[reiderM]

Do we need a separate controller?

For the motor/inverter (both are packaged as a single unit), yes. As brian said, there's the external CAN option. Or you can replace the logic board inside of it. There's loads of choices out there at a variety of price points to control a Tesla drive unit.

For the battery, you of course should have a BMS. Tesla modules pair nice with the SimpBMS (which I conveniently sell! lol)

I didn't get the impression that high power is required. Carrying more motor than needed and more battery than needed is a weight and therefore efficiency issue.

Batteries are certainly a case of diminishing returns as you add more, since it's also added weight. But batteries will store more energy than is needed to negate the added weight, so more is better from purely that perspective. If money and space is not a concern, of course. But yes, in terms of miles/kWh, you will definitely lose efficiency by adding more batteries. Keep in mind that more batteries will increase charging time, assuming that charge rate is held constant.

 

[brian_]

Keep in mind that more batteries will increase charging time, assuming that charge rate is held constant.

On the other hand, a larger battery will accept a greater rate of charge, so if the constraint is how quickly you can get a fixed amount of energy into the battery (rather than how fast a battery can be fully charged), a bigger battery is better. For example, a 100 kWh battery could charge at 50 kW for an hour (from 25% to 75% charged), while a 50 kWh battery would not be able to sustain 50 kW all the way from 0% charged to 100% charged.

As with everything else in life, and especially technical design, it's a compromise.

 

[Electric Land Cruiser]

The OP is talking about going fast, over 100 MPH at least (he says "sub-120 MPH). All things being equal at 100 MPH the car will be using 4 times the power as it will be at 50 MPH because of the inverse-square law.

He's going to need literally as many batteries as possible.

 

[remy_martian]

I'm at a complete loss as to why he's building a car when electric cars exist. He hasn't picked a car out yet, he never stated any rules for this "rally", so pick out an electric, mod it, put a roll cage in it and done.

 

[Toretto]

Yes!
It's this kind of specific info we need. Exactly what type of controller to use the Tesla unit and Which bms etc. We need to make a build list to calculatie cost.
But for the moment we are a bit lost, even after binge-reading.

The goal of this build is crossing countries. When Stated sub 120mph, I meant to say we're not building this car to compete with the speeds tesla's are capable of. Sustained 80 - 90 mph is probably more the goal.
The real race (when driven along with ICE Cars) is limiting stopped charging time. So that's our goal along with creating a more Aerodynamic car than any Tesla.
So we'll start with a small frontal area.

Since we want publicity and awareness, we need a theme that will stick internationally with locals.
So true to name (Toretto foundation) we are running a '94 Honda Civic coupe WITHOUT spoon engine.

Name and car is not enough, hence the conversion to electric. Now that's a complete story the people will remember when reading or hearing about it. And that's our end goal.

This is me, a petrolhead, doing what he loves and supporting a very good cause which I hold very dear.
This takes up all my spare time and there are no personal benefits. I'm asking all these questions so you can please help us help children.

This is the only way I know how to really make myself useful for this charity and raise funds.

So what we are asking is specific build details for Running either a leaf engine or a Tesla SDU.
(Will check how available and expensive Tesla's are)

500KG batteries is really stretching it, so less may be more desirable. The real race, as said, is minimizing charge time. We maximize driving time by improving aero. However this is not a hypermiling endeavour. So the throttle will be punched sometimes.

Thanks all for reading and supporting. This is a wonderfull community

 

[brian_]

The OP is talking about going fast, over 100 MPH at least (he says "sub-120 MPH).

Ah, I remember the original "fundraiser rally" description and forgot about that. Certainly up to 120 MPH (or even the sustained 80 MPH actually expected) means lots of power... and an unreasonable event. A long distance road rally is generally an open-road event, so it cannot safely or legally operate at high speed. High speed performance rallying is fast... and occurs on closed road for short distances.

All things being equal at 100 MPH the car will be using 4 times the power as it will be at 50 MPH because of the inverse-square law.

He's going to need literally as many batteries as possible.

I agree. Except that it's four times the aerodynamic drag (and therefore four times the energy used to overcome aero drag per distance travelled), and so eight times the power. Of course all drag and therefore all energy needed to move the vehicle isn't aerodynamic drag; rolling resistance and mechanical friction are roughly constant forces, so energy per unit distance for that component is roughly constant and power varies in direct proportion with speed.

