# CorVolt: 1971 Corvette's journey to electric canyon carver



## joekitch (Sep 13, 2013)

*Location: *San francisco, CA

*Budget: *hopefully less than 20k for all the conversion parts and any labor costs, but realistically this will push 25k. the car itself was 18k in the end

*Donor car: *a 1971 corvette in January from a fellow in new jersey who restored it and modified it quite a bit (crate motor and 5 speed transmission drivetrain swap, lots of suspension work, etc)

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Motor: *Tesla model S P85 large rear drive unit OR Tesla model 3 performance rear drive unit. Some strategically welded arms from the ladder frame to the motor mounts should work well. This could be relatively easy or the hardest, most expensive part of the entire project. The motor 3 motor is more efficient when not under heavy load, and FAR FAR better cooling capacity BUT nobody supports their firmware yet and it isn't clear how many years it'll be until AEM will support it, if ever. Very adventurous folks like damien macguire are only now getting the thing to spin using other open source inverters, 





as for mounting, i was thinking this, a 180 rotated around the horizontal axis, with three mounting arms welded to the ladder frame on the front, back, and side
this will require running the motor in reverse full time, i'm sure some inverter settings will allow this
it'll also require installing a special oil pump adapter by zero EV which allows oil to flow in reverse drive Tesla Large Drive Unit Replacement Reverse Rotation Oil Pump - Zero EV
i'll need to cut into the car's fiberglass body, but i don't know how much


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a very big problem is going to be the rear suspension geometry, which normally relies on a leaf spring and a sway bar system bolted to the bottom of the diff, and the half shafts actually push and pull on the diff as a suspension component, VERY BAD For a tesla motor! 
I'm looking into alternative suspension systems which use coilovers instead, like ridetech's, which is $1900 without the actual coilovers.

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but even with this i'm not sure if the half shafts are still active suspension components?
There's even more expensive systems like detroit steel's DECAlink which is over ten grand!






*Battery:* 34kw of chevy volt batteries. I'd like Gen2 but the Gen1s are half the price and only slightly lower capacity. Some in the engine bay with a battery enclosure to make it look like a V8 because yummy under hood candy, like ICON's derelict mercury EV did. the rest of the batteries go where the gas tank used to be, which may or may not hang lower and thus cause the full size spire tire sling to have to go away. Volt batteries have excellent high performance (power density) because of almost no voltage sag. They're also cheap, work very reliably, have a nice log-like form factor, and have built in excellent battery cooling. I'm hoping for 80+ miles of range. 
Something like $5000 for two Volt packs in good condition.



*Cooling:* unsure yet, but the water pump and electrically controlled diverter valve out of a tesla. chevy volt batteries and the tesla motors have built in cooling systems so no need to screw around making chill plates.
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Controller: *AEM EV VCU200 VCU200 Programmable Electric Vehicle Control Unit | AEM EV , i've heard about these for a while, and Bisi of Bisimotors used this as the basis for his electric porsche 935 project. According to him, it works extremely well and is very polished overall. My guess is all the different modules i purchase from them will add up to like, $4000











*Contactor: *unsure

*Power steering:* I really want to keep hydraulic power steering, electric pump driven. It's wasteful but it feels so much better than electric power steering. EV West makes a belt fed pump but i'll probably re-use the one that came with the car, which is a really nice Steeroids rack and pinion setup

*A/C: *MVP might omit this since i live in a SF and A/C is kinda unnecessary

*Charger: *Not sure how to get there, but i absolutely want to shoot for a level 3 fast charger which interfaces with CCS. With such a short range this feels like a heavy requirement for this to be driveable. There's some noises about CCS charging for DIY builds but this might be a wait and see, hopefully this becomes a mature thing soon (within a year).


*Safety: *Haven't researched much but i would really like switchable fuses between every 72 volts or so, so at any given moment during assembly or maintenance, if i make an oopsie, i only get shocked with 72v before a fuse cuts it. Also, inertial fuses so in a crash, everything is isolated from everything else. Also, a first responder safety line, mimicking tesla's implementation with a BRIGHT RED WIRE right under the hood with a really obvious label on it


*Styling: *a very important aspect for a classic, i'll need a wide rear track for thick tires, and some huge flares should pair nicely. I'm also a big fan of Fathom green, this really deep forest green that chevy used for only a few years. As such, the final product is going to look a lot like this, Garrett Randall track weapon project















*Timeline: *With the c3 now in my garage, i'm going to spend about a year maintaining it, adding quality of life upgrades, more deeply researching the platform, more deeply researching the feasibility of my componentry and fabrication. HOPEFULLY buy most of the drivetrain bits in advance and make sure the entire thing works on a bench, THEN start converting in spring of 2020 and be done some point before spring of 2021


*This is obviously going to evolve with time, but the way forward seems relatively clear for now, minus some wait time*

there's a companion thread over on the c3 forums
CorVolt: The 71 Restomod journey to electric - CorvetteForum - Chevrolet Corvette Forum Discussion

also there was an initial thread over there proposing the project and hashing some stuff out
Rate my build plan (c3 corvette)


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## MattsAwesomeStuff (Aug 10, 2017)

I love a well-documented project.

I'm converting the little brother to your C3, a blend of 1970 and 1972 Opel GTs. Poor man's C3 I suppose.

https://www.diyelectriccar.com/forums/showthread.php/matts-1970-opel-gt-project-log-200587.html

I went over to your thread on the Corvette forum. Yep, same BS I got on my Opel GT forum. Lots of ignorance of people who have no clue about what an EV is (some deliberate and some innocent), a handful of people condemning you for what you're doing to your own property because there are correct and incorrect opinions to have about cars apparently, and a mostly supportive group of people just happy that you're passionate for project and sharing it with the world.

Your car looks fantastic. I've been looking at GTs so much, I forgot how much I love the comparatively steroided-up look to the C3's. Looks stellar and sinister in black.

There were a pair of C3 conversations happening here in the last year, seem to have fizzled out, haven't seen updates in a long time.

A few notes...

- You're avoiding the Model 3 drivetrain. Damien's already got his spinning, he usually sinks his teeth in until he's got a success. He piggybacks on Johannes' Open Inverter software, which works pretty much universally, so, once he's reverse engineered the Model 3, it's pretty much just waiting to go. It's not that many wires. It's a 6-pole (3 paired) resolver, that was his last stumbling block, and then 3 power leads. The motors are dead simple.

You don't have to use the inverter there to drive the motor. You can use any inverter, as demonstrated by him using the Prius Gen 3. This week's news about the Prius Gen 3 inverter, Damien discovered just the MG2 inverter alone will handle 500 amps before gracefully shutting down. The Gen 2 did about 70% on the MG1 as its MG2, so, you could realistically see 850 Amps out of an inverter you can often pick up for around a hundred bucks. Just ludicrous value for engineering and hardware.

- I would not use the fancy expensive controller you're planning. I think every single Tesla controller sold is based on Johannes' Open Inverter open source project, they just print and rebrand their own boards. You don't get any support beyond using the forums to help troubleshoot, but it's like 1/10th the price.

- You're worried about suspension. Why not just grab the whole suspension from the Model S or Model 3 or whatever you're going to use, and adopt it wholesale? Only issue might be width, Teslas are fat cars, but, if you want it low with wide flares, no problemo.

Sounds like you've got this all pretty well researched. I'm guessing with you having lost your job recently that this has become a bit more of a budget build, so, maybe some of those are corners you want to cut.

I was on the fence about you whittling a coffee table into a toothpick, taking a running, modded 'Vette when there's gotta be some aborted projects around for cheaper and easier. But, I like your idea of just driving it first for a year. It'll get you nice appreciation for the old, and a good comparison to what it became.

Keep us all updated, would love to see regular updates.


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## joekitch (Sep 13, 2013)

i'd classify the opel as more like the lighter, more nimble european c3, probably a better ev candidate to be honest. It's just that i've loved the c3's design forever.
the ope GT's curb weight is 1900-2100 pounds, the c3's is over 3500!



