# Yamaha E-RSX Motorcycle build (Thailand)



## Jaesin (Mar 6, 2011)

*Yamaha E-RXS Motorcycle build (Thailand)*

I'm in Bangkok at the moment but before I came here in June I rounded up some parts to do a motorbike build while I am here. It took me a while to find a donor bike but I settled on this 1981 Yamaha RXS 115 because it had all of the original paperwork. It can be difficult to find a classic with all the docs here but they are required as proof of ownership. 

The other great thing is bake was a nasty 2 stroke. 

The day after I got it I took it to a local shop and paid $14 USD to have it disassembled (My mother-in-law was thoroughly confused by this).

I have an admittedly small battery pack but I am just talking small trips for food, shopping and stuff like that. I am using some LiFePO4 Nano phosphate hobby batteries from hobby king. 
In total, I have 9 AH 99v pack. So that's 891 w/hours. They claim these cells can do 30c-40c, I'll find out if that is true. My controller (More on that in a moment) does 350A and 40C is 360 A. We'll see what happens.

The Motor I have is a Motenergy Brushless II PMAC ME0913. It's a Permanent Magnet AC motor. Says 30KW Peak. We'll see about that. I know there are others pushing this motor past it's limits.
http://www.thunderstruck-ev.com/motenergy-brushless-ii-pmac-me0913.html

The controller I have is the Sevcon Gen4 80V (Tops out at 116v): 420A for 10 Seconds, 350 for 2 minutes, and 140A Cont. At 99v, that's 41KW for 2 seconds, that's about 55 hp for a 130lb bike. Those are ideal numbers and I know I won't get that but it sounds like a good start. I got the correct contactor from Brian at Thunderstruck EV. He was really awesome about helping me get the motor and controller tested and ready for the trip.
http://www.sevcon.com/ac-controllers/gen4™.aspx
http://www.sevcon.com/media/2104/gen4_web.pdf
http://www.thunderstruck-ev.com/sevcon-g4845.html

I also brought a shunt, a JLD404 meter and some arduinos and lots of other tidbits for the build. The last bike is just another cafe racer that I like.


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## frodus (Apr 12, 2008)

Anything over 1C discharge (9A) and you will decrease the amount of energy you get out of the cells. At 10C, you might get 80% of the rated Watt-Hours.

I'd suggest a larger battery pack, maybe double (18Ah) if you can. Doing continuous 10C or higher on these cells isn't really realistic.

Good choice on motor/controller/chassis though. I'd just spend more time making sure you've got a solid battery.... as it's the bottleneck of this particular build.


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## Jaesin (Mar 6, 2011)

HI Travis. I'm sure you are right about that.

I've already used these batteries for a couple of years so I am not really that worried about abusing them a bit. http://www.hobbyking.com/hobbyking/store/__10311__Turnigy_4500mAh_6S2P_30C_LiFePo4_Pack.html

I only spend a month or so in Thailand each year so I don't want to spend too much money on the pack. I'll just use what I have here and see how it goes. I am hoping it performs pretty well. The whole bike should be super light. We'll weigh it when it's done. It would be nice to show it off a bit and hopefully get some local interest. There was an oil spill on one of the nicest islands here the other day so It would be great if some locals started to gain interested in other fuel sources.

Here are some screen shots of the motor adapter I mocked up in Autodesk Inventor. I'm trying to find a local place that can build it for me. I have a shop back in San Francisco where I go to do fab work but here, I don't even have a hammer so I'll be contracting out all of the fab work. It shouldn't cost too much though as labor here is pretty inexpensive.


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## frodus (Apr 12, 2008)

As long as you know the limitations. You'll probably only get 10 miles out of that pack, give or take a couple miles. I wouldn't expect you to get much better than 80wh/mi on that motorcycle, even with the lightweight design.

That's a nice looking motor mount, keep us posted on this build.... looks like it'll turn out awesome.

Also, when paralleling those packs, also parallel the balance wires if you can... or re-solder/weld the tabs so that each cell is in parallel with another.


