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I got in touch with the person who made this Mini conversion and he says the car does ~70mph with a range of ~60mi with plenty of torque. According to the photos, that's with 17 modules, which would be ~128V nominal.
But the update is
Edit: Yep, it seems they're running 29 modules for around 220V, limited to 70% torque (either by batteries or the custom controller, I don't know).
 

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Discussion Starter · #82 ·
Yep, I'm starting to get my threads crossed.

In any event, a 24 module half-pack will get the car moving, and that's all I need to get legal and dawdle around town a bit. Saves me some soldering and wrestling of battery packs and I can find out the real limits of the system in the real world. :D
 

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Discussion Starter · #83 · (Edited)
As I try and find a local fabricator or race shop, I drummed up a less ridiculous set of measurements...Still quite rough. The inverter need not be mated directly (though it is handy for it to be, and there is space even in a mini), but if it is it adds about 6" of height.



 

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Although rough, these measurements should be very helpful to people planning conversions. :)

In the first photo (from behind), I assume that the vertical dashed line is in the middle (left-right) of the drive unit... but not the centreline of the Leaf. In the Leaf, the motor is substantially offset to the right side.

The right-side output is interesting, because it is designed with a steady bearing so that it can use a long stub axle, and shorter half-shaft. If the drive unit were centred this would be great - allowing for equal-length half-shafts, but in the Leaf it just makes the right side half shaft shorter, with no clear benefit. In his truck, CanadaLT28 is placing the drive unit on centre (that is, just fitting between subframe rails equally spaced from centre), so this works out well, with long half-shafts of nearly the same length. It looks like the drive unit will need to be centred in the Mini just to fit, so half-shafts will be equal or nearly so.

I assume that the last photo is the stock Mini front subframe. Wow, is that close... perhaps it could be used with modification (such as the front bar being replaced by something that curves forward, but once one is modifying it would presumably be easier to work with the tubing of an aftermarket subframe.
 

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Discussion Starter · #85 · (Edited)
Correct! All of my measurements are focused around equal driveshaft lengths and angles in the hopes of minimizing torque steer. I'd rather cut and reinforce the subframe than relocate the axle outputs to off-center, if at all possible. I can fall back on an aftermarket subframe if need be, but I'd rather stay stock if I can.

It does not seem like the body will need any modifications at all. There is fair clearance on the right side if the subframe is cut out. The real sticky bit is that the motor will need to be 1-2" forward of wheel center in order for the gearbox to clear the steering rack (which is millimeters behind the subframe). I'm hoping the only downside is mildly accelerated CV joint wear...

I'm not quite sure what to do about axles. I expected to have a set made for about a grand by giving someone who makes axles some specs, but I'm not sure that's in the cards (or at least, I'm not sure where to look). Most fabricators don't like to weld axles because of the alloys involved. I dunno. I'm still asking around. Gotta make sure the motor fits, first!

 

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Hi
I would be looking for another Mini front subframe - they used to be 10 a penny!

Then you could cut and shut on the scruffy one until you are happy with it before modifying your good one
 

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You should be able to sleeve the shafts as I've done it before on a couple of 16v builds.
Im currently finishing my hyper 9 mockup and then I can start cracking on looking at mounts using a standard subframe.
Have a look over at the 16v mini forum for subframe designs. It should give you an idea what you can get away with.
 

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Discussion Starter · #88 · (Edited)
Some progress. I wired up the BMS and can successfully get the voltages of each of the 48 paralleled cells in my brick of 24 modules. It was a bit tedious. Unless I'm mistaken, Nissan labels the cells from 1-48 starting from the module that is the most positive. Thunderstruck labels the cells starting from the most negative. That confused me for a bit.

Thunderstruck also wants the "W0" wire on each BMS harness to be attached to the W13 wire of the previous harness in the group. It makes sense, but also involved some head scratching. First tap is pack negative...The first tap in the next group is that last tap of the previous group...Last tap is pack positive.

I'm now faced with a bit of a dilemma: The charger I bought was intended for a full pack, but now I'm trying to use only half to see how it goes...The charger's minimum voltage output is 200V. The total voltage of my half-pack goes from 158V to 202V (from 3.3V to 4.2V).