> - You're avoiding the Model 3 drivetrain.


indeed damien's been making great progress, and that may be a possibility later on, but for now i'm researching based on the model s motor in terms of mounting, most of which will carry over to the model 3 motor if i switch to that. IT also depends on if AEM supports the model 3 motor any time soon, which is probably likely? Also the power peak of the model 3 motor is unknown, while the model s motor can make 600hp without too much fuss



> - I would not use the fancy expensive controller you're planning.


i'm doing everything possible to remove install complexity and points of failure, as well as remove "fiddly bits", AEM's controller is (according to people using the early pre-release versions) really polished and they have excellent customer support. You definitely pay for that in extra cost but this is one area where i'm ok paying extra to avoid headache



> - You're worried about suspension. Why not just grab the whole suspension from the Model S or Model 3 or whatever you're going to use


that was my original assumption but i had a talk in person with brian from ev west at fully charged live and he basically begged me not to do that. It'd actually be far more involved to graft an entire subframe onto the c3's ladder frame, not to mention after all that work you'd have a downright mediocre suspension setup with the model s (doesn't even have much adjustment), or a kinda-ok suspension setup with the model 3. He strongly recommended sticking to the very large c3 suspension aftermarket 



> I was on the fence about you whittling a coffee table into a toothpick,


i wanted to avoid doing restoration work which tends to be really time consuming and not as rewarding. And yeah i wanted to actually drive the car for a while before taking it offline for months, instead of it arriving at my door already on jackstands such that i can't enjoy it.
and again, with the one year time delay, no sense getting something that'll just rot in the air


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## MattsAwesomeStuff (Aug 10, 2017)

joekitch said:


> probably a better ev candidate to be honest. It's just that i've loved the c3's design forever.


Agreed. I'm not a car guy, but the only car I've even really had a strong opinion on, is how much I love the C3.

I'd looked at picking one up cheap for a few years, and then considered back and forth whether it was too heavy for a cheap conversion. Then I saw a GT in a car lot when I went to buy some winter tires and I was like "Wait, that's what?"

A few months later I drove to Arizona to buy 2 of them 



> i'm doing everything possible to remove install complexity and points of failure, as well as remove "fiddly bits", AEM's controller is (according to people using the early pre-release versions) really polished and they have excellent customer support. You definitely pay for that in extra cost but this is one area where i'm ok paying extra to avoid headache


Well, one thing you could do, because the cost difference is going to be so extreme, is just buy Damien's, and if it gives you a whiff of issues, go buy AEM's. It's likely only going to cost you 10% extra.

If the cheap solution was like, 70% the cost of the supported one, well, then I could see how you have to only pick one. But, since the unsupported one is so far apart, there's hardly any risk in at least trying to make it work for you.



> i wanted to avoid doing restoration work which tends to be really time consuming and not as rewarding.


I hear ya. I'm 1 year into my "summer project" last year. Without seeing a motor spin yet.


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## joekitch (Sep 13, 2013)

is the cost difference that extreme though? 

the aem VCU is $1500 for a single motor application, $1200 for a cd-7 display (new, i may find a used one for cheaper), $750 for a pdu unit for switching stuff, which i may not actually need if i keep all the stock controls for headlights and stuff and keep the entire stock 12v system....
and $300 for a usb can cable for programming....which i'll admit is rather high, i may find that used.

also i may have a way to get decent discounts on all this stuff, which changes the calculus somewhat

and damien's still be just the controller, right? i'd still have to purchase all the peripheral stuff like displays


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## 4G63T (Jan 9, 2019)

joekitch said:


> as for mounting, i was thinking this, a 180 flipped position, with three mounting arms welded to the ladder from on the front back and side
> i'll need to cut into the car's fiberglass body, but i don't know how much


Is that drive unit “upside down” ? If so, Are you sure you can just flip it and run the Large Rear Drive Unit Upside down ? My concern is there is an oil pump like devise inside to lubricate the gears. If you flip the motor will it still be able to pick up the oil and properly lubricate ? 

I think certain builds people install the drive unit orientation in such that to drive forward they run it in reverse. But to do that they install a modified oil pump or modify the existing to lubricate in reverse. 

Any one know if flipping 180* would still allow proper gear lubrication or there is a modification of some sort available to allow it ?


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## 4G63T (Jan 9, 2019)

Here is a video clip showing the oil pump. The he is installing is for running the motor in reverse.

https://m.youtube.com/watch?v=_GigD0s47RI

I wonder if there is a way to extend the pickup tube to the top , so that running the motor upside down will still work to properly lubricate ?


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## joekitch (Sep 13, 2013)

sure as heck hope it works when flipped 180 as thatls the only orientation that will work for this build. If i keep it in the normal orientation, it'll hang way too far out back
although that in itself is potentially a bonus to the model 3 motor, since it seems to run in that "motor forward, diff aft" configuration










Thing is, i cannot for the live of me find any model 3 CAD models. Whoever has motors aren't scanning them, and without cad it's very difficult to mock up sizing and positioning


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## 4G63T (Jan 9, 2019)

joekitch said:


> sure as heck hope it works when flipped 180 as thatls the only orientation that will work for this build. If i keep it in the normal orientation, it'll hang way too far out back


Well, the ac motor and inverter will work and it will drive the car forward and back . The issue is the gears getting properly lubricated. It’s designed so the pump picks up oils from the bottom. Flipping it upside down and the pick up tube is at the top of the motor. 

Looking at the video, it seems like the pump plays an important role spraying oil at key areas on the gears ? If it can’t pick up any it won’t be able to lubricate . It would be like driving a car with no transmission oil.

If it’s too large (Width) to fit in the correct orientation, perhaps maybe removing and relocating the inverter ? This way the drive unit will be around 21.5” wide instead of 35” ....But this won’t help at all about hanging too far back that you mention.

Yes, the Model 3 is oriented from factory the way you want to install.

It’s not as helpful as having a cad but I was told the model 3 rear drive unit is approximately 25X17X15 inches.


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## joekitch (Sep 13, 2013)

my problem can be best demonstrated visually

flipped around, the motor cuts right through that large crossmember in the frame. 

popping the inverter off unfortunately doesn't help in this case 

but i was hoping to upgrade the lubrication system anyway, since the stock cooling on the motor is kinda bad to begin with and thats mostly because the oil pump is gear driven based on wheel speed, instead of oil temp


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## Duncan (Dec 8, 2008)

The solution is cut the crossmember off and weld it back on in a different place


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## joekitch (Sep 13, 2013)

easier said than done, i believe that crossmember is a major part of holding the body of the car onto the frame...


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## Duncan (Dec 8, 2008)

joekitch said:


> easier said than done, i believe that crossmember is a major part of holding the body of the car onto the frame...


Then move the mountings - or add a mounting frame that meets up with the body and still misses the power unit

Chassis stuff is easy! - modern MIG welders are awesome - and you can do all of your "modeling" with a couple of dollars worth of cardboard

It's much easier to mess with what is basically an incredibly simple and crude ladder chassis than to mess with a modern and sophisticated power unit

In my world (people with different skill sets will differ) it goes

Most Difficult to least Difficult 
SOFTWARE
Electronics
Precision machined parts
Bodywork
Suspension
Chassis


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## MattsAwesomeStuff (Aug 10, 2017)

Kevin Sharpe tried to get some crowdfunding going for a 3d scan of the Model 3 motor while it was on loan at Damien's. But that mostly fizzled. Not enough people need it or are interested in it.

You'd think that EV shops would jump at that chance to pitch in, but, nope.


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## brian_ (Feb 7, 2017)

joekitch said:


> a very big problem is going to be the rear suspension geometry, which normally relies on a leaf spring and a sway bar system bolted to the bottom of the diff, and the half shafts actually push and pull on the diff as a suspension component, VERY BAD For a tesla motor!
> I'm looking into alternative suspension systems which use coilovers instead, like ridetech's, which is $1900 without the actual coilovers.
> 
> 
> ...


