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Discussion Starter #1
Hello all,


I'm new here on forum (from writer side), but old visitor and from here I had desire to make my own conversion. My base car will be BMW 116. Electric motor will be from Leaf with controller from Johannes.
Battery pack will be about 48 cells from Leaf pack or double 48 pack with full pack voltage about 200V (4.2x48) so around 177V nominal.
And now main question: what power can I expect if Leaf motor will be on gearbox from BMW or connected directly to drive shaft.
I hope with this voltage I can get about 2500rpm so with gearbox and IV shift will be about 100km/h. Power from Leaf motor will be enough?


Regards,
Damian
 

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The Leaf's wikipedia page specifies a 7.94:1 ratio.

Taking a listed top speed of 93mph and a 217/50R17 tyre, I calculate the wheel turns at 1227rpm, so at top speed the motor speed is 9745rpm. At 70mph, the motor speed should be 7335rpm.

I would investigate using the Leaf motor and gearbox in their original front-drive layout. If your 116 is an F20/F21 (2012 onwards), this generation was offered with the xDrive 4WD transmission, so you just need custom driveshafts. If your 116 is a 2004-2012 E81/E87, these were rear-drive only. I don't know whether the front hubs are the same or similar enough that you can swap in the later generation's xDrive front hubs.
 

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The leaf battery uses 192 cells, 48 modules containing 4 cells each, arranged 2S2P. The voltage I can find is 360V, which would mean the modules are all connected in series, with 3.75V nominal cells.

Is your plan to use 48 modules (or 24 gen2 "double modules"), or actually 48 cells (12 early modules or 6 doubles)?
 

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The leaf battery uses 192 cells, 48 modules containing 4 cells each, arranged 2S2P. The voltage I can find is 360V, which would mean the modules are all connected in series, with 3.75V nominal cells.
That's correct. :)

Battery pack will be about 48 cells from Leaf pack or double 48 pack with full pack voltage about 200V (4.2x48) so around 177V nominal.
Is your plan to use 48 modules (or 24 gen2 "double modules"), or actually 48 cells (12 early modules or 6 doubles)?
That's a good question. The voltage calculation suggests 48 cells in series, which would need to be 24 modules and so 96 cells, or internal rewiring of the modules (which no one does).
 

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Discussion Starter #5
The leaf battery uses 192 cells, 48 modules containing 4 cells each, arranged 2S2P. The voltage I can find is 360V, which would mean the modules are all connected in series, with 3.75V nominal cells.

Is your plan to use 48 modules (or 24 gen2 "double modules"), or actually 48 cells (12 early modules or 6 doubles)?

Exactly like you wrote, I want to put my motor on 24 modules containing 4cells (2S2P), so voltage will be 7,5V*24=180V nominal. In case of small distance later I can connect second 24 modules pack to double capacity but main question is to persons who tried with this motor.
What speed and power can I expect with half voltage from original Leaf and if is better or worse to go with/without gearbox.
 

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Discussion Starter #7
Good to knows, that someone did this but I think it will be to big deal to me and probably I will take worse result (acc. and speed) than make rewind.
In donor is manual gearbox with 6 gears forward, so on first conversion stage I prefer to join motor with gearbox and look at results.

I think if I will get about 2500-3000rpm in car, for me will be enough, but what will be with acceleration - it is question to all of You who maybe tried this.
 

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With half of the voltage for which the Leaf motor is designed, you won't be able to use the upper part of the motor's speed range. With any luck, you will still be able to get the full rated torque of the Leaf motor and low speed, and maybe even the full power at moderate speeds. Although a multi-speed transmission is not normally needed with a motor like this, changing gears might allow you to keep the motor in the speed range it needs to be for sufficient power on the lower battery voltage.

One issue will be that half of a Leaf battery pack may only be able to deliver half of the rated power reliably. It's not clear what limits the Leaf's peak power in stock form, but it's not likely the motor - it may be the controller (inverter), or it may be the battery (with the controller programmed to not exceed the battery's safe power level).
 

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Discussion Starter #9
I hope You're right. If on full voltage 380V motor have about 8000rpm, so on half voltage if torque will be the same the half speed should be enough.
 

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iirc forum member arlo is reporting 15,000 rpm on ~460V with field weakening using the Lebowski controller chip and his own power stage. On that basis you should be able to reach in the order of 5800 rpm provided the huebner inverter field weakening works as well as that obtainable with FOC.