I'm wondering to what degree I can charge this pack with this charger...Even if it takes a long time, or I can only do it in bursts, I'd rather not mess with it until the car is on the road, but I don't want to stress anything out!







Code:
bmsc> show cells
 c1 - 3.859v        c13- 3.860v        c25- 3.858v        c37- 3.863v +     
 c2 - 3.862v        c14- 3.861v        c26- 3.862v        c38- 3.863v +     
 c3 - 3.856v --     c15- 3.857v -      c27- 3.862v        c39- 3.862v       
 c4 - 3.863v +      c16- 3.862v        c28- 3.860v        c40- 3.858v -     
 c5 - 3.858v        c17- 3.860v        c29- 3.860v        c41- 3.860v       
 c6 - 3.865v ++     c18- 3.858v        c30- 3.863v +      c42- 3.863v +     
 c7 - 3.859v        c19- 3.855v --     c31- 3.861v        c43- 3.862v       
 c8 - 3.863v +      c20- 3.862v        c32- 3.864v +      c44- 3.860v       
 c9 - 3.864v +      c21- 3.860v        c33- 3.857v -      c45- 3.859v       
 c10- 3.863v +      c22- 3.864v ++     c34- 3.862v        c46- 3.863v       
 c11- 3.857v -      c23- 3.862v        c35- 3.855v --     c47- 3.863v +     
 c12- 3.862v        c24- 3.861v        c36- 3.860v        c48- 3.859v       
bmsc> show map
 ltc|pack|group| cells
----|----|-----|----------------------------------
  1 |  1 |  1  |(c1 -c12) X X X X X X X X X X X X
  2 |    |  2  |(c13-c24) X X X X X X X X X X X X
  3 |    |  3  |(c25-c36) X X X X X X X X X X X X
  4 |    |  4  |(c37-c48) X X X X X X X X X X X X
 

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More progress on the "easy" part...I cut the axles and they pried out of the gearbox easily. I dunno how I'll mate them to the Mini wheels, but I'm hoping the answer lies under the rubber boot. Once everything was out of the engine bay, the motor lifted out with ease. I've pulled my first motor.

The hardest part of this teardown is dealing with the wiring harness. I've never seen so many wires, clips, and connectors in an automobile. Very few major components are actually detachable such that it looks like I'll need to take apart the entire dashboard and center console, disconnect everything, then fish the whole nervous system forward through the hole in the firewall. I wish I knew what was unused and safe to cut off.

The prospect of getting all this stuff in the Mini is proving daunting. Progress?
You will need to splice both sides of shafts together. There is a procedure for doing it correctly. This is how you retain shaft torque capability. Just welding it is not good.
Here you can see my work:
https://leafdriveblog.wordpress.com/2019/05/11/driveshaft-extension/

Observe i did weld shafts on the circumference, however i further drilled 2x radial holes into the larger diameter shaft at 90deg apart and weld them in. First I put inner shaft in a lathe to run it down a bit so both shafts were a good fit. Then i welded the circumference and filled outer holes on the inner shaft. This way inner and outer shaft now have the torque capability of a homogenous part.
You may use an outer sleeve to join them, but both shafts have to be fitted to it.
 

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...I cut the axles and they pried out of the gearbox easily. I dunno how I'll mate them to the Mini wheels, but I'm hoping the answer lies under the rubber boot.
I never did understand why you cut the axle shafts. That's a lot of unnecessary work, and eliminates some options for using the shafts.Normally you remove the nut which retains the axle in the hub, take apart enough of the suspension to allow the hub to be pulled outward and release the axle, then pull the axle out of the transaxle. The whole axle assembly with joints on both ends and the boots intact comes out as one part.

Under the boot, all of these CV joints have the outer cup (the visible part), an assembly with balls or rollers which runs inside the cup (depending on the specific design), and the shaft with splines which inserts into that inner assembly on each end. The cup and inner assembly are a matched set but the same CV joints can be used with various lengths of shafts and various types of joint at the other end, as long as the splined ends are compatible.

I'm not quite sure what to do about axles. I expected to have a set made for about a grand by giving someone who makes axles some specs, but I'm not sure that's in the cards (or at least, I'm not sure where to look). Most fabricators don't like to weld axles because of the alloys involved...