Yes, C3 (and C2) suspension is horrible.

The leaf spring in any generation of Corvette suspension is not part of the suspension geometry - it acts only a spring, not a locating arm. The leaf spring gets replaced by coils for a few reasons

to change spring stiffness (easy to swap in various coils, hard to get custom leaf springs made to fit the car for different rates, especially with the later fiberglass leaf springs),
coils on shocks are lighter than the steel leaf spring plus shocks, and
mounting the leaf spring can be a problem with different final drive units (which is the case with this conversion)
... but changing the geometry is not one of them.

The RideTech system shown still uses the half shaft as the primary lateral suspension links (and the small strut rods shown as the required second lateral link per side). It just has nicer trailing arms, designed to work with their coil-over-shock and mount (which they call "MuscleBar") system.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> I'm converting the little brother to your C3, a blend of 1970 and 1972 Opel GTs. Poor man's C3 I suppose.


The Opel GT has the same styling (not just by coincidence), and they both have the long-hood/short-deck form and set-back engine layout that are suitable for this style of car... but that's where the similarity ends. Structurally and in rear suspension design they are wildly different, and lead to different conversion solutions.


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## brian_ (Feb 7, 2017)

joekitch said:


> ... i had a talk in person with brian from ev west at fully charged live and he basically begged me not to do that. It'd actually be far more involved to graft an entire subframe onto the c3's ladder frame, not to mention after all that work you'd have a downright mediocre suspension setup with the model s (doesn't even have much adjustment), or a kinda-ok suspension setup with the model 3. He strongly recommended sticking to the very large c3 suspension aftermarket


It is important to recognize the difficulty of adapting a subframe to the C3's frame, and the width is a critical issue, but anyone who would describe either Model S or Model 3 rear suspensions as "mediocre" or "kinda-ok" and recommend the design which GM abandoned 40 years ago instead must be a serious old 'Vette fan. The aftermarket for C3 suspension is large mostly because the C3 suspension is so undesirable.

The Model S suspension is the integral link type used by Jaguar, BMW, and Alfa Romeo. The Model 3 suspension is the five-link type used by Mercedes, Mazda (RX-8 and NC/ND Miata), BMW, and others. Yes, everything in a Tesla is copied from one of the established auto manufacturers.


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## brian_ (Feb 7, 2017)

joekitch said:


> sure as heck hope it works when flipped 180 as thatls the only orientation that will work for this build. If i keep it in the normal orientation, it'll hang way too far out back
> although that in itself is potentially a bonus to the model 3 motor, since it seems to run in that "motor forward, diff aft" configuration...


Yes, the Model 3 (and now Model Y) rear drive unit is the only current Tesla drive unit which places the motor ahead of the axle line.


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## joekitch (Sep 13, 2013)

brian_ said:


> anyone who would describe either Model S or Model 3 rear suspensions as "mediocre" or "kinda-ok" and recommend the design which GM abandoned 40 years ago instead must be a serious old 'Vette fan. The aftermarket for C3 suspension is large mostly because the C3 suspension is so undesirable..


big emphasis on aftermarket suspension, since yeah the stock isn't good

i believe his perspective is from autocross or road racing, and that it (tesla's) is heavy luxury car suspension and not sharp sportscar suspension
he's also done a lot of conversions at this point, classic and modern, so i'm trusting his take


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## MattsAwesomeStuff (Aug 10, 2017)

brian_ said:


> The Opel GT has the same styling (not just by coincidence)


*nod*.

They were both born out of the 1965 Mako Shark II concept, like a common ancestor.










I love how sinister it looks. Even the C3 is friendlier and more subdued.



> but that's where the similarity ends. Structurally and in rear suspension design they are wildly different, and lead to different conversion solutions.


At the time, even GM's own brands weren't even really sharing notes among themselves. Let alone GM's awkward European cousin.

The C3 is a body-on-frame, the GT isn't even just a unibody - it's a monocoque, there's no frame anywhere.

They're a tiny bit the same, absurd transverse leaf springs, C3 in the back. GT in the front. The front!

Look at this goofy hillbilly front suspension with leaf springs on a 2000lb sportscar:










I want to replace it with something more modern (from a junkyard), but I wouldn't know where to start. But I'll leave such complaints in my own thread.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> The C3 is a body-on-frame, the GT isn't even just a unibody - it's a monocoque, there's no frame anywhere.


That's what "unibody" means: unitized (instead of separate) body and structure. A Corvette is not unibody because it has a composite body and GM wasn't (and still isn't, with the eighth generation) crazy enough to use a composite structure.

While more recent Corvette structures have a modern design, and the C3 (which is essentially unchanged from the C2) is a perimeter (not ladder) frame, the rail spacing and height through the rear suspension area are unlikely to match the mounting point of another random vehicle's subframe, and that's a challenge for integrating any complete subframe designed to mount to specifically located unibody structural points.

There are a few vehicle platforms which have body-on-frame construction and are available in one model with a beam axle and in another model with independent rear suspension (Ford F-150 & Expedition, Toyota Tundra & Sequoia, Nissan Frontier & Pathfinder, etc), and in each case the rear frame section is different to accommodate the different suspensions. This is the sort of conversion which doesn't just "bolt in with a couple of brackets".


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## brian_ (Feb 7, 2017)

joekitch said:


> big emphasis on aftermarket suspension, since yeah the stock isn't good
> 
> i believe his perspective is from autocross or road racing, and that it (tesla's) is heavy luxury car suspension and not sharp sportscar suspension
> he's also done a lot of conversions at this point, classic and modern, so i'm trusting his take


Any difference in "sharpness" would be the effect of bushing compliance, and the bushings which seem soft for a Tesla would seem quite a bit stiffer for a much lighter car.

And are you saying that the guy at EV West has done "a lot" of conversions of Corvettes (or even anything else) to other suspension systems, specfically from Tesla? I doubt that's true.

Regardless of the desirability (or lack thereof) of a Tesla suspension in a C3, the practical approach may be to minimize changes, by

replacing the location function of the axle shafts with a pair of lateral locating arms mounted at or above the axle height, while using custom half shaft with CV joints that allow plunge travel, and
only if necessary for drive unit mounting, replace the leaf spring with a coilover conversion kit

C3 leaf spring to coil conversions usually involve goofy rocker systems (as in the Shark Bite) or extended trailing arms (as in the RideTech system) to keep the coils from interfering with the half shafts, so they're not trivial.


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> They're a tiny bit the same, absurd transverse leaf springs, C3 in the back. GT in the front. The front!
> 
> Look at this goofy hillbilly front suspension with leaf springs on a 2000lb sportscar...
> 
> I want to replace it with something more modern (from a junkyard), but I wouldn't know where to start. But I'll leave such complaints in my own thread.


Yes, they share that, and the Corvette used front leaf springs as well, starting with the C4.

I don't know why this would be considered absurd, goofy, hillbilly-style, or not modern. The suspension arms and geometry are the same as they would be with coils, and the leaf springs are very compact; in fiberglass (as they are in the later Corvettes) they're even light. GM only moved away from the leaf springs for the latest generation (C8), probably mostly for packaging (sometimes there's something where the spring would need to run) and because so many buyers want to change springs and that's easier with coils.

In this C3 conversion the only reasons to change from the stock rear leaf spring would be:

as part of a larger change in suspension type to avoid the use of half shafts as suspension links, or
because the leaf spring or its mount interfere with the Tesla drive unit housing and mounting.


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## joekitch (Sep 13, 2013)

brian_ said:


> In this C3 conversion the only reasons to change from the stock rear leaf spring would be:
> 
> as part of a larger change in suspension type to avoid the use of half shafts as suspension links, or
> because the leaf spring or its mount interfere with the Tesla drive unit housing and mounting.


both of these are true for this build.
also, coilover adjustability will be very useful when dialing the car post-conversion


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## 4G63T (Jan 9, 2019)

I just thought of something that might work if anyone with better knowledge or experience can comment / confirm.

