Laptop Powered E-Bike

rebelrider.mike

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May 25, 2017
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383
My phone isn't quite fancy enough to do videos. I'm using an old video camera and external mic. I managed to get one that does high def video, but I've always had trouble with audio. It comes through loud and clear on my computer when I edit. But as I said, my computer sound is so loud I have to turn it way down, so I think I have to edit it louder than I'm comfortable with in order for other folks to be able to hear.

As for the bearing, it looks pretty standard, so if it does wear out, I should be able to find a better one of the same size. For now I just want to see if the thing will work. Also, I kept the old springs, so if I have issues with the new ones, I can put the old ones back. I'm thinking of drilling some holes in the sides so I can see what's going on. My old electric drills all have sparky brushes and vent holes, so I think it will be ok.

I really think that lighter springs will go a long way to reducing friction heat though, so I want to try. Also, I'm thinking of putting a fan behind the motor to actively blow across the fins. I don't think I'll be going fast enough for regular air flow to make a difference, LOL. I may also try to put some kind of heat sink on the back of the motor. Still thinking that one through though.
 

rebelrider.mike

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May 25, 2017
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Last video on the motor, at least for a while. Finally got to use it at 24V, and I'm happy with the results.

Waiting on some parts so I can move on to the battery. The cells are ready to go, but I've got to make sure the shape I have will fit in the bike, and none of the soldering has been done. Still need to get a BMS, and a way to charge it, build a box for it... Lots of details.
 

rebelrider.mike

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May 25, 2017
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Trying something new.
I used a screen capture app on my computer to record video part 4: doing battery math. Folks already familiar with battery design may want to skip it.
I strongly recommend not watching this while driving or operating heavy machinery. Drowsiness is likely to occur, LOL. You wouldn't believe how many "uhs" "sos" and awkward pauses I edited out!

Anyway, here it is:
 

Sammm

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Jul 15, 2018
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This project seems like everything I've done plus much more that I was never brave enough (or rich enough) to preform! Best of luck with your battery, may your parallel cells stay balanced, and your pack stay cool!
 

rebelrider.mike

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Finally got my 3A fuses in the mail!
Still working on the next video, but in the meantime, I took a bunch of pictures.


image_esxsoc.jpg

Organising cells via repacker.


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Ready to solder!


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First two series are connected.


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The tape is there to make sure I don't solder the wrong cells.


image_aiaocu.jpg

The left side is done. Now it's time for the right side, which will have fuses. Here I've got 3 of the 8 series done.


image_ihngzc.jpg

Done! Still waiting on the BMS, and I just realised I don't have any 8s balance cables. I'll have to order some. Soon it will be time to build a protective box.

In other news, I have 2 fans, 2 heat sinks, and some thermal compound for the motor. I'm also putting together a cowl to move the air across the heat sinks more effectively. It looks like the freewheel I bought will be adaptable as well. I have an unrelated project I need to finish up this month, before I can work on that though.
 

Korishan

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Nice. Good idea with the tape ;)
 

rebelrider.mike

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May 25, 2017
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Here's part 6: An intro to the bike I'll be using, a ton of battery design, and a little about the actual real life battery I made.


The BMS board is finally in the US, so I hope to get it next week some time. I've also got connectors, threaded rod, shrink wrap, and nylon bits. I'm about ready to start building the box!

I've finally started to design and find specific parts for the electronics and battery charger. Since I'm using 4" PVC pipe fittings for the motor cowle, I think it would look cool to have a 3" PVC pipe to house the electronics if I can fit them. A 90mm PC fan should fit perfect on the end of a fitting. I'll have to go back to the Habitat store and see what they've got.

I'm also doing a sort of cost analysis for this project. I usually don't because knowing how much a project costs sucks the fun out of it for me. But in this case, since the idea is to build an ebike cheaper than from a kit, I've decided to go ahead and do it.

Two things I haven't found yet though: I'm looking for a battery (or set I could put in parallel) that has 1kWh, 70A, 30V, 33Ah. I'm pretty sure no such battery exists for ebikes, but I'm looking for something in the ballpark that I can compare my battery to. I'm also looking for a charger for such a battery. Something like 600W. Now remember, I don't want to actually buy these things, I just want to see what they would cost if they could be found, so I can compare to what I'm building.

I'll make a video on that toward the end of the project, but for now, the next video will be yet another motor mod video. Hopefully by the end I'll have it mounted to the bike!
 

rebelrider.mike

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May 25, 2017
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Who's got two thumbs, and finally got his BMS from China?

This person! -> :D <-


Progress has been slow, so I've been looking at other stuff I haven't paid much attention to yet. I've been asked a couple times about gear ratios and torque. That sort of thing. Problem is, I don't know much about that stuff, and what I've seen on the internet is rather confusing. I can though, leave you all with some measurements, and those that are interested can maybe enlighten me on how it all works.

I measured my 26" wheel, and found out that the wheel with the tire on it is actually 26" in Diameter.
The sprocket fixed to the wheel is 7" in Diameter, 44 teeth.
The freewheel cartridge attached to the motor is 2.5" in Diameter, 14 teeth.

I figure an average speed of 10 mph would be nice. Maybe a little slower going up hills. The idea is that I will be pedaling as much as I can, and the motor will be the assist, rather than the other way around. (This is for me to get a little more fresh air and exercise after all. :) )

I searched for quite a while, but could only find vague remarks about how much torque a car starter motor typically has. I found 1 reference that suggested a typical starter motor might be around 24 Nm. Another site,what-when-how.com, said a 4-cylinder engine needs 8 Nm / L. Which for a 3L engine as my motor is designed for, would work out to 24 Nm. Converted to ft-lbs, that would be 17.7. Kind of nice that the two websites agree, but I sure would have liked to find a torque vs RPM chart.

