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Working on a 1989 Classic Mini EV Conversion

12556 Views 80 Replies 10 Participants Last post by  scottherrington
Hello Everyone,

Starting work on my 1989 Mini. Thinking of keeping the original gearbox and mounting a Hyper9 motor directly on top of it. Using SilentSync sprockets and belt as a drive system. Have something similar to ´s conversion in mind. But interested in using the Hyper9 9 and some Tesla modules from the get go.

Also considering the EV Europe system:

I have no advance knowledge in EV conversions so I want to keep everything as simple as possible for this one.

Interested in getting some feedback from you guys who are the experts. Let me know your thoughts.

Am I in the right path or is this combo I have in mind a not so good Idea.

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Thinking of keeping the original gearbox and mounting a Hyper9 motor directly on top of it. Using SilentSync sprockets and belt as a drive system...
I understand wanting to keep the original powertrain mounting and axles, but the Mini engine and transmission setup is very undesirable for conversion to an electric motor. The consensus seems to agree with Tremelune: use an aftermarket (or modified stock) subframe to mount a more suitable transaxle, or to use the entire drive unit (motor with transaxle) salvaged from a typical production EV.

The electronics package mounted directly on top of the motor is a tidy setup for many vehicles, emulating the shape of a typical engine which is being replaced, but it looks very tall to put in a Mini, especially stacked on top of the transmission. I would check dimensions carefully.
Stumbled with this option online:

Size seems manageable, price wise seems similar to what I had in mind. Will the Shafts be an issue? Should I go for the limited slip diff? Using this system with other components non SWINDON could be challenging?
That looks like a nice package. Not much different from typical salvaged EV drive units in design and performance, but potentially easier to work with... but that's why they need to describe inverter options and support use of any aftermarket inverter/controller, as well as to document the axle outputs and support the use of various inner CV joints. It's a lot of money compared to a salvaged unit if you are stuck with their controller and it isn't easy to use, and if you are required to custom-build axles.

It's unlikely that Swindon builds any of this - they have presumably just contracted with a motor supplier and a gearbox supplier (and an inverter supplier), but that is useful to the DIY builder if it makes it possible to buy one of each at a reasonable price, since most of these products are only available in production quantities.

I haven't checked the dimensions against the Leaf unit, but I assume it's a reasonable size. It also has substantially lower torque but the same power, which means that it doesn't produce the rated 80 kW until about 5600 rpm - twice the motor speed of the Leaf motor, because it has half the rated torque. That's okay for a small car such as the classic Mini, but anyone considering it for another application needs to think about that. It can't run any faster than a Leaf motor, so simply choosing the higher gear reduction ratio is not a solution if you need to achieve highway speeds.

See if you can get a subframe and axles, too...They build these things (but charge six digits):
I just got confirmation they will be selling shafts and a subframe.
There's the problem: they probably have no intention of actually selling any of these, other than as part of a complete conversion. Since they have the parts (to do the conversion), they threw together a marketing brochure for them, in case they might sell a few that way. If you need to use their shafts then they (and their cost) should be considered as part of the package, and the drive unit isn't as useful for other vehicles.
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This is a CAD dwg just for size reference.
I’m really leaning into this solution.
It's interesting how much more robust the final drive of the Swindon-supplied unit appears to be, compared to the original Mini bits. It does look promising.
I have converted my Mini with a 27kW-powertrain (from a Th!nk as donor car). With these 27kW I can make the front wheels spin at any time I want (sometime I fail to avoid it) from zero to approx. 60km/h. Top speed is 105km/h, because I have limited the max. rpm of the motor (AC, asynchroneous) to 10.000 1/min. Some people tell the motor can do 12.000 1/min, maybe I will try this some day. The car makes a lot of fun!

To me it appears not reasonable to install a 80kW-engine into a 680kg-Mini with a front-wheel-drive. It might make sense if you build a RWD- or AWD-car, or if you want a top speed far beyond 180km/h.
Does the Th!nk have, by coincidence, a 27 kWh battery and a 27 kW motor? The specs that I have seen show a 27 kWh battery and a 34 kW motor.
Although 80 kW is more than enough for a Mini, an EV converted Mini will be heavier than the original version, and it's not unreasonable compared to higher-performance modern vehicles.

