[24Seven]

Hi, I know this is an old thread, but was just wondering if you got anywhere with the coupe? I am really keen to convert one, but am just at initial planning stages
Regards, Matt

Hi Matt,

This project is still active, but progress is slow. Since last time I posted here I've done alot more research, spoken with SFRO (the local inspection/registration agency for altered vehicles), built an electric Cafe racer motorbike and cleaned the garage

As of now my recipe looks like this:

• Tesla front motor
• Aftermarket control board for Tesla inverter
• 350-400V, 20-30kWh, 600A+ battery
• Steering column with electric servo
• Electric water pump
• Electric vacum pump for the brakes
• .....

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.

I don't really want to raise the weight of the car, hence going for low weight/short range.

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

 

[Smatt]

Hi, I know this is an old thread, but was just wondering if you got anywhere with the coupe? I am really keen to convert one, but am just at initial planning stages
Regards, Matt

Hi Matt,

This project is still active, but progress is slow. Since last time I posted here I've done alot more research, spoken with SFRO (the local inspection/registration agency for altered vehicles), built an electric Cafe racer motorbike and cleaned the garage

As of now my recipe looks like this:

• Tesla front motor
• Aftermarket control board for Tesla inverter
• 350-400V, 20-30kWh, 600A+ battery
• Steering column with electric servo
• Electric water pump
• Electric vacum pump for the brakes
• .....

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.

I don't really want to raise the weight of the car, hence going for low weight/short range.

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

Hi there,
Thanks for the update!

You have a lovely looking coupe - looks like a 'LE' - much too nice to scrap as suggested above!!
I am stalling at the moment as I am not sure the car I have in mind is in good enough condition to start on without loads of work
Once I've resolved this, I was planning on looking into Tesla front motors as some say they will not fit, but if they do, I feel they would be perfect level of performance vs the original car...

 

[24Seven]

Hi there,
Thanks for the update!

You have a lovely looking coupe - looks like a 'LE' - much too nice to scrap as suggested above!!
I am stalling at the moment as I am not sure the car I have in mind is in good enough condition to start on without loads of work
Once I've resolved this, I was planning on looking into Tesla front motors as some say they will not fit, but if they do, I feel they would be perfect level of performance vs the original car...

Thanks! yes it is an LE. It has been garage kept most of its life so it is 99% rust free. Sorry to hear about the condition of your Coupe, but it might be for the better. I am hesitant to put the angle grinder and welder to the original metal of my car, allthough this would make it much easier to get parts to fit good. In your case maby this is not an issue and you could make batteries etc. fit perfect by cutting and altering your coupe.

I have not yet meassured the engine bay but was almost certain that the Tesla front motor would just drop in, Have you heard of any specific reason to why it would not fit? Is it the centered gearcase/diff that would hit the steering pherhaps?

 

[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.

 

[24Seven]

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).

Hi Brian,

Really good feedback, and the answer is: I'm not really shure anymore...

The initial reson for choosing the front motor was to have better clearence for the steering rack keeping the drive shafts level. I have relized now though that this might not be necessery as my car is lowered about 40mm and the drive shafts are pointing slightly upwards as it sits.

The other reason for choosing the front drive unit was that I liked the OEM mounts better on that one compared to the small rear motor.

I will need to mount some of the batteries in the engine bay so It would be nice with a lower drive unit to keep the CG as low as possible in the car.

Rear drive unit is looking better and better, just need to get the ICE motor out and take some meassurements.


Thank's!

 

[24Seven]

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.

Again, excellent suggestions Brian, thank's!

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

Regards
Martin

 

[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.

 

[dtbaker]

Looking at recent threads in the forum, it looks like everybody is stuck on using OEM AC motors and high voltage OEM battery packs. This seems to be a bit much for the typical DIY-er as you have to cobble together many cells that may not be matched, and hack your way into a complex BMS to manage the charge and balancing.

What has happened to the simple, less expensive, but really fun 'performance build' with something like:
Warp9 DC motor
Zilla 1000amp controller
144v or 156v pack of 130, 160, or 200ah CALB LiFePO4 cells?