Instead of flipping the drive unit upside down 180* , how about turning is laterally ? Now doing this would spin the wheels in the opposite direction intended . To over come this , can’t we just separate the inverter to run externally away from the drive unit and then reroute the 3 electrical wires in a way that it would spin the tires the opposite direction forward ? Off course you will need to get a modified oil pump that would work with the motor spinning in reverse.

I think this will be much easier than to flip it upside down and run external pump etc.. Also this is assuming your using a controller that won’t support running the drive unit in reverse with intention and same power output/speed as forward.


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## joekitch (Sep 13, 2013)

from what i understand, the aversion to running it in reverse is the same problem, that when in reverse the oil pickup and spraying system doesn't work, so the gears get no lubrication. That is a good potential move though, and i doubt that requires relocating the inverter either.

Just heard back from bream of ev west, apparently eliminating the half shaft pressure problem is as simple as switching to CV joints for the half shafts, which is actually pretty easy by using something like this, a modified trailing arm which takes C7 hubs and thus is CV joint converted
https://www.ridetech.com/product/offset-trailing-arms-with-c7-hubs-for-1963-1979-corvette/


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## 4G63T (Jan 9, 2019)

joekitch said:


> from what i understand, the aversion to running it in reverse is the same problem, that when in reverse the oil pickup and spraying system doesn't work, so the gears get no lubrication. That is a good potential move though, and i doubt that requires relocating the inverter either.


There is a solution to the oil pump to spray in reverse.

https://zero-ev.co.uk/product/tesla-large-drive-unit-replacement-reverse-drive-oil-pump/

^ that is a replacement reverse pump that ZeroEV sells.


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## brian_ (Feb 7, 2017)

4G63T said:


> Instead of flipping the drive unit upside down 180* , how about turning is laterally ? Now doing this would spin the wheels in the opposite direction intended .
> ...
> Off course you will need to get a modified oil pump that would work with the motor spinning in reverse.
> 
> I think this will be much easier than to flip it upside down and run external pump etc..


Yes, you can rotate it about the vertical axis (instead of the lateral axis), so that the same side is up but front and back and swapped. That's the usual way to place a Model S drive unit in the ahead-of-axle position.
The reverse-rotation pump - still internal and gear-driven, and available from Zero EV - which 4G63T mentioned is the lubrication solution.



4G63T said:


> Now doing this would spin the wheels in the opposite direction intended . To over come this , can’t we just separate the inverter to run externally away from the drive unit and then reroute the 3 electrical wires in a way that it would spin the tires the opposite direction forward ?
> ... Also this is assuming your using a controller that won’t support running the drive unit in reverse with intention and same power output/speed as forward.


You don't need to change the inverter to motor wiring; you just tell the drive unit to go in reverse. I haven't heard of any power or speed limit in reverse, but maybe it's just that people are also replacing the controller board.


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## joekitch (Sep 13, 2013)

4G63T said:


> There is a solution to the oil pump to spray in reverse.
> 
> https://zero-ev.co.uk/product/tesla-large-drive-unit-replacement-reverse-drive-oil-pump/
> 
> ^ that is a replacement reverse pump that ZeroEV sells.


oh, kick ass, thanks for the link, that may just be the solution i need
and i suspect aem's vcu would be totally ok with doing a reverse run setup


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## 4G63T (Jan 9, 2019)

brian_ said:


> 4G63T said:
> 
> 
> > Now doing this would spin the wheels in the opposite direction intended . To over come this , can’t we just separate the inverter to run externally away from the drive unit and then reroute the 3 electrical wires in a way that it would spin the tires the opposite direction forward ?
> ...


Not to “thread jack”, but lets say we can’t set the controller/inverter to run in reverse because we plan to have dual motor awd setup and front will need to run forward . From quick online search seems like we can switch the wiring and have the inverter signal to spin forward but the motor will spin reverse.

Only possible issue i can think of is there is an “encoder” sensor in the motor that gives the inverter position of the motor rotor. How will that effect things ? Does it care which direction it’s spinning or does it just see it did move ? Looking at the encoder gear “thing” connecting to the rotor, maybe it doesn’t care about the rotation direction ? Seems like it works similar to how ABS wheel sensor works. The cv has “teeth” that pass the sensor to sense it’s moving or stopped etc...

What you guys think?


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## joekitch (Sep 13, 2013)

word from bream is they generally avoid running the motor in orientations other than its original, so relocating the crossmember may be the best bet? 

i took a look under the car at said crossmember and turns out it is not actually a body supporting member, its basically only there to hold up the diff mount (labeled as "rear end crossmember" in this image). 










So i can remove it and possibly replace it with some steel tubing instead, but i'll still need to come up with a way to mount that lower control arm/strut arm, mounting something ONTO the motor may need to be a thing.....

like getting longer motor casing bolts and making some bracket which uses those to "sling under" the motor casing 

there's also the problem of the battery box i was planning to do, which was going to sit where the gas tank used to be, that big open area in the back between the "frame crossmember over axel and "rear crossmember" sit int he above image

man, all this is making me look at the model 3 motor again...it's far smaller, more efficient, and is designed to run in that reversed orientation. 
If it's feasible to push that thing to 500whp, i'd be happy with that


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## 4G63T (Jan 9, 2019)

^ I think your referring to Michael Bream from EVwest . 

Why not install the battery box in the front under the hood ? It will help offset the weight so your not rear heavy to the extreme.


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## MattsAwesomeStuff (Aug 10, 2017)

joekitch said:


> i took a look under the car at said crossmember and turns out it is not actually a body supporting member, its basically only there to hold up the diff mount (labeled as "rear end crossmember" in this image).



Umm...

I'm not good with cars, but...

I see the "Rear End Crossmember" bolts directly to the "Frame Crossmember Over Axle", which seems to me to be a real supporting member.

So if it's in the way, it's not a matter of just moving the thing that holds up the diff. You have to move the thing that holds up the thing that holds up the diff.


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## joekitch (Sep 13, 2013)

it supports the diff, but with this tesla motor install, the motor BECOMES the diff, so what's important is the presence of a crossmember, not its exact positioning.

so instead of one big crossmember, i can switch to two or three smaller tube ones spaces such that the motor can sit there


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## brian_ (Feb 7, 2017)

About encoders...
The Model S/X motor is an induction motor, so it doesn't need (and presumably doesn't have) a position encoder. The controller does need to know the motor speed and direction; that can be done by analyzing feedback from the motor, but I think that Tesla uses a sensor. I don't recall any wiring details for it.


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## brian_ (Feb 7, 2017)

The engine space should certainly be used for the main battery pack, and for some battery even if there's a front drive unit up there. The fuel tank and spare tire space is a reasonable place for an additional pack.


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## joekitch (Sep 13, 2013)

yes that was my plan, split the pack between the engine bay and the gas tank to even out the weight distribution as well as maximize battery space, since the volt batteries aren't very energy dense

as for all the electronics like contractors and dc/dc converter and charging and BMS, that can also probably fit in the engine bay probably? i'd prefer all that to be accessible, and the tank area is just a battery box


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## BruceL (Mar 15, 2020)

Can you cut the crossmember and then weld it back on with a center section bent around the drive unit?
I have a removable crossmember in my C2 (Richmond 5 speed road race trans is bigger than the Muncie so there's no way to change clutch without pulling the motor w/o a removable x-member).


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## Bry5on (Mar 14, 2016)

Come by my place in Berkeley some time. My ‘70 jag had the same rear suspension limitation but I went a different (less powerful) direction instead of going full custom in the rear. It’s my DD these days and I can probably help you through some hurdles before you hit them 🙂

https://www.jaguarforums.com/forum/www.jaguarforums.com/forum/showthread.php?t=184994

Looks like fun!


