Yamaha YZ250F

[E-Max]

https://www.facebook.com/groups/electricmotorcyclebuilds/permalink/2556781911125831/
this person used a qs 180 90h with ND961800 pushing around 100kw! that would be pretty insane on a shifter kart
[/quote]

wow this insane!
I am not sure if the ND961800 is needed, maybe the ND961200 is enough

 

[dougf]

Doug, how do you limit the charge then? (I think you were running 24s?) Do you guard it and turn it off when it is done, or let the bms cut if necessary?
I dont think I will buy one, but I am curious anyway :wink:

I havent really tested the new gearing yet, it will probably be this weekend.

Tyson, I have seen that one before
Very cool bike, but is it possible with that short wheelbase and skinny tire?
I dont know what to make of it, if it has the track version the controller should be capable of 100kw.
When I was messing with the sevcon it seemed like the motor was limited because of its higher inductance compared to a z-force 75-7 for example.

It is also interesting that he seems to have the earlier, 28Ah version of passat gte cell modules. Where I have the newer 37Ah version, that in my limited test had lower ir than the earlier ones

A 10.2x and 210km/h run in sneakers, jeans and a sweatshirt :?

It has its own battery charger inside. When I ordered I got it made for constant current up to 100.8v, then constant voltage. When the current drops below some threshold the engine shuts off. And yeah BMS takes care of balance, although the molicels are pretty much always bang on.

So that guy is making 100kW with a 180 and a 961800? Needless to say Im skeptical. Assuming NO sag you would need to run 125V which is higher then the max voltage in of a 961800. Thats before losses due to efficency, chain cabling etc. Id say this motor starts dropping off pretty quickly after about 500 battery amps which means around 40kW before losses.

Doug

 

[liveforphysics]

That drag bike looks legit to me. 125mph trap speed and 10.4 1/4mile takes real horsepower to do, that's faster than my 180hp GSXR-1000's fastest ET.

 

[j bjork]

If it is the track version of the ND981800 it should be capable of 1350 batteryA.
It looks like he is running 2 (12s) battery modules, so that should be 24s.
Charged to 4,2v/cell it would be 100,8v.

If he is able to pull 1350A, how much would it sag, to 80v?
80x1350=108k

I think my tests on cells like that gave about 1,5mOhm resistance/cell.
That would mean 36mOhm in 24cells, and 48,6v drop at 1350A.
But that was on used cells in room temp. His might be new (I saw a post about modules from flooded new cars) and they might be heated before a run.

Even if that is possible it dosent mean 100kW output, but maybe 100kW from the battery.
I think sevcon predicted about 45kW (from the motor?) at 108v.
But if the run at the strip is real it would for sure take power..

 

[liveforphysics]

I would be shocked if he wasn't pre-heating his pack before the drag race. It helps too much not to do it.

Somehow he really ran a blazing ET and trap speed, and not possible to do that without making a LOT of mechanical shaft power.

 

[j bjork]

It is amazing with such simple stuff that you can just get at a reasonable price.
Nothing fancy custom made in the drive line from what it seems

Back to my bike:
I was out riding quite a lot yesterday, on a tricky track with a lot of rocks and roots.
But it had some faster parts too.
I am surprised again how much difference the gearing makes

I thought on this bike with so much power it wouldn't be that noticeable, but it changed character a lot.
It lost the bite, the aggression. It still has power, it just doesn't respond at all the same.
( I went from 7,1:1 to 6,3:1, a little under 13% higher or faster or what to call it)
I got more used to it after a while, and I think I will ride it like this for now.
But I think lower gearing and maybe lower phase amps would be more efficient, and probably more responsive on the throttle.

 

[Dui ni shuo de dui]

It is amazing with such simple stuff that you can just get at a reasonable price.
Nothing fancy custom made in the drive line from what it seems

Back to my bike:
I was out riding quite a lot yesterday, on a tricky track with a lot of rocks and roots.
But it had some faster parts too.
I am surprised again how much difference the gearing makes

I thought on this bike with so much power it wouldn't be that noticeable, but it changed character a lot.
It lost the bite, the aggression. It still has power, it just doesn't respond at all the same.
( I went from 7,1:1 to 6,3:1, a little under 13% higher or faster or what to call it)
I got more used to it after a while, and I think I will ride it like this for now.
But I think lower gearing and maybe lower phase amps would be more efficient, and probably more responsive on the throttle.

Get crazy, make some kind of gear swicthing system so you can get the best of both worlds!
You already have the slight efficiency loss of an intermediary chain transmission stage anyways, so you wouldn't loose anything except maybe adding a little bit of weight.
Sure would be fun to see!

