Building a 72V ebike

[sahbin]

Hi, i am from Belgium and I followed this forum for a while and I finally decided to build my own e bike but I need your help. I am not planning on doing long trips but I need it to go as fast as possible ( Purpose : giving physiotherapy treatment at home and avoiding traffic, parking which is a disaster here in Brussels )
Here is what I want to use as components :
- HS3540 motor
- 60 INR18650-25R batteries 20S3P wired together with fuses (like Tesla) https://youtu.be/raBWFsPlx7w?t=424
- A Lyen controller but I really don't know which one to choose (9fet 72v sufficient ?)
- Cycle Analyst v3
- Turnigy accucell 6 ( how many do I need ?)
- PAS (Pedal Assist System), Cruise control module (would be nice), Throttle, Tork arm

- BMS --- this is where it gets confusing, I don't know if I need one and if yes which one to buy ??

Edit :
Desired max speed is around 40 to 50km and range 15 to 20km
26" wheel with disc brakes
mostly hills 10% grade
My weight 75kg$
Budget 1000 euros

 

[bowlofsalad]

- A Lyen controller but I really don't know which one to choose (9fet 72v sufficient ?)
- Cycle Analyst v3
- PAS (Pedal Assist System), Cruise control module (would be nice), Throttle,

- BMS --- this is where it gets confusing, I don't know if I need one and if yes which one to buy ??

Nothing necessarily wrong with the options you are choosing, but I recommend going with an adaptto mini-e or max-e instead. Lyen is trapazoidal, adaptto is field oriented control(FOC), FOC translates to higher efficiency motor operation and less noisy motor operation. Adaptto includes a display, you can get PAS, use cruise control, you can use a throttle. I'd probably use a battery monitoring system if I were you, the adaptto has an excellent one, you can check individual cell voltage on the display, monitor everything this way, it balances cells nicely. You can use a 28s battery or 100v HVC, whichever comes first. Check adaptto.com

- Turnigy accucell 6 ( how many do I need ?)

If you go with an adaptto, their BMS and a charging coil you can use lots of other kinds of power supplies for charging your pack. https://www.endless-sphere.com/forums/viewtopic.php?f=2&t=67579 Here is a thread with a bit of information on some really fantastic options. Incredible value compared to other options.

Tork arm

Doctorbass torque arms. https://www.endless-sphere.com/forums/viewtopic.php?f=31&t=29129 There are pros and cons to every retrofit option, but open mouth torque arms are the way to go in my opinion for electric bicycle torque arms.

I am not planning on doing long trips but I need it to go as fast as possible

How fast is as fast as possible? You can go pretty fast on an electric motorcycle.

 

[wesnewell]

Edit your post with this info.
http://endless-sphere.com/forums/viewtopic.php?f=3&t=66302

 

[sahbin]

Unfortunately the adaptto controller is out of my budget for now is there cheaper alternatives ?
And but how much amps could the battery pack deliver considering one battery can deliver continuously up to 20A (Sorry for the noob question)

 

[pixelzpusher]

Here's my advice on the batteries. You don't need 72v to go 50kph (30mph) top speed. You only need about 60v. I have 3 e-bikes and all go about the same speed depending how much voltage I wire up. On my 1000w hub motor, it is capable of 28-32 mph on 48v-57v. I ride 15 miles round trip to and from work each day and the motor and speed controller does not get hot at all at full throttle.

Many people use lipos because it delivers the amps you want and they're light. However, if you want longevity, go for lifepo4s. They are more than capapble of They will save you lots of money in the long run. I just picked up 4x of the following lifepo4s for testing and so far, they are fantastic!!!

http://www.batteryspace.com/lifepo4-prismatic-module-3-2v-20-ah-10c-rate-64-wh-6-0---un38-3-passed-dgr.aspx

Not sure you need 20amp capacity, but if you want the range, go for it. One charge will give me 30 mile range at full throttle going 30 mph.

On a side note, contrary to what others may say, a bms does nothing in terms of keeping your batteries last longer. At best, it just tells you which battery is going bad and to be on the lookout for it. Once a cell starts to go bad, it won't get better. A bms or cell reader tells you which one it is and to replace it. It won't nurse it back to health, no matter how much you balance charge it.

As for battery packs, I wouldn't get one big pack. I would buy 3s or 4s packs and wire them together yourself. It's easier to troubleshoot if one pack goes bad. Trying to figure out which cell is bad on a single 60v pack is a huge headache.

Good luck on your build.

 

[mrzed]

Do the laws in Belgium allow you to run those speeds? I'm pretty much a libertarian but if my employment depended on running an illegal vehicle through a major metropolitan area I'd think twice.

This from someone who regularly commuted on a technically illegal vehicle. You can more easily get away with it by staying near legal limits when anyone's looking and/or having a bike that looks like a bike.

 

[pixelzpusher]

You are so right about that. I ride my 30mph e-bike in the bike lanes with no problems everyday. However, I also recently started riding my legal 20mph e-moped in the bike lanes and got yelled at. Even though I am legally afforded the bike lane in California according to the California Vehicle Code(CVC), people yelled at me, and it's slower than my e-bike. I didn't really care as I carry the CVC paperwork with me just in case there are any problems both in my e-bike and my e-moped. To be inconspicuous, I would stay around 30mph on an ebike.