Rational professionals avoid welding axles and steering components (such as the steering arm attached to the hub carrier), both due to the unsuitability of the materials for welding, and the consequences of failure. Axle shafts are particularly problematic because of the need for them to be straight and balanced; production axle shafts are machined from solid stock, with no welded assembly.

I assume that in the photo, the shafts are (from left to right)
  • Leaf left side, inboard end
  • Leaf right side, inboard end
  • both Mini shafts, outboard ends
The Mini shafts look (as expected) smaller in diameter than the Leaf shafts, so there is not likely any chance of machining new splines on their inboard ends to insert into the Leaf CV joints. Going the other way, there might be enough length left of the Leaf shafts (given the decrease in track dimension) to have them turned on a lathe and splined to insert into the Mini outer CV joints, instead of the stock Mini shafts.

It's hard to tell what other options might be available without seeing the other ends of the shaft assemblies, but other interesting adaptations are possible, aside from welding shafts together at the middle. For instance, in his Westfalia T3 with Chevy Bolt drivetrain, Yabert modified the inboard Bolt cups to become stub axles to which the VW shafts bolted through a flange, because VW inboard joint cups bolt to a flange instead of having a splined stub.
 

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Well of course after welding i had to do some annealing to releave stress in the welded spots. Without that welded carbon steel is brittle like glass.
There is not so much science as experience and some sense. You follow colour of heated steel vs the colour table and specific steel properties. Then you leave it at that temperature for specified time and finally slowly cool in oil.

Worked this before on some transmission shafts for tractors and other machinery.

Real danger will be me if i try to push the Leaf gearbox too much.
 

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Discussion Starter · #92 · (Edited)
Humbug. I think using the stock Mini subframe is out. The final bit was the axles. There simply isn't enough room to get the axles in and out with the motor in place (and there's no way to remove the motor with the axles in place).

The rearward motor position is the critical measurement...The axles will always be at an angle when rotating with this swap, which will accelerate wear, I expect. I don't see any way around that without cutting the body and/or moving the steering rack. Even if the subframe were completely cut away, the body of the car is directly behind it, and the steering rack directly behind and below as well.

The axle holes can be enlarged to sneak the axles through (maybe 1/2"), but not at the angle that they need. The boots might also rub the edges. The Leaf motor will be about an inch further back than what is in these photos when dropped into place, but that's it, and it's not enough to keep the stock subframe without really mangling it...I don't see any way around it without changing the suspension pickup points, and I'm just unwilling to do so.

Education is expensive.

So. New plan is to pick up an Allspeed subframe designed for a Nissan G10/G13. The Allspeed subframes use the stock suspension, have been around and steadily improving for years, are made with square tubing (which is easier for me to work with than round), and are pretty well proven in terms of strength and handling.

Compromises:

- It might wind up being $2k and two months to get this thing to California.

- The lower arms must be replaced with somewhat proprietary "spherical" lower arms. This will increase NVH a bit, but allow for greater alignment adjustment and handling precision.



 

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My tuppence worth

Just hack away at the old subframe

What I would do

I would make an external temporary frame to ensure that the right and left hand side of the subframe stay where they are

Then I would gleefully cut away everything that is in the way - using the temporary frame to keep the subframe together

Then I would add metal back to do the job of the bits you have cut away - but clearing your new power unit

Then when it's all good take/cut off the temporary frame
 

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Humbug. I think using the stock Mini subframe is out. The final bit was the axles. There simply isn't enough room to get the axles in and out with the motor in place (and there's no way to remove the motor with the axles in place).
I've been reading through this topic since discovering it this past weekend. I have had the notion of an electric Mini on my brain for a while and I have an idea that may help you.

I currently have 3 Minis with two of them being slated for Honda D16 engine swaps using a custom subframe from McGees Custom Minis in Maryland. John McGee builds round tube subframes that accommodate the Honda D16 engine/trans but still maintain the stock suspension components and track width. "Yeah, but that's ICE technology" - right, BUT there is a company that makes an electric motor adaptor to mate with the Honda D series transmission!

Despite already having purchased two subframes and two D16 engine/trans, I'm very seriously considering using one of the subframes and transmissions for an electric conversion of my '91 Mini saloon. I'm still quite green to EV tech but with what I've learned so far, this seems like a great swap. The Mini is a naturally light weight platform to start with and many other builders have proven the ability to house the motor, controller and batteries in its tiny space.