 

[MattsAwesomeStuff]

What has happened to the simple, less expensive, but really fun 'performance build' with something like:
Warp9 DC motor
Zilla 1000amp controller
144v or 156v pack of 130, 160, or 200ah CALB LiFePO4 cells?

Warp9 - https://www.go-ev.com/End_User_Pricing.html , $2400. Versus a forklift motor for $200 and the same performance.

Zilla 1000amp controller - https://www.evwest.com/catalog/prod...ucts_id=419&osCsid=5uom2bcrt4im12b7ti33s4h8i4 , $2600. Versus, many DIY options.

144v pack of CALB LifePO4 cells - https://www.evwest.com/catalog/prod...ucts_id=211&osCsid=5uom2bcrt4im12b7ti33s4h8i4 - 40 x $259 = $10,000. And they are famously bad, and suck, and still need a BMS as much as any other DIY options does.

Conversion cost for those 3 components: $15,000.

...

Why aren't people doing things that way?

... Because you can buy a used Nissan Leaf for $5,000, that comes with motor, controller, transaxle, and batteries.

... Because you can spend $200 on a junkyard motor, $1000 on a P&S controller, and $2000 on Volt batteries and get more power and range for $3200 than your suggestion for $15,000?

... Because you can buy a Prius transaxle and controller for $500, and it's looking like you can get 500hp out of the controller, from Damien's Prius hack board?

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

 

[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.

 

[dtbaker]

Warp9 - https://www.go-ev.com/End_User_Pricing.html , $2400. Versus a forklift motor for $200 and the same performance.

Zilla 1000amp controller - https://www.evwest.com/catalog/prod...ucts_id=419&osCsid=5uom2bcrt4im12b7ti33s4h8i4 , $2600. Versus, many DIY options.

144v pack of CALB LifePO4 cells - https://www.evwest.com/catalog/prod...ucts_id=211&osCsid=5uom2bcrt4im12b7ti33s4h8i4 - 40 x $259 = $10,000. And they are famously bad, and suck, and still need a BMS as much as any other DIY options does.

Conversion cost for those 3 components: $15,000.

...

Why aren't people doing things that way?

... Because you can buy a used Nissan Leaf for $5,000, that comes with motor, controller, transaxle, and batteries.

... Because you can spend $200 on a junkyard motor, $1000 on a P&S controller, and $2000 on Volt batteries and get more power and range for $3200 than your suggestion for $15,000?

... Because you can buy a Prius transaxle and controller for $500, and it's looking like you can get 500hp out of the controller, from Damien's Prius hack board?

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

hhhmmmmm,
well, I've noticed a number of COMPLETE conversions come up, just lacking batteries for a song. And, I'm still pretty convinced that with 38-48 cells you really don't need a BMS at all if you are willing to top-balance and re-balance manually every 6 months.

each to their own.

I just love to see experimentation and people getting it DONE with DIY rather than paralysis by analysis. I guess its the rat-rod DIY keep-it-simple approach in me....

 

[MattsAwesomeStuff]

And, I'm still pretty convinced that with 38-48 cells you really don't need a BMS at all if you are willing to top-balance and re-balance manually every 6 months.

I'm kinda with you there. Though, having some ability to check is important.

However, that's not a unique argument for LiFe batteries.

I presume you're saying that 38-48 cells doesn't need a BMS, but the typical 96 cells in an OEM EV does?

It's linearly, 2-3x the risk. Not that much, not an order of magnitude. And, considering the failure rate of CALB or other LiFe cells (almost always) versus OEM cells (almost never?), I think the balance actually goes the other direction.

I just love to see experimentation and people getting it DONE with DIY rather than paralysis by analysis. I guess its the rat-rod DIY keep-it-simple approach in me....

That's where I don't follow you...

If you want to spend less, and have a simpler approach, then buying a Warp9, Zilla, and CALB cells is the opposite direction I'd expect you to take. I would've figured spending 20% as much and getting a forklift motor, P&S controller, and bulletproof, idiot-proof, Chevy Volt cells would've been your way to go.