 

[j bjork]

The only reason I changed gearing was to be able to use sprockets available to buy "off the shelf".
I dont have any other benefits that I know of yet, so some kind of transmission with gear change dont make much sense to me :wink:
If that is what you meant?
I suppose it will have higher top speed now, but that is not something I use anyway.

The problem was that the sprocket on the motor was too soft, it was made from ordinary steel.
I think I will check with the watercutter if he can just cut up the splines a little if I get sprockets with a smaller spline, so I can get a good 10 or 11 tooth sprocket on the motor.

 

[dougf]

That 100kw motor is probably rewound then because you're not getting 10krpm at 100vdc, or 100kw for that matter. I will try get my bike on my dyno this weekend. I should be able to do consecutive pulls while upping the battery limit. My guess is after 500A either my battery or motor starts leveling off.

The water jet guys should be able to cut you a sprocket from hardened steel. Or at least out of hardenable steel. You can always go up on the rear sprocket. I believe the biggest that will fit without modification is a 54T. The 60T i have on the back is about as big as Id go before being worried about damage from rocks and to fit it you need to lower the chain guide about an inch.

Doug

 

[j bjork]

Maybe you can reach 10k rpm with a lot of FW?
I think the qs138 on my ktm pulls to at least 8000rpm, and that is around 80v I think.
With a lot of FW that is.

I will have a talk with the water jet guy, and see if he has some suitable steel.
Last time he cut these when I had specified what steel jt use, but I think it was more like a test.
The idea with using a finished sprocket and cut new splines was to get the right hardness and the right tooth profile.

I was too curious to just leave it, so I opened up to the primary reduction after the ride last weekend.
Looks good, the 18 toot seems to be a winner

Ill wait for your updates of the dyno pulls
Dont forget to test those rpm/% settings, KI/KP, weak character etc. before you push too much on the amps :wink:

 

[speedy1984]

After setting up my 96/850 version controller i got a rated speed of 7400rpm on my v3 motor.Most people go straight into self learn very first thing when setting up for the first time.I then realised i was doing this in middle drive mode as they come from the factory,and with the percentages again adjusted in the app already you will only get the lower end on the rated speed rpm numbers i also got on middle gear.Switched into drive/high speed and rated speed then into self learn again and its now bang on what it should be.

 

[Dui ni shuo de dui]

If that is what you meant?

Yeah, that's what I meant, making a 2 speed transmission. Wouldn't be too difficult to build from what I can see on your pics, and you'd still have the same efficiency since you already have this intermediary transmission here anyway.
This way you could have a low gearing for super high torque at relatively low speeds (wheelies, burnouts and whatnot) and a higher gear for high speeds cruising at the best possible motor efficiency rpm, avoiding the use of flux weakening which is very power hungry.

The only real technical challenge IMO would be to make the axles a little bit longer to fit another gear and a selector next to the current ones. That wouldn't be necessary on the motor side since it would be possible to machine a spacer and attach it on the first gear, but that would be necessary on the secondary shaft since the selector would have to be able to slide on it.

I would definitely try that if I had the same system you have right now, would be a really fun project and a great technical challenge. Just a thought of course, I don't think you'll do that anyway but I had to propose it since your system is so well suited for this ! :wink:

 

[amberwolf]

Yeah, that's what I meant, making a 2 speed transmission.

How about something along the lines of Thud's 2-speed dog-clutch system?

Info in this thread on 2speeds:
https://endless-sphere.com/forums/viewtopic.php?f=28&t=8644
drawings
https://endless-sphere.com/forums/viewtopic.php?f=28&t=7832&start=30#p309846
https://endless-sphere.com/forums/download/file.php?id=72230

 

[tylerwatts]

I thought the exact same as amberwolf, Thud's 2 speed dog engagement. I'd put a throttle cut out on the shift lever just so it coasts when shifting, or even 2 way to speed match going up or down [emoji6]

Low/hi sounds like the ultimate tool for trails, torque in technical section then smooth speed on the open sections also. Would require less field weakening also which is handy.

Come on J you know you need to. Maybe build a snow machine for winter [emoji16]

cheers
Tyler

 

[j bjork]

Okay, a bit of guessing and assumptions but here you go:

I would guess 90% of my riding is under 60km/h, defiantly under 70km/h.
Another guess is that at those speeds I wont be in fw even with one of the lowest gearing's I can get.
I dont do "high speed cruising" or any other cruising really.
Change gear to stay out of 2 seconds of fw now and then?
I really dont see any reason to have more gears on a bike like this, maybe on a street bike.

