There are a lot of horizontal braces in the frame that make lining everything up somewhat impractical. I'm already going to have to remove some of the old engine mounting brackets to fit the currently planned battery in place making this a permanent conversion. No going back if I ever plan on selling the bike and salvaging its parts for something else.
The 560 cell battery is only about 380mm length x 225mm in height x 140mm width. Which is surprisingly small for being almost 7kw. The only way I can fit any more capacity in it is to change the cell configuration and make it a bit taller but shorter. That will let me reach 8kw but then I may not have a lot of room for the controller so I'd rather be safe side when it comes to space for my first build.

I'm not actually worried about width under the body panels as to get in between the frame rails It needs to be narrow anyway so that just kind of worked out.

I've done a mock up of three batteries to see what I can fit and where so here's the current rough battery location with a fairly accurate size "battery". If I make it any longer then the front suspension may start to interfere with the battery location.

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Some battery weight could go over the frame to provide some counter balance when coming out of a fast turn. It would also give you more space for a larger battery. Maybe figure the weight of the engine you are pulling vs the weight of a full tank of gas and figure the percentages of weights you can fill with battery weight top and bottom.

:D :bolt:
 
As should be rather obvious from my previous picture, the bike is still completely assembled and in a functional state. As I still have a month or two before my batteries come in from the shipper then I have at least until then to make a decision if I want to order an extra row or two of cells to see if I have the space.

I've basically abandoned the idea of having two packs in parallel as then I have to buy two bms so I'd ideally like to fit the largest single pack I can.

Once I get the bike apart then I can really see what kind of space I have to work with rather than just my mock up packs from outside the bike. With the potential of getting a semi scrapped bike I don't quite want to go chopping this one up to make room for everything quite yet.

As for weight, my battery should come out to roughly 30kg and I'm guessing the engine plus 10kg of fuel will likely work out to be pretty comparable. So if I can fit it vertically in the frame then the weight distribution should be pretty close to spot on. I'll be sure to take lots of pictures when I finally chop up either this bike or that white one I showed earlier. I'd really like to save a few hundred dollars by selling this one if i can.
 
Got my new wire crimper in the mail the other day, and what better time to give it a test than in a power outage.
Fabricated myself a new set of 6awg welding cable leads to connect my 1500w inverter to a classic car battery. Enough for when the power goes out and you need to run a few things.
When my cells finally come in and I need to wire up the battery and controller this is going to work out pretty well I think.

The crimper is only a relatively inexpensive amazon brand hydraulic one, but I'm happy with its performance and would easily recommend it for anyone looking to occasionally crimp some larger wire. For my non commercial/industrial applications in battery building and solar power it's perfect. The cutters worked really well too. 6 AWG wasn't exactly like cutting butter, but it was far easier than I expected and easily handled with one hand.

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Millhouse_5 said:
The crimper is only a relatively inexpensive amazon brand hydraulic one
Which one? (link, if possible)
 
since the link is 10 lines long I won't share it, but just search "AMZCNC hydraulic crimper" and it will show right up. It's literally an amazon basics tool, but it's fine for my uses.

On to other news.
I got BATTERIES!!!!

My first batch of 140 Panasonic NCR18650B cells arrived in the mail after almost two months of shipping time.
Threw them inside and waited for them to come up to room temperature and then put them on the charger. The first batch is testing now and It's looking good so far. The first 20 cells have all been within 0.05v of each other and are charging nicely to 4.2v.

I have many more cycles to go to get all these things tested and marked off but the effort is going to be worth it to make a nicely balanced pack for the bike.

Packaging was functional but somewhat lack luster, but at this price any scuffed cells i find will just be delegated to the lawn mower.
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PS: Shipping to Newfoundland, Canada from Aliexpress was just under 8 weeks for anyone looking to order some of these very inexpensive batteries.
 
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