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## CantDecide (Oct 20, 2019)

joekitch said:


> sure as heck hope it works when flipped 180 as thatls the only orientation that will work for this build. If i keep it in the normal orientation, it'll hang way too far out back


I emailed 057 about running a Tesla motor either backwards, or upside down and backwards just yesterday and here is what they said:

> The Drive Units are not designed to work in that configuration. The oil pumps will not handle it and we do not recommend doing this with the Drive Units.

That's a bit ambiguous to me, so I asked for clarification on if just backwards but right side up is ok. I know some cars have been built this way but I don't know if the oil pump was modified. Also, it seems 057 is pretty conservative (they dis-recommend installing the Quaiffe LSD as well), so ymmv.

I'm curious about this issue as well as it could affect my build. The other option is splitting the motor and inverter and running it through a gear reduced and traditional transmission, but that seems overkill.


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## joekitch (Sep 13, 2013)

Bry5on said:


> Come by my place in Berkeley some time. My ‘70 jag had the same rear suspension limitation but I went a different (less powerful) direction instead of going full custom in the rear.


an old brown jag is a classy project basis, and going a lower power route makes sense for a cruiser

but my build is to prove a point to the old muscle car community that the future ain't all bad, and part of that means having proper muscle, meaning tons of torque and lots of tire smoke, the only real way to do that right now is tesla drive units.

also it won't really be full custom, but having seen some builds, my definition of "full custom" may be much more extreme than yours




> That's a bit ambiguous to me, so I asked for clarification on if just backwards but right side up is ok. I know some cars have been built this way but I don't know if the oil pump was modified. Also, it seems 057 is pretty conservative (they dis-recommend installing the Quaiffe LSD as well), so ymmv.


i'm not sure who/what 057 is but...
the reverse oil pump from zero EV should solve for the lubrication problem, and running the motor backwards in terms of inverter/electronics is inverting a few values, honestly.


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## Duncan (Dec 8, 2008)

joekitch said:


> but my build is to prove a point to the old muscle car community that the future ain't all bad, and part of that means having proper muscle, meaning tons of torque and lots of tire smoke, the only real way to do that right now is tesla drive units.
> 
> .


I'm part of our local "Muscle Car" community

But NONE of the Muscle cars can beat my "Device"

And that's just DC forklift power!

There were five Corvettes in my class this February - one of them was supercharged
NO COMPETITION!!

Erik's seven litre supercharged T Bucket with drag slicks did beat me !
But wait until next year


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## Greengearhead (Apr 21, 2015)

I also considered an ev conversion on my c3. I had a beautiful black 77. Changed it from auto to manual, added holley sniper injection and spark control. I posted on here and got good advice about rear suspension set ups. In the end I sold the vette and moved on ( sold it about a month ago). 
I actually live in SF too. Let me know if you need help on this cool project. I was a professional mechanic for a while at SF Toyota.
To satisfy my ev conversion itch I lowered my beater volt (not at all a conversion but it was a quick job)


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## CantDecide (Oct 20, 2019)

joekitch said:


> i'm not sure who/what 057 is but...
> the reverse oil pump from zero EV should solve for the lubrication problem, and running the motor backwards in terms of inverter/electronics is inverting a few values, honestly.


057 is where I sourced my Model S: https://057tech.com/products/driveunits

I got a clarification from them:



> The oil pumps do not operate when the drive unit is run in reverse, so changing the configuration and running in reverse would not get oil flow to the gears. That is why speed is limited in reverse.


Which I think agrees with your idea to use the Zero EV reverse pump. I didn't know that was an option. I think 057 seems to be reluctant to deviate too far from the Tesla specs, but it seems reasonable to make some of these modifications.


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## joekitch (Sep 13, 2013)

oooh yeah i forgot about those folks!
not wanting to even put in a quaife LSD seems excessive in terms of following original design intent though. EV west slaps those things in almost every motor they make and don't seem to suffer any ill effects at all

i emailed zero ev about their reverse pump, to ask if it impacts peak performance of the motor at all, or if you can run it in reverse at full tilt and it'll behave basically the same


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## remy_martian (Feb 4, 2019)

CantDecide said:


> 057 is where I sourced my Model S: https://057tech.com/products/driveunits
> 
> I got a clarification from them:
> 
> Which I think agrees with your idea to use the Zero EV reverse pump. I didn't know that was an option. I think 057 seems to be reluctant to deviate too far from the Tesla specs, but it seems reasonable to make some of these modifications.


It's not just the oil pump.

By running it in reverse, you've changed the gear shaft thrust loads from one end to the other. The speed limit is a horsepower limit, which is what gear loadings are sized for.

Why not just run a motor and a longitudinal gearbox in the tunnel and leave the rear end a "Corvette"? 

You can also use the Telsla drive unit (if you must...) to direct drive your driveshaft or diff pinion - Zero EV sells a taller gearset for that purpose...


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## brian_ (Feb 7, 2017)

remy_martian said:


> It's not just the oil pump.
> 
> By running it in reverse, you've changed the gear shaft thrust loads from one end to the other.


That's true of any gearbox with helical gears... which means essentially all production car gearboxes, including current EVs. Whether this is a problem or not depends on the specific bearings used; I've never seen anyone fully disassemble a Tesla gearbox and examine the bearings for suitability with reversed axial thrust.



remy_martian said:


> The speed limit is a horsepower limit, which is what gear loadings are sized for.


I don't think that's really true. Power is the product of both torque and speed, so if the limitation is power handling, then the result is not a fixed speed limit. Gear loading and axial bearing loading correspond to torque, essentially regardless of speed, and transmissions are usually rated primarily by input torque, and also by maximum speed, with no suggestion that both input torque and speed are maximized at the same time.

Of course, the Tesla gearboxes are unique to them, so there are no published capacity specifications, unlike conventional transmissions from automotive suppliers.



remy_martian said:


> Why not just run a motor and a longitudinal gearbox in the tunnel and leave the rear end a "Corvette"?


That's the classic EV conversion solution, and it is particularly attractive when the rear drive and suspension configuration doesn't lend itself well to just replacing the final drive unit. My Spitfire is an example of this, so if I were to proceed with a conversion I would probably try to place the motor in the transmission tunnel and leave the rear end alone. To leave the engine compartment available for battery modules, ideally both the motor and any gearbox attached to it fit in the transmission tunnel.

The general problems include mass balance (with the heavy motor up front as well as most of the battery), and packaging (simply fitting everything in). In the specific case of a Tesla motor, an issue is that the motor does not have an output end housing separate from the transaxle housing, so it doesn't lend itself well to pulling the motor off and using it separately.



remy_martian said:


> You can also use the Telsla drive unit (if you must...) to direct drive your driveshaft or diff pinion - Zero EV sells a taller gearset for that purpose...


That works (if you can actually get that gearset), but the bulk of the transaxle is a problem in any vehicle, and would be a huge (literally) problem in a Corvette.


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## retrEVnoc (Mar 23, 2019)

Hello from Santa Cruz!

I haven’t read every page if this thread but can offer a few things: 

Based on your timeline, Damien M AKA jack Bauer will likely have control of the M3 inverter by the time u need it. 

Model S LDU: Can’t be run upside down as the transmission fluid will drain from the vent (wouldn’t be available for the gear splasher even if it didn’t all drain out). as others have said, it will need the reverse oil pump to run it backwards. You could also find a drive unit from the Mercedes, I think they mount up stock the way you want it to fit. 

Honestly tho dude, the easiest EV conversion for a rwd car is using the GS450h transmission. There was one being parted out in San Jose not long ago. 