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## Jaesin (Mar 6, 2011)

I'de be pretty happy with 10 miles. 
I'll probably drop the handlebars a bit to get a little better aerodynamics.

I made up some balance boards but they are not fused. I've used them like that for the last 6 months or so on my dorky little scooter.

Thanks for your comment on the Motor adapter. I hope I can find someone to make it like I designed it. I'm missing the TechShop right now.

I will also make some modifications to the frame. The way the frame is set up on most of these bikes is cheap to manufacture but wastes tons of space. I have a plan to hollow out the space inside the fuel tank including the main frame support. I want to mount my controller, DC-DC converter, contactor and relays inside the fuel tank. Hopefully I'll just have the battery pack, the motor and the heat exchanger visible on the outside.


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## Jaesin (Mar 6, 2011)

I designed a chill plate for the Sevcon Gen4 Size 4.

Building this design will require a couple of welds though.


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## Jaesin (Mar 6, 2011)

I've been having a bit of difficulty finding a CNC shop that can handle this small job at a decent price. It's mostly a communication issue.

If anyone knows of a shop that can handle these kind of small jobs in Bangkok or Samut Prakan, Thailand, let me know.

A couple more renderings in the meantime.


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## Jaesin (Mar 6, 2011)

Believe it or not, I'm still working on this project. 

I couldn't really find an engineer to help me (mostly due to communication issues) so I made the motor adapter and chill plate back at the Tech Shop in San Francisco.

Last time I was here (in 2015), I fitted the motor and everything lined up pretty well. 

I am back in Bangkok now and I still need to source batteries. I think Frodus was correct that that battery would be insufficient but it doesn't matter at this point because they were lost when someone stole my scooter.

Now I am planning on building a battery pack out of 18650 cells. I spec'd out a pack using LG 18650HG2 in a 26s25p configuration:

26s25p Pack 
650 Cells
93.6v, 75Ah
7.02 kW/h
5.6 kW/h usable energy.
32.5 kg for the pack

Good to 500A drain or 46.8 kW (62.76)

I didn't really find these cells for less than $3.40 each before tax and shipping from CN so I am looking at putting together a pack using cells from a couple of Tesla modules if I can find someone willing to ship them to me. I guess I could get away with using just one module but in 26s16p but I would have to limit the current to 320 amps or something like that.


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## dain254 (Oct 8, 2015)

I just built a very similarly set up dirt bike a couple months ago, I used 1/8" steel for my mounts since nearly any shop with a plasma table can cut them, and CHEAP! I had an ME0913 laying around that I started designing with but the debris intrusion was a major concern being a dirt bike... I ordered an ME1008 sealed brushed DC motor instead. I like how you have the motor constrained so it does not have an overhung load, I simply attached a hard rubber grommet under the motor so during a shock loading scenario all of the load was transferred to that. One thing I would suggest for power is a 2kwh Chevy Volt module if you can get ahold of one! The ME0913 will still run on 48V and give you plenty of power, especially on such a little bike!


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## Jaesin (Mar 6, 2011)

I think steel mounts are a good idea. I haven't seen a shop here with a plasma table but I would love to find one for some other metal work on the bike.

The problem I am having with acquiring batteries here in Thailand has to do with international shipping. There are allot of new regulations that apply to battery modules so I'm trying to figure that out.

- Jaesin




dain254 said:


> I just built a very similarly set up dirt bike a couple months ago, I used 1/8" steel for my mounts since nearly any shop with a plasma table can cut them, and CHEAP! I had an ME0913 laying around that I started designing with but the debris intrusion was a major concern being a dirt bike... I ordered an ME1008 sealed brushed DC motor instead. I like how you have the motor constrained so it does not have an overhung load, I simply attached a hard rubber grommet under the motor so during a shock loading scenario all of the load was transferred to that. One thing I would suggest for power is a 2kwh Chevy Volt module if you can get ahold of one! The ME0913 will still run on 48V and give you plenty of power, especially on such a little bike!


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