KTM65 Electric Conversion

[snydes]

Luckily for us Mark likes dirt bikes!

 

[VINSANITY]

Mark, I am very interested in the motor you purchased - can you send a link to where you got it from - thank you

 

[Mark911]

Mark, why did you choose to go with Panasonic cells and not Sony for this application?

I got both types in stock but we wanted to keep the cost as low as possible to start with. If the panos proved adequate then decision made. If not we’d need to consider another cell (like the Sony).

 

[Mark911]

Te

Mark, I am very interested in the motor you purchased - can you send a link to where you got it from - thank you[/QUOTE
98% of the decent small/higher performance motors are made in China. Everything else is either too industrial or exorbitantly expensive. Of these motors we felt the QS138 from QS electric was the best choice. If you do internet searches on the subject you’ll find this motor isn’t a secret.

 

[Bought-2-L8]

Nothing involving dirt bikes is big bucks, it’s a matter of limiting your losses.

I'm located in Anaheim and I look forward to buying a 2016+ 65sx for you guy to convert! I've been talking with Electrobraap on Instagram

 

[ElectroBraap]

Mark, I am very interested in the motor you purchased - can you send a link to where you got it from - thank you

It is a qs138 70h . Nothing fancy, but it’s well known for being a great little motor. Rated power is mostly meaningless on these Chy-Na motors it would seem.

-Electro

 

[ElectroBraap]

I'm located in Anaheim and I look forward to buying a 2016+ 65sx for you guy to convert! I've been talking with Electrobraap on Instagram

 

[TCMB371]

How much does a conversion cost if i have a rolling chassis?

 

[Mikec265]

Saw the new video, potential customer here in about a year. Any idea on price points yet?

 

[DonCox]

50lbs!? I wish haha! We came in about 10lbs more than the oem spec for a 65 as @Mark911 mentioned. With the current battery design, mass reduction is not possible unfortunately (not significantly anyways).

The 65 is about the size of a 110 so I think it will make a great pitbike. We have yet to see how a kid will be able to throw it around on a track. Hopefully we can test that sooner than later!

Electro

What is your battery setup. I am new to this forum, but have been building electric moto bikes for over 10 years. I am building a 50hp YZ25F 2008 now with a Alta battery copy. Sony VTC6 72V 21AH 210amps peak. I will have 3 pack . Each pack weighs 18lbs total 72V 63AH 630amps. 54lbs total. If you don't need the current there are better batteries that could make it lighter. What size and weight is you battery, and peak current?

 

[Mark911]

Essentially a 20 or 21s18p pack, correct? That's very close to what I'm building now for my full sized conversion. However, I'm not expecting 630 amps from 18p of VTC6s. Not without massive voltage drop anyway. The key will be the cell interconnections (to reduce resistance) and thermal management. The cell layout is very important as it dictates busbar geometry and therefore dynamic resistance. Choosing the optimum busbar material, thickness, and welding process is just as important. Thermally, I'm using the same passive design concept that Alta used but with thermal conduction at both ends of the cell, not just the negative end. Hopefully, my thermal model will prove correct and keep the cells under control for a full 15-20 minutes at Pro level. Even with passive cooling, the weight suffers when thermal is considered. Your weight per module suggests very little if any thermal control, passive or active. If that's incorrect, I'd love to know how you are getting the heat out.

Although I'm not personally involved yet, we're doing testing with Lipo based chemistry/construction as well and it's looking very promising. A minor weight hit but easier packaging and better C rating (which also means better thermal performance). Still need to access range, durability and lifespan.

Good luck with your projects. I'd be interested in seeing some of your work.