As for how much power is needed to get me up a hill, well, I don't know how to translate torque into whatever that would be. Horsepower? After a while I just gave up and searched for ebike calculators:
http://www.kreuzotter.de/english/espeed.htmThis one calculates man-power in Watts, but is not actually for ebikes.
https://electricscooterparts.com/motorwheelgearratio.html This one is more for wheel ratios and RPM
I also just downloaded an "Inclinometer" app for my cell phone. Hopefully I'll be able to use it to find out the grade of all these hills I keep complaining about, LOL.

So far, I've learned that a 26" diameter wheel will go about 129 RPM at 10 mph. Seems I have a 3.14:1 ratio, so the motor will be going about 406 RPM. That other website also told me that a typical engine spins at 100 RPM by a typical starter motor, and has a 10:1 ratio. That means the starter would be spinning at 1000 RPM.

I've also heard that permanent magnet, brushed motors have more torque as the go slower. So hopefully I'll have more that 17.7 ft-lbs at my 406 RPM. Will that get me up the hill? Still don't know...
 

rebelrider.mike

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May 25, 2017
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Got the BMS wired in. No idea if it's working, LOL. I need to get going on the box and connectors for the battery so I can try it out!

In the meantime, I've updated and reorganised the wiring diagram:
[img=800x600]https://i.pinimg.com/originals/b5/6b/27/b56b27c4c269d56fa4d4038f8f615f33.jpg[/img]

I also figured out some of the gadgets that will be on the handlebar, and what Voltage, if any, they will need. The potentiometer that controls the PWM doesn't need power.The relay switch, Temperature meter, and Amp meter all will run on a wide range of Voltage, but all will work with 12V. I need a buck converter for the fans anyway, so that works out. I just need to count up the Amps and get a converter that will handle the current.

I just put a headlight together that runs on 4-4.5V. I think I'll just make a seperate battery for it, since I don't even know if I'll keep it on the bike or not.

I also got one of those fancy battery meters. The kind that tells you the overall Voltage, and the Volts of each series. That one connects directly to the battery.

The temperature meter is a new thing. I was shopping for electronics and discovered that there is such a thing as a dual display temperature meter. Two probes go wherever you want to monitor, and each temp is displayed on the gauge at the same time. And it's in Fahrenheit so I'll know what it means! I plan to put one probe on the motor, and the other up my... battery. (Just seeing if you're paying attention, LOL)

As for the charger. That's a whole other story. But I have a plan. :D
 

rebelrider.mike

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May 25, 2017
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Yay, more video:

Seems the motor and battery are the vast majority of the work on this bike. I'm back on the motor, fitting a freewheel cartridge and a roller bearing. Also a couple miscellaneous things. I've actually got a lot more footage to go through. I intended to make a final motor video ending with it on the bike and running, but that would have been way too long. But I'll give you a spoiler: The motor is on the bike and it (mostly) works! :)
 

rebelrider.mike

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Finally got all the wires soldered and hot-glued onto the battery!
Not nearly done with soldering yet, but now I can put this guy in a protective box.

Now that I have a balance cable, I can check how the BMS is doing at balancing the series. Seems to be doing nothing, unfortunately. Oh well...
Anyway, I'll get some photos up when I get the battery in a photogenic place. Very excited to have this milestone complete! :)
 

rebelrider.mike

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The headlight is on the bike now. I painted the battery holder black. Not pictured is the bracket I made to hold it still.

image_nlxhso.jpg
 

Oz18650

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Oct 2, 2017
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rebelrider.mike said:
The headlight is on the bike now. I painted the battery holder black. Not pictured is the bracket I made to hold it still.

image_nlxhso.jpg

Has there been any more progress with your project?
 

rebelrider.mike

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May 25, 2017
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Thanks for asking!

I have a couple videos yet to edit, and I've done some calculations as far as the power consumption of the cooling fans and gauges, but for the most part, the ebike project is on hold because I had a free motorcycle dropped in my lap. It's free because everything on it is broken, and I've been refurbishing it. Eventually, once it's road-worthy, my son is going to ride it until he can afford his own bike.

Oh, I also have the big left and right covers made for the battery. And all the wires have been secured so they're not all flopping around. It looks like fall weather is approaching my area, so I may be switching back to the ebike for a while. :)
 

rebelrider.mike

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May 25, 2017
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When the battery is at it's lowest Voltage will be when it needs to deliver the most Amps in order to maintain the Watts. So 400W / 42V = 9.5A. Yep, my math agrees with your's. If you are using old laptop cells, I'd recommend 0.5A maximum for each cell, so I'd recommend 19 cells in parallel. You could get away with fewer, depending on how much you trust the cells at higher current.

Also, you might have posted in the wrong thread? This thread is for building an eBike. :)
 

Korishan

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rebelrider.mike said:
Also, you might have posted in the wrong thread? This thread is for building an eBike. :)

Nope, rozalisa has confirmed to be a bot. Spammer removal initiated. I was just waiting for the second post to make sure. ;)

The bots are getting more sophisticated as they must be implementing AI. We've had quite a few the past few weeks.
 

rebelrider.mike

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May 25, 2017
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Refurbishing my motorcycle has slowed down a bit because of winter weather. I may work on the eBike again.

I made this video a while back, but forgot to publish it. It's basicallyalecture on how I'm keeping my battery safe. For all you folks who already know about safety features, this will probably be really boring. But for anyone considering building a battery and you're interested in making it relatively safe, I hope the information is helpful.

Not every battery would need these features, and some batteries may benefit from features I've not included here.
 
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