The goal of this build is crossing countries. When Stated sub 120mph, I meant to say we're not building this car to compete with the speeds tesla's are capable of. Sustained 80 - 90 mph is probably more the goal.
The real race (when driven along with ICE Cars) is limiting stopped charging time. So that's our goal along with creating a more Aerodynamic car than any Tesla.
...
500KG batteries is really stretching it, so less may be more desirable. The real race, as said, is minimizing charge time.

With stops designed for cars burning fuel, 500 kg of battery will likely be too low to make it to the next stop, rather than too high.

 

[Toretto]

Thanks for your replies.
80mph is completely legal over here. So we are talking open road rallies. (It's a rally, not a race) Point to Point, choose your own route and stops.

The LEAF route seems more and more viable. The complete engines are available at reasonable prices. Both the 80kw and 110kw versions. However. To control these engines outside of a Leaf there are certain options

Now I would like to control the engine beyond 10k rpm. I suppose that the maximum kw's are still regulated by the inverter and not adaptable by either
-Thunderstruck VCU
-Resolve EV
-Johannes hubner. Openinverter
- Paul Holmes

Do any of these implement regenerative braking?
What is our best option for simplicity/ most user friendly

What options are there for a basic Dash for battery status, range, rpm etc...
Odometer would be nice

 

[TeZla]

do you have a support vehicle driving with you?

How about a trailer battery? eg, you have a leaf pack (Or tesla pack) and attach wheels and a hitch to it then power the car from that pack till its almost dead (20% SOC), then unhook it and switch over to the internal pack. the battery trailer goes onto the back of the support vehicle and when you get to a charger, you charge both at the same time. This is of course assuming that your charge stops will have 2 DC fast chargers available. There is also the ability of the support vehicle to go ahead when your close to a charge stop, to maximize its time recharging the trailer battery.
Yes, you will use a little more range (maybe a 20% range penalty?) towing a trailer as there is inherent drag to an extra axle and 500kg, but it'd have a very low profile so its aerodynamics would be quite good. the trailer could also easily incorporate passive air cooling to manage the heat of the pack.

re the motor, I think the leaf would be ideal for your build, It'll be a lot more simple to integrate into an existing vehicle rather than trying to engineer a whole new subframe for a tesla motor. You would have a potential advantage of gears in a gearbox too if you mate the motor to the stock gearbox (which then lets you use stock driveshafts etc)
It would possibly be worthwhile pulling the gearbox apart and removing any of the gears you wont be using, eg 1st, 2nd and 5th, to reduce any rolling friction in the box.

If you know your rough .cd of the car, you can roughly calculate the kw required to maintain a certain speed, perhaps you need to pick an optimal speed like 80mph, From there, you can calculate the ideal gear ratio to keep the leaf motor spinning at its optimal rpm for that speed, essentially tuning for peak efficiency. This is a tortoise and hare race, you are not the hare. slow(ish) and steady will get you over the line.

The motor/battery/inverter and SOC information can easily be displayed on a tablet reading from the CAN data, using something like TorquePro. there are quite a few solutions out there. The speedo and odometer can be easily sorted by using an aftermarket one from Speedhut. either the GPS unit as a complete independent standalone unit, or the CANBUS one for intergration into the rest of the system. For simplicity, The GPS unit is probably ideal. the downside is that they tend to drop out when you go through tunnels and can sometimes need a minute or two to locate the satellites before you drive away.

 

[MattsAwesomeStuff]

-Thunderstruck VCU
-Resolve EV
-Johannes hubner. Openinverter
- Paul Holmes

Paul Holmes' inverter, aka Paul & Sabrina, aka P&S, aka Open ReVolt is effectively defunct, and I don't even know if there's a functional open design that's been published. Scratch that one off.

Johannes' OpenInverter can do regen yes, but no one builds those anymore. The OpenInverter project has mostly moved to software, and repurposing OEM EV and hybrid inverters because you can buy a used one of those for 10-20% the cost of even just building one of his design yourself.

I have no familiarity with the other projects.

There are 2 or 3 VCU projects based on the OpenInverter project. I think there's a Leaf one maybe, a Lexus GS450H based one, and then the ZombieVerter which is designed to have modules for each respective vehicle you might have taken it from (so that the VCU part stays the same and you more or less design plugins to use it on different inverters via CAN messaging). That means you're not reinventing the VCU wheel every time you want to adapt it to a new bit of hardware. It's heavily Toyota based right now.