Contactors, be advised there are contactors with built in economizers and those meant to be run with external economizers, I’ve recently learned this the hard way. 🤬


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## joekitch (Sep 13, 2013)

retrEVnoc said:


> Hello from Santa Cruz!
> 
> I haven’t read every page if this thread but can offer a few things:
> 
> ...


just updated the op to specify a 180 lateral axis rotation with the reverse oil pump

Control of the M3 inverter would be excellent, but the open question is how much power you can get out of it. IF it peaks at 400whp, i'm not as interested for a single motor application.
even if realistically you can't really put down more than 300kw from that model s motor (as evidenced by the ev west pike's peak e36), having that full 475 on tap allows for fun hooning on demand

there's a version of this plan where i do everything except the tesla motor for now, and indeed focus on that GS450h transmission for packaging efficiency...and then i do the tesla motor later on
but that doesn't sound nearly as fun..

edit: holy shit those transmissions are CHEAP, like, under $1000 all in


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## joekitch (Sep 13, 2013)

more than a year later, i got the vcu200 in my hands, without realizing i also need to drop $300 on the leaf light hs v2 usb to can converter from kvazer

well, i dont NEED it, but considering how the vcu200 is incredibly CAN dependent for controlling everything, having a good way to write and debug can read/injection software will be very useful


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## joekitch (Sep 13, 2013)

more build plan updates:
so uh, looking like *lg chem battery bricks from chrysler pacifica hybrid minivans is the play for my build!*
assuming it's like $3k per battery pack (that's the price quoted when i called a local wreacking yard asking about theirs, i didnt even attempt to haggle), and each pack has 6 modules, that's 18 total modules for *46kwh of capacity, but only weighs 684 lbs* , assuming the 38lb number from ev west is accurate LG CHEM Lithium Ion Battery - 60.8V, 2.6kWh, EV West - Electric Vehicle Parts, Components, EVSE Charging Stations, Electric Car Conversion Kits .
9 grand for 46kwh in 684 lbs, which is only 1 pound lighter than the old chevy big block engine is.....extremely good. Even at my most pessimistic estimate of 500 watt hours per mile to rocket this shark down the highway, that's 92 miles of range which is very livable 

i'll probably go for a 3p6s config of modules to get a 364v nominal, 12 modules up front and 6 in the rear gas tank area.....although 228lbs back there might be pretty heavy considering i also have a 200lb motor and stuff
*its possible i could fit all 18 in the front battery box* (size of a chevy big block engine and also occupying the transmission tunnel) if they're as compact as i think they are which would MASSIVELY simplify ALL my wiring and cooling.

*my only real concern is lack of documentation*. the chevy volt batteries are extremely well known. These LG chems are...not as much


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## MattsAwesomeStuff (Aug 10, 2017)

joekitch said:


> *my only real concern is lack of documentation*. the chevy volt batteries are extremely well known. These LG chems are...not as much


I don't know how much documentation you really need. They're a battery. Motors and controllers are agnostic towards them.

And, that's a steal of a price. Nice score.


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## joekitch (Sep 13, 2013)

I guess it's like, if I have a question it's more likely that'll be answered somewhere online already for the volt batteries than the LG chem....

Also forgot to mention these LG chems have massive power density, bisi of bisimoto and the EV west bmw both use them and have no issues.

Also cooling will be annoying, they have no interior cooling so I'll need to design/build chill plates


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> I don't know how much documentation you really need. They're a battery. Motors and controllers are agnostic towards them.



Charge and discharge ratings, temperature limits
BMS connector pinout
temperature sensor specs
I agree - the motor and controller don't care about the battery. On the other hand, the BMS does.


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## brian_ (Feb 7, 2017)

joekitch said:


> I guess it's like, if I have a question it's more likely that'll be answered somewhere online already for the volt batteries than the LG chem....


The Chevrolet Volt batteries were made by LG Chem, too... but I know what you mean: this particular LG Chem module is not used as widely as the LG Chem modules from the Volt.

On the other hand, builders such as snowdog (with the Electric Supercar) have used the LG Chem modules for the Pacifica Hybrid.


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## brian_ (Feb 7, 2017)

joekitch said:


> Also forgot to mention these LG chems have massive power density, bisi of bisimoto and the EV west bmw both use them and have no issues.


Any battery for a plug-in hybrid (such as a Volt or Pacifica Hybrid) tends to have relatively high power density, compared to a pure battery-electric vehicle's battery, because it needs to meet operational power requirements from a relatively small battery capacity.


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## brian_ (Feb 7, 2017)

joekitch said:


> so uh, looking like *lg chem battery bricks from chrysler pacifica hybrid minivans is the play for my build!*
> assuming it's like $3k per battery pack (that's the price quoted when i called a local wreacking yard asking about theirs, i didnt even attempt to haggle), and each pack has 6 modules, that's 18 total modules for *46kwh of capacity, but only weighs 684 lbs* , assuming the 38lb number from ev west is accurate LG CHEM Lithium Ion Battery - 60.8V, 2.6kWh, EV West - Electric Vehicle Parts, Components, EVSE Charging Stations, Electric Car Conversion Kits .
> 9 grand for 46kwh in 684 lbs, which is only 1 pound lighter than the old chevy big block engine is.....extremely good.


That's without any of the cooling system, mounting structure, enclosure, interconnecting wiring, or associated devices (BMS, contactors, fuses).



joekitch said:


> *its possible i could fit all 18 in the front battery box* (size of a chevy big block engine and also occupying the transmission tunnel) if they're as compact as i think they are which would MASSIVELY simplify ALL my wiring and cooling.


Is there any uncertainty about the dimensions? If you don't trust EV West (understandable) there have been various suppliers of these modules who should also list dimensions.

18 of these modules total 210 litres (7.4 cubic feet), plus cooling, mounting, enclosure, and wiring. Would that really fit in front, given that these are rigid rectangular boxes to be fit into an irregular space?


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## mons2b (Nov 17, 2015)

MattsAwesomeStuff said:


> I love a well-documented project.
> 
> I'm converting the little brother to your C3, a blend of 1970 and 1972 Opel GTs. Poor man's C3 I suppose.
> 
> ...


I see a lot of enthusiasm for prius motors and inverters. But I have also read of actual Prius drivers having a lot of failures on the MG1 drive.


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## mons2b (Nov 17, 2015)

Duncan said:


> I'm part of our local "Muscle Car" community
> 
> But NONE of the Muscle cars can beat my "Device"
> 
> ...


What was the look on their faces? Blank? Disappointment? Anger? A mix?


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## joekitch (Sep 13, 2013)

LG chem module availability might be a lot more sparse than i suspected
on the expertise angle it'll be a little sparse as well. There's the electric supercar guy on youtube, Bisimoto who i have a good relationship with but is a very busy dude, and EV west who have painted themselves into a corner with workload and thus dont really answer emails

there isn't that much on here about the modules either, at least in depth


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## joekitch (Sep 13, 2013)

Random little update, but i finally put together the little bench test wiring harness for the VCU200 and got it talking to my PC

https://www.instagram.com/tv/CXP_V1-..._web_copy_link

this opens up CAN protocol development for the gauges and sound generator, which i'll likely do first since that's low cost but gets me a lot of experience with CAN and embedded systems

the sound generator may be a whole ass job though, i'm getting tons of conflicting recommendations of what kind of system to use to generate sounds, from using a digital audio workstation (DAW) on a raspberry pi , to programming languages designed to generate sound by code alone , to complex "event scripting" languages designed to orchestrate big audio visual experiences


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## MattsAwesomeStuff (Aug 10, 2017)

Instagram links didn't work.

However, if you just right-click copy image, and paste it directly into your reply, it will paste the image itself (not the link to the image), and be just fine.


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## joekitch (Sep 13, 2013)

Strange, not sure why they wouldn't work
But it's a little video, not an image, hence why I linked it from IG


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## brian_ (Feb 7, 2017)

MattsAwesomeStuff said:


> Instagram links didn't work.





joekitch said:


> Strange, not sure why they wouldn't work


It worked for me, but I have a currently logged-in Instagram session.