Sure there's lots of project stuck deep into gutting OEM vehicles and trying to keep all the subsystems and brains, but, I dunno that there's any more there than on cheap DC projects that people abandon or sell because they're not as useful or desireable for whatever reasons.

 

[dtbaker]

I'm kinda with you there. Though, having some ability to check is important.

thats the basis of my (current) preference for fewer large format cells.... less to check. fewer connections to go wrong, and no time or expense trying to hack into a Volt, Leaf, or Tesla BMS to set parameters to a 'partial pack' at 120-160v for a DC motor.

The second issue is that the wiring in most of the OEM battery packs is designed to handle twice the voltage, but half the current I'd expect to pull with a DC motor. Pulling 1000amps out of a pack with multiple series and parallel connections designed for 500amps seems risky.

I presume you're saying that 38-48 cells doesn't need a BMS, but the typical 96 cells in an OEM EV does?

I'm saying it's just easier to 'get by' without a BMS when you have fewer cells to check. When I built my eSwift, and eMiata, there were no OEM packs available and the BMS systems were either unreliable and/or very expensive.


I haven't kept up in this forum for a while.... and wanted to ask if there is a new 'cookbook' with the kinks worked out to effectively use OEM packs for DC voltages.

What I am seeing in the build threads I'd scanned thru is that if a person wants to use OEM packs, it is probably best to stick with the factory AC motor, charger, BMS transplanting the WHOLE thing to your project whatever that may be. Leading me to the conclusion that for projects with DC motors, it's still best to use the large format cells for simplicity sake.

 

[MattsAwesomeStuff]

I'm saying it's just easier to 'get by' without a BMS when you have fewer cells to check.

Makes sense, but, your safety margin isn't that big. Like, if not having a BMS is 'dangerous', you're only avoiding said danger by 50% by using a pack with half as many cells.

And, with how unreliable LiFe batteries are (IIRC you've had multiple failures, not your fault), versus the nearly perfect track record of OEM packs, I think it more than makes up for it.

I haven't kept up in this forum for a while.... and wanted to ask if there is a new 'cookbook' with the kinks worked out to effectively use OEM packs for DC voltages.

Basically, forklift motor + OEM packs. I can't recall the last time someone actually bought a Warp9 or whatnot. If you're going DC, you might as well go cheap.

What I am seeing in the build threads I'd scanned thru is that if a person wants to use OEM packs, it is probably best to stick with the factory AC motor, charger, BMS transplanting the WHOLE thing to your project whatever that may be. Leading me to the conclusion that for projects with DC motors, it's still best to use the large format cells for simplicity sake.

I'd say there's still just as much interest in DC builds, but, not a lot of people getting them finished. Maybe the people buying whole cars are a little more committed to their projects.

Large format cells aren't "simpler" than OEM cells I wouldn't say.

You can compartmentalize most OEM packs into smaller sizes if you want.

The Nissan Leaf cells for example are about the size of a hardcover book, and just stack together like LEGO (in pairs, 7.4v per book). Tesla packs area bit trickier, but you can easily cut each module chunk in half. If you want lower voltage, you can use fewer of them.

Also, if you want lower voltage because you think it's less risky to run without a BMS, then you can just parallel up an OEM pack cut in a half rather than using it fully in series.

But most battery packs come with the BMS onboard and it's not much extra work to use it, it seems.

OEM packs are *tempting* to use the extra features that are easily available, but if you want to dumb it down for simplicity, I don't see why you couldn't be back in the same boat as using CALBs if that was your thing. And they're 20% the cost. That's a big, big deal.

 

[24Seven]

So the car is now on jack stands and I have started the process of removing the Engine/gearbox/Intercooler..... It is really squeezed in there and will unfortunately not be easy to remove.

Also found a Kia Soul EV battery locally, so that part is finally solved.

 

[24Seven]

Tried documenting the Project:

https://www.youtube.com/watch?v=kQ2qaf_isfs

 

[Smatt]

Tried documenting the Project:

https://www.youtube.com/watch?v=kQ2qaf_isfs

Nice one !

 

[24Seven]

Nice one !

Thank's!

 

[24Seven]

Here is part two:
https://www.youtube.com/watch?v=k8TKckYPrPg