I will be interested to see how you achieve motor to gearbox coupling. I have a similar project connecting a second gen leaf motor to the ZF 5 speed on an e36 328i. My current plan is to use a single shaft internally splined rather than welded together parts. With my diff ratio leaving the transmission in 2nd gear gives me just over 8:1 ratio which is quite close to the leaf transmission reduction so it should perform ok.
 

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Discussion Starter #11
I have plan to connect motor shaft directly to gearbox shaft with welded joint (like mix of Fiat Multipla clutch disc and original clutch disc from BMW and elastic element between them)
I think it will be enough to go forward :)
Another thing is plate. For this I will use 3d measuring arm to take axis center and motor montage holes from one side and axis center with holes in gearbox. Then I will make plate with holes from both sides.
 

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I have plan to connect motor shaft directly to gearbox shaft with welded joint (like mix of Fiat Multipla clutch disc and original clutch disc from BMW and elastic element between them)
I think it will be enough to go forward :)
Another thing is plate. For this I will use 3d measuring arm to take axis center and motor montage holes from one side and axis center with holes in gearbox. Then I will make plate with holes from both sides.
Have you been able to verify that the Multipla clutch disk properly matches the spline on the Leaf motor? I'm still working through some coupling issues, and that looks promising.
 

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Discussion Starter #13
Hello,


So I did trial with Multipla 1,6 16V clutch plate and is similar situation like with Samurai plate (maybe little less):
https://youtu.be/rNISAE1mXzM
Looks good and for trials with be enough, but I think for longer using I have to found something with smaller space between splines.
Do You need some pictures or video for comparison?
 

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I'm interested in the problem of poor fit of clutch disc centres for my own project. I want to repurpose a VW gearbox for a classic Mini conversion, but there's too much slop in the centre of the original clutch disc. I'm going to try nickel plating the clutch centre to get a better fit. Not sure how durable this will be but I'll report back if successful.
 

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I'm interested in the problem of poor fit of clutch disc centres for my own project. I want to repurpose a VW gearbox for a classic Mini conversion, but there's too much slop in the centre of the original clutch disc. I'm going to try nickel plating the clutch centre to get a better fit. Not sure how durable this will be but I'll report back if successful.
Here are other ways of dealing with a loose spline joint, posts 93-98 :https://www.diyelectriccar.com/forums/showthread.php/nissan-leaf-motor-coupler-192026p10.html

The nickel plating probably would be too soft. Building up the surface with hard chrome might be a better option.
 

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Re the fit of the clutch splines

If you are using it the same way that it is used in the IC system you should not have a problem - there were a few of those VW's built! - and that does not seem to have be one of their problems!

The only way that it would be a problem would be if the flywheel (if used) was bolted to the wrong side of the splines
 

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Discussion Starter #17
So I think for now probably I will let to use this not-so-good clutch disc. This will be also only donor of spline, because will be welded with elastic clutch one side part and from BMW gearbox second side with BMW clutch spline part. So in fact it will be hybride between 2 clutch discs (multipla-bmw) and elastic clutch inside.
 

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I have plan to connect motor shaft directly to gearbox shaft with welded joint (like mix of Fiat Multipla clutch disc and original clutch disc from BMW and elastic element between them)
I think it will be enough to go forward :)
Another thing is plate. For this I will use 3d measuring arm to take axis center and motor montage holes from one side and axis center with holes in gearbox. Then I will make plate with holes from both sides.

By a 3D measuring arm do you mean one of these?:https://www.youtube.com/watch?v=3Y1-nXuZU2k It is good to see these getting less expensive and in more common use.

Also, does your transmission input shaft move like this (also read the UPDATE in the comments below the video) ?: https://www.youtube.com/watch?v=OCLC47pAE6s

If yes, you need to use some kind of pilot bearing or support sleeve on the end of the input shaft similar to what was on the original ICE. This will support the shaft and keep the gears and bearings aligned inside the transmission.
 

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Discussion Starter #19
Hello all,


I have done all 3D measurings of Leaf motor plate and my E87 116 gearbox plate. Yes, You have right also on my gearbox input shaft moves, so we will design plate with bearing. For now I think I need to do also elastic clutch with closer splines instead to Multipla.
 
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