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## joekitch (Sep 13, 2013)

well this slightly sucks
i'm attempting to do more rough battery placement and the results are....not ideal

with chevy volt cells, two packs worth, barely 34kwh worth, i have to pack the engine + transmission area and gas tank area and im still one block short











on the flipside i re-did the lg chem battery placement be allow for way easier chill plate design (four larger plates instead of a ton of small ones, and the positioning seems to be excellent, fits comfortable with some room to spare











but again, these lg chem bricks are getting really scarce, i could easily be supply limited more than cash limited
also, participating in this thread, wiring these things might be much more of a pain than expected

LG Chem battery dissection | Page 2 | DIY Electric Car Forums

so im hurtling towards either a battery solution that may not even fit, or one that i can't even get the batteries for

great, i think

on a more optimistic track, i'm looking into photogrammetry very seriously after finding the results of this particular guy on reddit who did exactly what im doing, scanning the engine bay to size a battery box, and his results were pretty spectacular 
I 3D scanned my engine bay : E30 (reddit.com) 
4CcesXg.jpg (1114×1082) (imgur.com) 
z7r5Bb4.jpg (1407×1876) (imgur.com) 
i'm looking into throwing together a really good photogrammetry gear set for like $1500 of used body, lense, and ring flash, and hopefully i can get a "good enough" scan of everything i need, including the components themselves


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## remy_martian (Feb 4, 2019)

hmm


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## remy_martian (Feb 4, 2019)

Pack energy in the 30's kWh is where you wind up if you don't want a heavy pig of a 'vette.


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## joekitch (Sep 13, 2013)

ironically, 32kwh of Volt packs and 48kwh of lg chem packs will weigh about the same
of course i'll need a little extra mass for the chill plates with LG chems but if i keep the chill plate designs simple, that shouldn't add more than like 75lbs overall?

I'm constantly running the numbers on added mass and it's looking like i'll be about 300lbs heavier than a standard vette. Not small, but not that big tbh

not sure what you're pointing out in the pic? that's the front crossmember, the front radiator sits around there


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## brian_ (Feb 7, 2017)

joekitch said:


> ironically, 32kwh of Volt packs and 48kwh of lg chem packs will weigh about the same
> of course i'll need a little extra mass for the chill plates with LG chems but if i keep the chill plate designs simple, that shouldn't add more than like 75lbs overall?


As a very rough approximation, assume that the cooling plate for each module weighs about the same as a solid aluminum plate the area of the module face and 10 mm thick: that would be 362 x 203 x 10 mm @ 2.7 g/cm3 or 2 kg each so 18 would be 36 kg (80 lb). So sure, something like 75 pounds seems reasonable to me.


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## joekitch (Sep 13, 2013)

my guestimation sensor must be well calibrated then, hah

to compare mass more directly, 2 chevy volt packs will be 435lbx2 or *870lbs*, although that includes their casing so it's an overestimate
18 of those lg chem bricks, at 38lbs each, comes out to* 684lbs*, which gives me 184lbs of wiggle room for cooling, and i still gain a good 16kwh on top of that

as a potential fallback, if i go for 12 bricks instead, i get the same kwh as the Volt packs of 32kwh, but I'm down to *456lbs* for ALL my batteries, *which means I might even SAVE mass* from the stock c3 weight.... although my *range will probably be shit (73 miles* at the nominal 80% battery capacity + using 350 watt hours per mile which is probably optimistic given how insanely crappy the drag coefficient of this shark is)

plus, at 12 bricks, i can fit all of my batteries into the engine-bay-battery-box extremely easily


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## remy_martian (Feb 4, 2019)

I, too, was going for the V8 look on the C5, then realized it cost me a block of batteries (you can get one more between your "heads") and it raised the CG if you didn't stick one more block in. 

I was pointing out you should also have space for one battery block, transverse to your "engine", in front of it.

The hood is closed 99% of the time and the big dogs have a piece of plastic on top of an ICE to give it a V look, anyway, these days. Underhood plastics always bugged me.


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## joekitch (Sep 13, 2013)

sorry remy, i'm a direhard car boi so under hood eye candy is super important to me, see the icon derelict mercury EV, which looks gorgeous with the hood open









that said i can actually keep the batteries low in the frame (using the transmission tunnel for instance) and use other components to act as "valve covers" to get that sweet v8 look. the Mercury uses the inverters as their valve covers for instance. i could put my dc/dc converter and HV junction box up there and give them similar dimensions and nice aluminum covers.

that said, some more weight napkin math
456lbs of batteries, 80lbs of cooling, 290lbs of motor (not including coolant, battery box mass, cabling or secondary bits like chargers and converters) = *826lbs*
575 small block chevy engine DRY, 100lbs for my TKO500 manual transmission, 100lbs of exhaust including mufflers, 156lbs for the 28lbs gas tank with a full tank of gas (not including coolant/oil mass plus fuel lines) = *931lbs*

so they're already extremely close, within 100lbs, and i save even more weight vs a big block engine (which weighs more like 685lbs)
this 12 battery configuration is looking nicer by the second...especially if DC fast charging or my charge generator trailer idea pans out....
but even at 18, i only gain another 184-and-a-bit lbs of mass for another 16kwh of capacity which is huge, another 36 miles of range at 80% capacity and 350 watt hours per mile

this c3 might not actually be pigfat after all


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## remy_martian (Feb 4, 2019)

Yes, the eye-con Merc inspired me as well (the Merc goes for a flathead look, actually)...then reality took over. He built a "lead sled" (car guy term) vs a handling sports car. Everything is a tradeoff, which is why builds are different.


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## joekitch (Sep 13, 2013)

i think most of the extra mass in that mercury is from needing to use a full model s pack worth of batteries, that's a good 1000lbs in batteries alone, in order for the C rating not to be poop.

but yeah, weight balancing will be a problem. i really need some kind of cad program which can model mass distribution with some rough accuracy (especially the exact location of the CG in 3d space). perfect 50/50 is probably a pipe dream but I would really like 55/45

12 lg chem bricks instead of 18 sounds like the play, really


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## remy_martian (Feb 4, 2019)

Yup. 12. Now the trick is getting the voltage or current you need....you have to trade acceleration/topspeed using gearing because it's only 12.


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## joekitch (Sep 13, 2013)

that's the nice thing about these LG chem modules, they get full 364.8 nominal voltage at 6p since they're 60.8v a pop
so all i need is 2p6s and boom, I'm golden.
3p6s with 18 bricks is just a bonus.
They're also pretty power dense even if not the absolute best (their rated max discharge current is 800amps for 10 seconds) so i shouldn't see much issues with C rating at 2p


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## brian_ (Feb 7, 2017)

joekitch said:


> ... but yeah, weight balancing will be a problem. i really need some kind of cad program which can model mass distribution with some rough accuracy (especially the exact location of the CG in 3d space). perfect 50/50 is probably a pipe dream but I would really like 55/45


Embrace the spreadsheet. Front-to-rear balance is pretty easy: for each component you enter the distance from your reference plane (e.g. one of the axles), calculate the moment as that distance multiplied by the mass, total the moments and divide by the mass to get the distance from the reference point to the centre of mass. Start with the stripped car as one component (you'll have to get axle weights).We're only talking about a couple dozen components, so it won't take much longer to do than to decide to do it; the effort is just picking the distances out of your CAD model (or back of napkin drawing).

This might be considered low-tech; I think of it as appropriate-tech.

You can do the same thing for lateral and vertical positions, in the same spreadsheet if you want.


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## UglyCarFan (8 mo ago)

remy_martian said:


> hmm
> 
> View attachment 126148


joekitch: I like the overall look of your rendering with modules forming the basic shape of a V8. I realize others have done this before. It might work to laser out a front plate to serve as a frame stiffener, leading edge of a battery restraint system, potential mounting surface for other components, etc. If it helps with your project, I have local access to extremely heavy heat sinks that come out of those giant wind turbines. My favorite scrap yard gets them, as the mfg is just down the street. I've purchased a few in the past, at about 68# each. You could mill them down to save weight. The base plate is about 1/2" thick, the fins are about 6" tall. Overall size about 15" x 23". I'm going from memory...I bought the first one as a heat sink for a buddy who was building massive Class A amplifiers.