Many years ago, when Ford put a then-unprecedented 220 horsepower engine in the front-wheel-drive Taurus, discussion broadly concluded that about 200 hp per ton of gross vehicle weight was manageable with front wheel drive. 200 hp is 150 kW, and the converted Mini will weigh about a ton, so with 80 kW it's way short of being unmanageable. It is, of course, both more powerful than an original Mini and more powerful than necessary to be enjoyable.
what will you be using the mini for? if you are going to go for track use then an LSD will help. Otherwise its not really required.
I agree, basically - if it is not used for aggressive driving (track or not), limited-slip is not necessary. It's not even desirable, since any mechanical LSD inherently applies too much torque to the tire on the inside of a turn and fights the desired turn. This is true even with rear wheel drive, but an LSD is particularly undesirable with front wheel drive, which is one reason that LSDs are much less commonly used in the front.

I’m aiming for a daily city driver which I can occasionally use to drive to a weekend spot 100 miles away, charge overnight and drive back. 80 mph is the objective top speed. Will be making some changes to the mechanical side to make it a more comfortable daily, need the components to be reliable and provide the speed and performance needed for the short weekend trips. Thought the LSD could help with axle shaft/tire wear and help with traction on the “High speed” highway weekend trips.
None of that suggests a need for LSD. It certainly won't help with wear of anything, unless your idea of highway driving involves spinning the tires.
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OK, so if I’m going with the Swindon HPD E POWERTRAIN I have a couple of options and I would really appreciate your thoughts on both topics:

1) MCU: 144V Curtis 1239 or RINEHART 400V PM100DX.
With the same motor? It seems unlikely that a motor which is suitable for 400 volts would provide decent performance over a wide speed range with only 144 volts. The torque (and power) curves on the product web page confirm this - I can't think of any vehicle for this which this powertrain would be useful with the 144 volt configuration.

Of course, to get anything like the published 400 volt performance, you need close to that battery voltage.
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Thanks @brian_ and @pickmeup for the info.

It’s the same 80kW motor. I will be going for the RINEHART 400V and no LSD. Battery wise I have 5 X Tesla Module 24V 250Ah 5.2 kWh in mind.
That makes sense, except that regardless of the inverter you still won't have enough voltage available, because of the battery choice. The controller/inverter does not step up voltage (except in the rare case of some Toyota hybrid vehicle controllers that have a voltage doubler ahead of the inverter stage), so what you can get to the motor is limited by what comes out of the battery. Performance will be worse than shown for 144 V, because voltage is even lower.

This assumes that you are not modifying the Tesla modules. Converting them to 12S and using 10 would give you about 225 V (nominal)... still not enough for best performance, but maybe okay.

Note: the Tesla modules have a nominal voltage of about 22.5 V (so 5 modules would be 113 V), with actual module voltage varying from as low as perhaps 18 V to as high as 25 V or so at full charge. People who think everything in DC power must be a multiple of 12 volts tend to round this up to 24 volts, but these are not lead-acid cells so nominal voltages are not a multiple of 2.
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I've been reading on this modification to the tesla modules, however it seems to be to much input and just half the solution.

Any other suggestions for this issue?
Different modules.