I'm 6ft tall and in order to achieve a more comfortable driving position and leg room, I'm relocating the front seats rearward a few inches (I'm using 2016 MINI Cooper S units with electric heaters). That mod makes what was already a small rear seat area completely unusable for passengers. With that in mind, I've removed the side storage compartments (front seats interfered with them) and will be removing the rear seat pan base which then makes it an ideal location for the batteries. I've even considered fabricating a dropped floorpan space in the middle of the rear subframe to house the batteries and get a lower center of gravity.

I know you've gone pretty far down the Leaf route but perhaps the Honda D series trans and subframe swap would be a better choice? The bonus is that shipping of a subframe within the US versus from the U.K. would amount to some savings...and Honda D series transmissions are still rather plentiful.
 

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Discussion Starter · #95 ·
Do you have a link for the Honda transmission adapter? I found someone was building one, but it was not, like, a purchasable product. The bigger concern is the mating the output shaft...It's gotta spin perfectly smooth at 10k RPM.


I was in touch with McGee and decided on the Allspeed, though I'm not sure I remember why anymore. I think the track width does increase a touch, but looking back at my conversations with him, he didn't answer that question, so I dunno. He recommends adjustable lower arms, too, so maybe that's similar to the Allspeed setup?

Costs and timeframe are about the same. Square tubing is easier for me to weld stuff to, but that's not a huge deal. The Honda subframes require cutting the body, which also isn't that big a deal. The real benefit of the Honda subframe is that, if I can't get the Leaf motor in, maybe I can use a CR-V transmission...which could then grow into an AWD setup in the future (for jsut a few thousand more!)...
 

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is it possible to get some more photos of the ESDI front subframe setup? That could help you greatly with saving time, the guys at london electric cars have just completed a nissan leaf conversion in a mini so they could also be worth speaking too?


Ive just got hold of a mitsubishi outlander rear electric diff, it looks as though it could be compact enough for me to not have to cut up the front mini subframe.
 

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Discussion Starter · #98 · (Edited)
I decided to purchase McGee's MCM front subframe. It uses the Allspeed towers, but allows for the use of all stock components, and provides a lot more space for the motor and axles. Unfortunately, it'll be a few months before I get it, so I'm switching gears to installing the battery and charging system.



I drummed up a wiring diagram with all the components I'm expecting with the lovely and free draw.io. I have a Thunderstruck BMS, charge controller, and 312v TSM2500 charger, and display that are all designed to work together, which is quite nice. Documentation is comprehensive, and everything is very well thought out. I plan to pick up their motor controller and DC-DC (Volt) converter as well (although I'm hoping to go without DC-DC until the car is on the road and registered).

 

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Discussion Starter · #99 ·
After getting into the weeds of the specs, it seems I'll need at least 30 modules to be within the charger voltage range (200-420v), and 34 modules to be within the DC-DC converter range (260-420v). I thought about going with a full pack, but I'd reeeally like to see how it performs with a lighter pack in the real world before I commit to all of the weight.

The goal is to put as much weight low, centered, and forward (in that order) as possible, while taking into account the fact that having batteries stashed all over the place is a pain in the ass in terms of wiring and installation...I'm gonna go with the simplest option until the car is driving and legal, and go from there.

After a brief foray with my custom Rapid Prototyping Device (RPD), I decided to just measure and do a quick (lovely and free) Sketchup diagram of some battery installation options. Each of these involves cutting out the "shelf" of the rear seat that projects forward from the "real" seat floor. These measurements aren't precise, and certain configurations would require more "massaging" than others, but it helped me visualize the configuration without clumsy boxes or lugging batteries around. The "rows" are by module count (48, 36, and 30).

The packaging of these Leaf modules is delightful. I hope they keep a similar form factor moving forward!



 

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Discussion Starter · #100 · (Edited)
I managed to install the battery pack into the car (minus extra the 6-module pack I'll need). It was an involved endeavor, utilizing my janky gantry, a shop crane, and some careful fuckering to get them all the way onto the rear seat. I'm not quite sure how I could do it differently without splitting the pack (due to the 3-foot rods that span it), but this was a precarious performance I'd rather avoid in the future. Looks like it was made to be there, though, which is nice...The pack sits on a board of wood to ensure a flat surface for the modules to span.



 
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