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Riley Elf / Classic Mini EV Conversion

4863 Views 16 Replies 7 Participants Last post by  boatman
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Hi Everyone,

I planning an EV conversion for a Riley Elf but as far as I can tell this setup would work on any classic mini.

I am very early in the planning stage and I don't currently even have a car yet.

The forum has been a good start for learning what goes into an EV conversion but I am by no means an expert in fact I'm clearly a novice.

I have been trying to space out and plan the build using AutoCAD by using scaled 2D drawings I have found for the Elf, subframes, motor and shell. This clearly has its limitations and ideally I would like to get my hands on a scanned mini shell.

I am planning on using the SWIND HPD E 80 motor as this is such a small unit that mounts nice and low in the engine bay. I plan on either using a modified front subframe with mounting points for a battery box above the motor or by using a subframe similar to the design of the B-TEC tubular frame conversion.

This should allow for enough space for a battery box that will hold 8x CALB modules. This may require the inner wings to either be cut back or removed to allow for the width of the box. This will also require the radiator and fan to be mounted in the front grille, vertically for the Elf or horizontally for a normal mini grille.

I chose the CALB 6P2S for their voltage as the motor is 400V and this set up gives the most voltage over the LG version or the 4P3S CALB.

There will be a further 4 or 5 modules in another battery box in the rear subframe. This will require strengthening of the rear subframe and also the boot floor panel to be cut out and a flat panel to be welded in to remove the 12V battery box and spare wheel well. Potential to use a modified mini van rear floor panel.

This means that I should have total battery energy capacity of 26.6 kWh and a nominal voltage of 266.4V.

The controller, DC/DC converter are yet to be decided. I have found the Cascadia PM100DX for an inverter but am open to other options as the costs are starting to escalate by this point. They, along with the charger will be hidden in a fake fuel tank in the boot, this will allow for all them to be located directly underneath the filler neck.

I am looking at the potential of using two Tesla gen 2 charger to give a fast charging capacity of 20 kW. I don't currently have a place to park and charge the mini so would most likely be doing street charging hence the need to be able to charge quicker.

All connections from front to rear will be via exhaust tunnel so no HV inside the cabin.

I think additional weight / balance should not be too affected as the rear weight is over the wheels and nice and low. The front battery box (96 kg) and motor (50 kg) are not much more than the presumed weight of the a series & gearbox.

So what do you guys think? Any advice about this setup would be appreciated.

Cheers,

Jon

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That all makes sense, except for the inverter location. From the fuel tank location to the motor is extremely long for inverter to motor cables. Doesn't Swindon offer a suitable inverter to go with the motor, and set up to mount with it?

It also seems unlikely that the PM100DX (200 x 87 x 314 mm, 5.5. L), a Zero EV 1 kW DC-to-DC (290 x 159 x 73 mm), and two Tesla chargers will fit in the fuel tank space, assuming that it is something like the Mini tank.

I chose the CALB 6P2S for their voltage ...
I assume that this is just a typo, and you meant 6S2P (which would make more sense and is shown in the drawings).
I wasn't aware that the inverter to motor distance was a factor...

Out of interest what is the reason for them needing to be close together?
Without looking at it in detail, I have always assumed that long cables cause problems due to cable inductance. Industrial VFD cables can be very long but they're typically running at only 60 Hz, while EV motors typically run at several hundred hertz or more at high vehicle speed. In very practical terms, shielded 3-phase cabling is more expensive than unshielded DC cabling, so it helps to keep the AC side short even if that makes the DC side longer.

The Cascadia inverter manual isn't very specific, saying only:
"The motor wires are the most likely to generate EMI and they also carry a higher average current than the DC power wires. When installed in the vehicle these wires should be kept as short as possible. It is also recommended that shielded wire be used for the motor wires."​
With regard to CALB batteries...Perhaps I'm not up to speed, but I'm almost certain you'll get better energy density and performance for less money by using an OEM battery pack out of a Leaf, Tesla, or Bolt.
CALB is well-known in this forum for their prismatic LiFePO4 cells, but probably not for their modules.
In case anyone is not aware of these specific modules, CALB is building them of 12 pouch cells in the VDA 355 format, in either 6S2P or 4S3P configurations. Either way they're 2.2 kWh in 5.8 L and 12 kg. I don't know that the chemistry is, but based on the 3.65 V/cell nominal voltage they're not LiFePO4. The energy density is better than the commonly used LG Chem 16S modules (which are used by the Chrysler Pacifica Hybrid). Of course they'll be more expensive than salvaged modules, because they're new.
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Hi Duncan, just want to say I'm not having a go at your suggestion, but that it doesn't fit my project design criteria. I have come across the beam axle when researching for this project. It's not the path I want to be going down...
As he explained, Duncan didn't suggest a beam axle at all, only changing the subframe. Much of the Mini rear subframe (grey in this photo) is there to accommodate the stock rubber or hydrolastic suspension units, and to distribute the load along the vehicle structure:


If you change to vertical spring/shock units (coils on telescopic dampers/shock absorbers), you can replace the big subframe with something simpler just across the front of the space, but the vertical load will be concentrated at wherever you mount the tops of the shocks:

In the above example, the stock trailing arms are replaced, but the replacements are still simple trailing arms (connected by a stabilizer bar).
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Zero EV get around 100 miles out of their 26kW pack in their MX5 so I should get around 120 miles in the lighter mini with 22kW.
I think that's very optimistic. Even if it is lighter, the Mini will have higher aerodynamic drag. The 260 Wh/mile value for Zero EV's MX5 might be plausible (although it is better than many production EVs using state-of-the-art technology and developed in billion-dollar programs), but to expect to use only 183 Wh/mile (a 30% reduction) is likely unrealistic.
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