The ~60 V example is presumably the 16S LG Chem module designed for the Chrysler Pacifica Hybrid, and sold by various EV conversion companies. You would only need six for 360 V nominal; that would peak at close to the 400V inverter limit at full charge, but only give you about 16 kWh. That is typical plug-in hybrid rather than EV capacity, but might be enough for the Mini. If you can't fit in six of those, I don't know how you fit in five of the Tesla Model S/X modules (since the LG modules are only 3/4 of the volume of the Tesla modules, and the longest dimension is not much more than half as long), but what fits in is to some extent a matter of how the rigid dimensions of the modules go with dimensions of the available spaces.
Might still be good by putting a Tesla module or two between the front seats and one or two in the boot.
A Tesla Model S/X module is 302 mm (one foot) wide, so standing on edge it would be 302 mm tall, plus the housing. Would you really put that between the front seats? Two of them would be 160 mm thick, plus the housing - that's a lot to go between Mini seats, too.
Yup, thats it. 6 I could fit. Ideally I want 20kWh for the mini
If you were thinking of 8 modules to get that 20 kWh... no, that won't work, because the peak voltage at full charge would be way beyond the controller's 400 V limit. That controller limit is designed to work with typical 96S battery configurations, not the 128S of eight of those 16S LG modules.
Right - you mentioned that before, but I forgot that and assumed the usual Tesla Model S/X modules. Of course the 184 mm height of these Smart ED modules would be much more appropriate between the seats than the Model S/X module on edge. Maybe a stack of two could be tolerable...
I’ve been looking for different options regarding Air-conditioning? Some seem far more expensive than others. Wonder if its possible to use a unit from a Leaf. Want to be as efficient as possible. I saw a similar unit to the one below being installed in a EV Conversion in the Vintage Voltage show, however it seems really expensive.

Interesting... that one uses up to 50 amps of 12 V DC power. If the 12 V DC is coming from a DC-to-DC converter, it would seem more optimal to use the power directly a HV battery voltage; however, even 50 A @ 12 V is less power than I expected. Given that it's for a 911, and is intended to improve only on the likely marginal system in a half-century-old sports car, it might not have a lot of cooling capacity.
Stock was 1,575lb 64/36.
EV setup with leaf: 1,650lb 56/44

Is this really a bad thing? What am I missing?
It's not terrible in either total mass or front/rear distribution, but the rear mass is all overhanging beyond the rear axle line, which is undesirable for handling response in a short-wheelbase vehicle. Also, the driver and any passengers are behind the midpoint of the wheelbase, so weight distribution will be more rearward than the empty values.
... it was my intention to equalize front/rear distribution to a certain degree. Cornering ability, especially through roundabouts, has become spectacular. However I have limited acceleration (nominal 27kW only!) because front wheels are spinning.
I consider my car's current balance as a mistake, meanwhile.
Next project will have it closer to stock.
I agree, unfortunately. A car with equal load on front and rear axles and two wheel drive should certainly drive the rear wheels, not the front.

Production EVs adapted from front-wheel-drive conventional vehicles have some of the same problem for the same reason of replacing a front engine and transaxle with a lighter motor and transaxle plus battery centred behind the midpoint of the wheelbase. The original Nissan Leaf's odd rear shape wasn't just the funky French-Japanese styling - it minimized rear cargo capacity and rearward length of the cargo compartment to avoid overloading the rear axle; it even has a completely empty space under the rear cargo floor where there should be a spare tire well or hidden cargo compartment, but they didn't want any more load back there.
If find it interesting that the Swindon conversion, now that it has reached commercial product stage, places a 12 kWh battery pack right on top of the motor. The resulting weight distribution will be even more front-heavy than a stock Mini, and if someone used that pack plus an additional rear pack (or two custom packs of similar total capacity and locations), the weight distribution would probably be reasonable.

Most conversion components, whether a conventional transaxle plus typical motor or a more integrated electric drive unit but from a larger front wheel drive car, will not leave enough space for a battery pack on top.
Must be a very (!) compact battery. On the current project, I managed to install 8kWh only on top of the motor.
This is an excellent point - there really isn't enough space there for a battery which either holds 12 kWh of energy or can effectively power an 80 kW motor, let alone both. Plug-in hybrids have relatively power-dense batteries of about this capacity, and they're much larger (e.g. Chevrolet Volt, Chrysler Pacifica Hybrid, Mitsubishi Outlander PHEV); battery-electric vehicles tend to a higher energy density but a BEV battery of this size typically can't handle this power output.

Something seems fishy, but maybe I should dig out actual measurements of the space.
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