 

[remy_martian]

I'd go with a fast swap pack from a support vehicle that has a big diesel generator on it.

cough cough

Biodiesel fueled of course

 

[57Chevy]

- is there an efficient rev range in electric motors?

Yes, very much so. Normally a motor is designed to have a nominated rpm limit for the given supply voltage and to go faster than that you have to use field weakening which wastes energy and produces more heat in order to overcome this inherent limit in the motor. FW starts around 65MPH in a conventional ev because the majority of its life will be spent at legal speeds. I have heard a Tesla has to de-rate its motors considerably if driving excessively fast because they overheat. I have heard 50kW sort of power range after some time at high speed due to thermal limiting, although have never verified this. If you wish to run a standard EV drivetrain fast for extended periods then you will encounter this issue and your power and range will be somewhat less than you had anticipated.

Older DIY EVs use a gearbox to get around this speed limitation so that could be an option combined with a forklift style AC motor.

 

[Toretto]

Thanks all!

do you have a support vehicle driving with you?
... if you mate the motor to the stock gearbox (which then lets you use stock driveshafts etc)
It would possibly be worthwhile pulling the gearbox apart and removing any of the gears you wont be using, eg 1st, 2nd and 5th, to reduce any rolling friction in the box.

This is a tortoise and hare race, you are not the hare. slow(ish) and steady will get you over the line.

Support vehicle is possible if the swappable battery pack is an option. Trailer pack is a no-go.

I was leaning towards using the complete Leaf unit with it's 'gearbox' as a whole. And adapting the driveshafts.

It seems more straightforward than machining Parts to use the stock gearbox

I'd go with a fast swap pack from a support vehicle that has a big diesel generator on it.

Is this possible? To swap an extra pack in during a stop? Can you just implement this in the BMS ?

Is it possible to have a permanent Tesla pack, and another 4 Non-Tesla cells in the trunk which are not cooled like Leaf cells?

Because if there are 2 identical packs they can be swapped routinely and charged en route (as you suggest)

 

[Duncan]

You need the power unit (motor and reduction gear) from a modern EV
Battery pack the same -
Expect to run in the 360 - 400 volt range
Lower voltage units draw more current with higher losses

Despite Brian's comment today Tesla's have a higher efficiency than any of their competitors in terms of energy usage per mile
And because of the numbers sold they are probably the most commonly available as crashed cars

Ignore all of the aftermarket motors and batteries - they are not in the same league as the OEM ones

The Leaf power unit is pretty good - probably not as good as the Tesla but not far off
The Leaf batteries however are NOT - the fact that they are not liquid cooled rules them out for your sort of application

 

[brian_]

Despite Brian's comment today Tesla's have a higher efficiency than any of their competitors in terms of energy usage per mile

In the published claims, yes. In real-world testing, not so much. And those are complete vehicles being tested, not just motors and controllers, so the actual efficiency of the motors is unknown for most motors.

There's nothing wrong with Tesla efficiency, and it's probably better now that they have caught up with the rest of the world and use permanent magnet synchronous motors, but there's also nothing magical about it.

 

[remy_martian]

You need the power unit (motor and reduction gear) from a modern EV
Battery pack the same -
Expect to run in the 360 - 400 volt range
Lower voltage units draw more current with higher losses

Despite Brian's comment today Tesla's have a higher efficiency than any of their competitors in terms of energy usage per mile

So says Elon

Why would that be? Must be the hub caps 😂

No longer all Teslas at the top:

 

[Toretto]

... use permanent magnet synchronous motors....

Is that what the leaf motor is?

 

[remy_martian]

The Leaf has 30% worse efficiency in that chart, so why does it matter when efficiency was allegedly at the top of your list of requirements?

Make a list of priorities, stop moving the cheese with confirmation bias.

 

[Toretto]

The Leaf has 30% worse efficiency in that chart, so why does it matter when efficiency was allegedly at the top of your list of requirements?

Make a list of priorities, stop moving the cheese with confirmation bias.

Yes, as a car the leaf has 30% worse efficiency. We just need the drive unit. Not the terrible body and batteries etc...

They are available, relatively cheap, there is lots of support on this forum, and People have had very decent results with them.

The whole build has to be feasible aswell.

As far as moving the cheese, I'm learning here Remy ....

 

[57Chevy]

You might be disappointed with the Leaf motor

 

[Toretto]

You might be disappointed with the Leaf motor View attachment 127526

Yes, but there are options to Rev them beyond the Original 10.000rpm, which is what I'm after.

Results have been positive with the leaf performance, so I read