 

[DonCox]

Thanks for the reply and great info. I am running 20s7p for 140 cells per pack. I tried many different methods of spot welding for my bus bars, but could not get the size and material I wanted to work with spot weld. I wanted copper for the conductivity and lower heat build up, but in thickness, it doesn't spot weld.
So after a lot of YouTube research on power wall builder, I went with solid copper buss bar and smaller ones(fusable links) to the individual cells. After watching Shea Nyquist's video on the teardown of the Alta battery and talking to him via email, I found that the fusable links in the Alta are .5mm or .020" Aluminum. He felt quite good that this will carry 30Amps. I wanted something a little more robust, so I went with 1mm copper solid wire (#4 Stranded house wiring) for my fusable links, and the buss bars of 2mm. These are very easy to procure using Romex. #12 Romex is 2mm . I have a 250SX KTM that is electric and has been around all the so cal tracks, up til 2016. I moved to Lake Havasu AZ then. Anyway, it draws 400Amp, and I uses #12 romex for my Fuse in that bike. I have blown it once, with a short to the frame (a drill bit piece dislodged off a jump at Cahuilla,.)
I will include a picture of my cell pack partially done. I hadn't finished the + and- buses yet. Some of the unusual locations, I used thicker buss bars, #10 Romex. 2.5mm.
As a caution, and I'm sure you know this, these cells are very dangerous. A friend in Florida, building an almost identical Yamaha with a Me1115 motor, almost burnt his shop down building cells. Water bath or foam Fire extinguiher must be used. Dry powder does not work. My motor is a ME1304.
Anyway, I'm a little long winded here. But that is how I am going to try to keep my cells cool (wind). The cell holders I have, have a 1mm-2mm space in between cells I am going to force air thru the space with a fan system and directing air off the old radiator shrouds. I'll include a pic of one cell pack in the bike. These packs will be removable. You can see the Anderson connectors above the cell. the XT90 connector is for charging. There will be another outer shell on the Cell packs, similar to my KTM ( picture included.)

 

[DonCox]

Mark911,
I have used Lipo cells on my KTM for about 8 year., Two different packs, first was Calb 40AH prismatics 10C for 48V 400A, now I have Headway 40152s 3 groups of 16. Both combos were about 52-54 lbs, but the 40152s give me 45AH but have a 15C rating for a total of 675A.
My KTM is controller limited to 400A now, because the motor is rated at that. The first motor I had in the KTM was an ME0909 rated at 200A, which I ran at 400A, because my batteries could, and it melted the brush blocks after a while. It only had 4 brushes, which are replaceable. No harm no foul. Then I went to my current motor, new frame ( legal one), an ME1004, 400A motor. You know you can street legal any MX bike if you make it electric in Cal, at least a few years ago. I did. But as soon as I get the Yamaha finished, I have some upgrade mods for my KTM, and one of those is to raise my controller limit from 400 to 500A.
I have been looking at the Headway 38120HPs but you pay a weight price, to get but I love the bolt together cells
Here are some pictures of my old Prismatics, and their BMS, and my newer 40152S's without BMS. That is going to be another mod to the KTM.
The first image is not finished, it needs 3 more cells in the rear. But it has the ME1004 motor. The second pic is the the first bike with all 16 cells and a ME0909 motor. The third pic is 40152S's and ME1004 ( same boot drying in the background as earlier pictures...)

 

[Mark911]

My experience is that 1mm solid copper wire at the lengths here (about 18mm) should be good for way more than 30 amps. More like 200. A direct short in any particular series string can easily produce this current.

 

[DonCox]

Mark, Thanks for the information. You made me think hard on all the different current charts out there, and special charts for every application. There are really none for our world. There is one that refers to Ampacity for Nickel and all metals as well as resistance.
https://www.endless-sphere.com/foru...id=160233ce6213bb6db14a6b610d195c44&mode=view
My 1mm fusible links(???) have a cross section of .785sq/mm which says AWG 19 and about 13amps in copper.. And you say it should carry about 200A
So I said, how can I do some current checks, and I have a way. And you are closer to the correct answer.
Here is what I did. I have an Electric KTM. I have some neat new Current/ Voltage meters for my new Yamaha build, and I never actually measured the current on my KTM, so I installed it temporarily on my KTM . My bike draws 375A and started at 53.6V and moved all around.
Then I inserted different wire sizes in place of my 2mm Cu fuse and recorded the current they dropped out, or where they melted.
1.25mm Cu wire blew at 270A
.90mm Cu wire blew at 156A and 175A (two tests) This is the actual wire I used.
.60mm Cu wire blew at 60A and 77A
.74mm Al wire (.030" mig Al wire) 75A
I learned something else in this process. The 1.25mm wire soldered onto larger 2mm melted the solder at about 240A. The .90mm wire solder to larger wire, melted the solder at about 160A, before it blew the wire.
What all this tells me is my .90mm wire are not fusible links, but there will not be as much heat build up, there. And the 2mm bus bars will work as well. No heat, will not melt the solder joints.
So thanks for pushing me to do the test.
The meters I bought are very lightweight and easy to install.
https://www.ebay.com/itm/DC-0-300V-Battery-Monitor-Meter-Capacity-Voltage-Ammeter-Coulometer-Hall-Sensor/383480311701?ssPageName=STRK:MEBIDX:IT&var=651889823387&_trksid=p2060353.m2749.l2649
I got the 300V 400A model.
Here are a few pics
1st pic Original fuse and serup.
2nd pic One of the soldered fuses with the Hall Effect Current Measuring coil.
3rd pic Is the new Meter mounted.
4th pic is a melted fuse

