[brian_]

With this simple drivetrain I might even consider converting to RWD at the same time

It would be a lot easier and perhaps cheaper to scrap the Fiat Coupé (assuming that you mean the 1990's Type 175) and start with something that has rear wheel drive... although the Coupé does have an interesting style.

 

[brian_]

• Tesla front motor
• .....

Why the front motor, rather than the small rear motor? Does it provide better clearance for the tires when steering, or is the motor intended to sit over the steering rack? The small front and rear units have the same motor and gearing, but are just packaged differently, and the rear unit places the motor lower (handy for lower centre of mass and more room above it).

 

[brian_]

• ...
• 350-400V, 20-30kWh, 600A+ battery
• .....

Most of the components are relatively easy to get hold of here in Sweden, apart from the battery. The Kia Soul EV battery would be a good match, but seems really hard to find.

...

Would really appreciate suggestions on other batteries that might be a good fit for what I'm doing.

Most current EVs have a much larger battery, and cannot be readily configured to half size while maintaining voltage. Plug-in hybrids generally have half of that battery capacity and it is awkward to combine two of them while maintaining the same pack voltage.

The other obvious battery of the desired size is from the Nissan Leaf.

There are other current or recent EVs which are adapted from gas engine models, and have battery capacity at about the target:

• Volkswagen eGolf
• Ford Focus Electric
• Fiat 500e
• Chevrolet Spark EV (on the small side; came in two entirely different types in the same package size)

What is available locally depends more on the manufacturer's marketing strategy than any technical factor.

If you really like Tesla bits, you could also risk internally converting Model S/X modules to 12S (from the stock 6S configuration) and using six or seven of them in series for roughly the desired combination of pack voltage and capacity.

 

[brian_]

I have tried doing some quick research but it is often hard to find battery specs on newer cars.

Almost all current and recent production EVs use a 96S pack, so they nominally run 360 V with almost 400 V peak (which is why fast DC chargers are designed to deliver up to 400 V).

If the e-Golf or Focus has voltage and amps the might be good donor candidates as they are available in our market.

The problem is usually that the smaller battery packs don't deliver enough of a punch (amps), although they might have close to optimal voltage. That seems to be the case for the Leaf, and might also be true for the Tesla modules if you make them 12S.

Ideally I would like to be able to make around 200kW peak, that would mean 500A @400V.

All of these similar basic EVs have roughly the same motor power, so their battery packs must be able to deliver about the same power, so with the same voltage they must be capable of about the same current.

You're looking for roughly double the power output of these cars in stock production form, so you have some options:

1. use a bigger battery,
2. use a battery optimized for power rather than energy (such as from a plug-in hybrid, but then you would need two of them for enough energy capacity), or
3. just keep peak demand short in duration, counting on the cells withstanding the discharge rate at the expense of reduced life, and assuming that you change any protective device limiting current to a level which is too low.

From what I've found tesla modules are rated at about 750A peak, which I guess would be divided in two when changing to a 12S configuration? If not this would be the perfect solution.

Right - double the voltage and half the current. You can think of this as

• the series or parallel configuration doesn't change the power capacity, so the voltage and current must change in inverse proportion, or
• twice as many cells in series means half as many in parallel, and half as many of the same cells means half as much current capability.

There is no magic in batteries, even if you fall for the cult of Elon Musk. Two EV modules of the same mass will have similar capabilities. They improve with time, of course, and there is a power density versus energy density trade-off to some extent.

 

[brian_]

I honestly haven't even heard of anyone using LiFe batteries on an active project, other than for repair/replacement in years.

Although LiFePO4 (LFP) chemistry was available in various formats and used in many applications including a wide variety of EVs, I think it has now been basically relegated to recreational vehicle house batteries (usually packaged with BMS as drop-in replacements for common "12 V" deep-cycle batteries). They work reasonably well in an RV, in part because the voltage range of a 4S configuration is moderately compatible with systems intended for nominally 12 V lead-acid batteries.

When I first joined this forum, a couple of years ago, CALB cells were still a current solution, but the transition to salvaged EV modules was underway.

 

[brian_]

There does not seem to be enough room to mount the Tesla front drive unit at the same angle as it is mounted originally.

Would it be ok to tilt the drive unit forward without creating lubrication or cooling issues?

There is an oil pickup in the bottom of the gear case; if you rotate the unit significantly you would need to relocate that so it still picks up properly.

 

[brian_]

I guess turning the drive unit 180 degrees and drive the motor in reverse direction is not a good idea either?

It can be done, by replacing the internal oil pump with one that still pumps properly when the motor is turning the other way. Zero EV has a reverse rotation pump for the large drive unit, and apparently this works okay even though the gears will be slinging oil the opposite directions to normal; I don't know if anyone has a solution for the small drive units.

 

[brian_]

I guess turning the drive unit 180 degrees and drive the motor in reverse direction is not a good idea either?

If you're still seriously considering turning the drive unit around, an alternative to reversing the oil pump in a Tesla Model S/X unit might be to use the drive units which Tesla supplied for the Mercedes B250e or Toyota RAV4 EV, which place the motor ahead of the axle line in front-wheel-drive vehicles. You would need to check for compatibility with whatever you are planning to use for controller replacement or modification.