Anyway, getting ready for competition tomorrow:

It is a team competition, two in each team. You change rider (and bike) each lap.
Should be perfect for me, then I will have time to change batteries between laps
Maybe even sit down 5min when I'm done..

 

[dominik h]

I really dont see any reason to have more gears on a bike like this, maybe on a street bike.

Anyway, getting ready for competition

Keep it simple and have fun tommorow

 

[j bjork]

Back from "Kolmårdsracet", it was a partly pretty tough track.
Especially a rather long, steep and rocky climb that continued with a short muddy part and then more rocks..
If you didnt get stuck in the climb all by yourself, there would probably be a bunch of other people getting stuck or fall in front of you.
When you made it up the hill, exhausted thinking it was over the hammering just continued for another km or two

 

[j bjork]

Last weekend I broke a bracket for the handguard:

I welded up a new top part:

But it was a really "dirty" material.
I tried to boil out the impurities, but was only partly successful.
As you can see there is a lot of pores still. I will just have to wait and see, it survived today's ride at least :wink:

There has been a few rides since I chanced gears, so I decided to have a look.
I have got a very slight slack on the chain, everything looks like new
I removed the paper seal on the motor and went back to silicone.
I dont think I will have to adjust it again anytime soon.

I made a cork seal tor the lid this time, it seems to work so far at least.
I still want to be able to check now and then :wink:

 

[j bjork]

It was time for a rebuild of the suspension.
The fork has been leaking recently. I have been cleaning the seals, but it has started leaking again.

The suspension guy wanted my help with other things, so I thought it was a good idea to leave the stuff to him

The fork got 3mm spring preload, softer compression and a thinner oil.
(New seals, bearings and that kind of stuff too of course)

The rear shock got some changes to the high speed compression, I think it got some other changes in compression and rebound as well. And a thicker oil.

Still on standard springs. I think it will need stiffer springs, at least in the rear. But I will try it like this first.

A little therapy work for me wile I was waiting. Cleaning and re-greasing the linkage bearings :?

 

[j bjork]

It was bath time at the tracks last weekend.
There was a lot of big and deep puddles of water in the mountain parts and very slippery in the muddy parts.
My friends girlfriends bike had an opening at the air filter and took in water, they didnt get it running again until yesterday..

The electric just took it though without complaining
It was damn cold in the water, I think it was 6-7degrees outside. The water was probably colder after the night :|

My welded bracket to the handguard didnt last.
It was no big surprise, I noted that it was really dirty material when I welded it.
I didnt realize it turned out quite this bad though :lol:
Well, I made another one. Hope this will work better.

 

[JRP3]

More air pockets than metal :lol:

 

[j bjork]

I think today was the first time I really hit full throttle on the bike
There was a long, relatively smooth strait with good traction on the track I was today.
First time on full throttle it cut out. I tried again next lap, and it stutters like it misfires.

Before the next lap I changed my Ki and Kp, I had low 4, mid, 4, high 6.
I changed to low 2, mid 2 and high 4. It still stuttered, but it was better.
I then changed high to 3, but haven't tested it.

It sure has some power anyway

 

[j bjork]

I got my hands on some more cells that I could test:

A discharge curve from 4,01-3,3V.

From 4,01-3,3V I got 30Ah
From 4,099-3,3V I got 33,054Ah
From 4,15-3,3V I got 34,446Ah

These cells have 62500km on them, so they might have lost a little compared to the ones I have.

Anyway, what I have now is 30cells that I can only charge to 4v/cell, that is 900Ah or 3330Wh.
If I could run 4,15V I would have 1033,5Ah or 3824Wh.

If I change to 29s and still push the overvoltage limit at 4,15v/cell I get 999Ah or almost 3700Wh
If I go low at 4,1V I still get more than now at 957Ah or 3540Wh

If I go for 28s and dont have to push any limits at 4,15V I get 964,6Ah or 3569Wh
I can get a little more if I push the cells to higher voltage, but I dont think I want that.
29s looks like the winner to me, and 30s is really the worst option when I am limited to 120,5V.

(The amp hour numbers are what I would have if the cells were parallel and only for reference, not for real)
I should either get a controller for higher voltage or cut out a cell, I have to make a decision

 

[speedy1984]

I would go 29s at 4.13 per cell if you have found the Fardriver behaves fine at 120v.Are you not using regen at all on this build then?

 

[j bjork]

I usually charge to 120,5-6V, it then usually drop to 120,3-4V before I get to the track.
I use regen, but I can only choose between slide regen or regen with a button.
I use slide now, but even if I use the button I dont get more than short peaks of 40A maybe?

I have so far never been to a track that starts with a lot of braking, so it so far never been a problem.