Thanks for the information, causing me to dig a little deeper.
Don

 

[Mark911]

Actual testing is always better than mathematical or analytical analysis. Good work. When I was testing copper fuse links I was shocked as to how much current a tiny cross section of copper wire can take before heating to the point of melting. In addition to X-Sectional area, length and termination conditions were also very critical. The shorter the conductor the higher the amps required (makes sense, lower resistance = less heating). The termination condition surprised me a bit. If the end/ends were connected to a relatively good heatsink (like the cell itself or other more massive conductor), the heat transferred was significant enough to raise the current required. Collectively, I'm talking about how even a few thousands of an inch or a minor change in heat dissipation result in significantly different fusing points. I concluded that the tolerances required along with the needed accuracy and repeatability of the manufacturing process for incorporating a "true" fusing system was just too difficult. Better off erroring on the large side and just hope your cell screening process finds any bad cells before they make it into the pack.

 

[Mark911]

Don,
Im curious why you decided to go from your Headman type setup to 18650s in your Yamaha project?

BTW, here's a picture of 1 of 2 modules I built for our KTM 65 conversion.

 

[DonCox]

Wow, your battery build looks so professional. And so does the bike. I wish I had the resources of a machine shop. let alone that spot welder. Mine is a garage build.
Why going away from the Headway to 18650? Weight and size. Just rough estimates to get 72V 675A out of the 40152S's was about 76lbs. 18650 x 420 cells is about 54lbs. I am just using the battery weight, all the outside stuff adds about 10%. A 40152 weighs 480g x 72cells. But you saw half of 48cells in that one picture on my KTM. There is a lot of waste space. I don't think I could fit 72 cells in my frame. Lipo pouches might work better on the space, and they are a little less weight, but information isn't readily available . I looked at the Headway 38120HP, Headway 38120HP 8Ah LiFePO4 cell, and you would need 96 cells in four packs of 24. 64lbs
I made up mock up battery packs for these, and couldn't get them to fit in my YZ250F 2008 frame. A friend in Florida, who built with a newer YZ250F frame, and it has a lot more space in the upper Frame area, and it looks like a ALTA battery would almost fit. If I were to be starting a project, I would look at that frame. By the way did you see the 2021 Yamaha electric ad? It looks like they built around that frame.
2021 Yamaha YZ Electric Motocross Bike First Look
But back to the Batteries. I like the Lipo cells for there ease of putting them together, bolt together. and they are so durable. I got a good 4 yrs out of my first set of Prismatics, but they stop manufacturing the 10C model. So I tried some pouches and the Headways to replace fallen cells. The pouches were lighter, but a pain at that time to solder together. I then tried the Headways and liked that ease of construction and bolt together. So that was my direction for then. But my friend in Florida and I could not find a replacement for the Sony VTC6 cells used in the late model Alta's, for size and weight. They are just a pain to put together.

 

[Philip]

By the way did you see the 2021 Yamaha electric ad? It looks like they built around that frame.

Yamaha Europe is working on a full size e-MX bike!

 

[C5tor]

I see ElectroBraap just posted a new vid.