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## joekitch (Sep 13, 2013)

Gigantic update since i haven't touched this thread in months.

Lost my job back in august, recently signed an offer for a new one, started buying parts again

Parts got:

got the bms-18 master and 5x satellites from legacy EV
got a raspberry pi as well as the PICAN3 shield, for canbus stuff
got 2x round LCDs off alibaba, for my realdash component. (i still havent loaded realdash onto a second pi yet...)
AEM EV inverter control board for the tesla LDU, it now supports the sport drive unit too.
fluke 374fc for reading current
fluke 3000fc for accurate voltage reading and logging
Charging and bms:

the aem ev ccs controller is still MIA, no idea when it's happening.
Learned that for a ccs system to work, there need to be separate contactors just for charging, hooray more $140 contactors
I'll be using ev west's little battery parallel board module things, with the plan to parallel the boards across 3 modules each, so in total there will be only 96 "cells" with each cell being 3 cells paralleled across 3 modules. This is to get around the fact that a full bms 18 system can only pin for 96 cells
I'm looking reallllllll hard at the model 3 power conversion system for ac charging and dc/dc converter, they are only $600 for a good one with harnesses, and damien's little control board is $311  , its an 11kw charger which is extremely powerful

Weight distribution:

only moments ago i realized a single 18 module front battery box is going to make this thing handle like absolute hot dog water. i used a little free weight distribution tool to get a rough estimate and ouch









there's a lot of unknowns here but i dont think the rest of the car is going to make up for a weight discrepancy that big.....
this is with a 784lb battery box up front using the stock motor mounts, a 291lb LDU in the back, and a 50lb charger box thing where the gas tank was
If i split the box in half, 12 modules up front (552lbs) and 6 in the back(278lbs), things get significantly better, 49/51. although of course install complexity goes waaaaaay up, ESPECIALLY if i want to do dc fast charging which requires its own contactors


Scanning and measurement:

i did a full photogrammetry shoot of an empty c3 engine bay from a c3 forums member, 











threw it into tinkercad, and did some rough sizing on a front battery box
this is with all 18 up front, it actually fits pretty well? 









i will of course be doing some kind of v8 looking setup, probably with upper chambers that house some high voltage junction box + VCU200 stuff put into a V shape


Battery fun:

I got the batteries, 18 chrysler pacifica hybrid modules from tech direct club, $500 each, not sure if i posted that here yet?
i did a static discharge test two months after getting them, using a nice used fluke multimeter...
turns out two of the modules have some bad cells, and the tech direct club guys don't do returns unless the degradation is COMICALLY bad, like more than 1v out of spec, which seems insanely bad to me
so those two might be used for some kind of big semi-portable battery backup or something, but i'll need to get two new modules, likely from ev west (they found a good supplier of brand new modules) for $800 each

Canbus fun times:

i'm trying to do a full benchtop setup with the VCU, and an RBPI with a pican3 shield, to set up my goofy sound synthesis system. Getting the vcu to just put out some status can messages is proving difficult
its likely i'll need to have a pretty sophisticated bench setup, with the LDU + inverter control board installed, plus a fake HVIL loop, plus a fake ignition key, plus a fake PRND switch, plus a fake HV contactor signal.....just to get the CAN2 bus to put out some basic data i can sniff for

Diagrams n'sheit:

I'm finally starting to make some wiring and coolant route diagrams. they're woefully incomplete, but lucidchart turns out to be very good at this kind of stuff






















I'm slowly removing unknown unknowns and replacing them with "man this gon' be a bitch innit?"

also patiently waiting for the aem ev ccs module, which i really hope isnt more than $1500, and ev west to release the corvette rear suspension as a weld-it-yourself flat pack...which i really hope that isn't more than $2000


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## remy_martian (Feb 4, 2019)

I would not exceed that 552lb (still need to add 50 or so for a box) up front unless it was a big block car.

It is tempting, though, with all that empty volume and it's siren song of "fill me up".

The V look is secondary. The hood is not open, or made of glass, as you are cursing in a curve at the over 800lb you stuck in the front, turning it into a pickup truck for handling.


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## joekitch (Sep 13, 2013)

The 552 is conservative as it's 12 * 38lb batteries with an extra 100 for the box, controllers, wiring, and anything else going on up there


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## MattsAwesomeStuff (Aug 10, 2017)

joekitch said:


> Lost my job back in august, recently signed an offer for a new one, started buying parts again


Well that's backwards. Should've bought parts when you were unemployed and had spare time to work on them 



> Learned that for a ccs system to work, there need to be separate contactors just for charging, hooray more $140 contactors


So...









TE Connectivity EV200AAANA 500a 0-900vdc Tyco 12/24v


These were recovered from EV battery modules. These are VERY EXPENSIVE online. If you have any project that needs a high current relay this is your chance to save some money. Make a cheap 30a BMS into a 500a BMS. This will work for batteries in the 9-36v range so perfect for Lifepo4 and Lithium...




batteryhookup.com





These were $15/ea during their black friday sale.



> this is with a 784lb battery box up front


Ugh. A half ton under the hood? No bueno.



> If i split the box in half, 12 modules up front (552lbs) and 6 in the back(278lbs), things get significantly better, 49/51. although of course install complexity goes waaaaaay up, ESPECIALLY if i want to do dc fast charging which requires its own contactors


Muoy bueno.

...

Looks great. Glad to see you're stick plugging away at this.


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## joekitch (Sep 13, 2013)

The ev200s are good for high amp performance applications yeah? They're listed as 500amp continuous and single-time disconnect at 2000amps, which should be above my fuse threshold anyway..... 

Can it also be used as a precharge contactor? Although I imagine a somewhat beefy 12v automotive relay can do the same thing for precharge for even cheaper


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## remy_martian (Feb 4, 2019)

Precharge current is pretty low - a contactor is way too big for the job and requires a high current driver for the coil, unlike the size needed for a relay.


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## MattsAwesomeStuff (Aug 10, 2017)

joekitch said:


> The ev200s are good for high amp performance applications yeah? They're listed as 500amp continuous and single-time disconnect at 2000amps, which should be above my fuse threshold anyway.....


Yeah, they're OEM hardware out of other EVs. BMW's if I recall correctly.



> Can it also be used as a precharge contactor? Although I imagine a somewhat beefy 12v automotive relay can do the same thing for precharge for even cheaper


Sure. They used to have a 900v 100A relay that was half the price, that I was going to use, but, I bought up a ton of EV200s on their sale, so, I might just use them. I was an idiot, I should've bought like, a lifetime supply of DIY EV tinkering.

They have built-in economizers too.

You could use a 12v auto relay, but, that's not going to be happy with more than, oh, 35, 50v? Not that there would be much power flowing, but, if you for reason did want to shut it off, I imagine if you tried to interrupt the arc it would frizzle right through the airgap quite merrily. An auto starter relay, probably fine, but, is that any easier or cheaper than $30?


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## remy_martian (Feb 4, 2019)

Again...you have to drive or switch a contactor coil with a lot of current compared to a relay.

It's not as low cost or as interchangeable as you think it is.

An economizer is meaningless in a circuit that operates for 1 second, by the way.


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## floydr (Jun 21, 2021)

TE Connectivity EV200AAANA (1 )
High Voltage Relays, 1 Form X, SPST-NO, Flying Leads, Stud Terminals, External Economizer, Power Switching, 500 A, 900 VDC, Kilovac EV200 
KILOVAC EV200 Series Contactor .PDF
Holding Current (Avg.) [email protected], [email protected] 

Don't know how this compares to a relay.
later floyd


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## remy_martian (Feb 4, 2019)

Inrush current 3.8A is what matters for a driver or switch. Precharge is on for less than a second, and inrush is about 12% of the time, with no hold time to speak of (in other words, it's not a power limited spec, but a current limited one).


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## joekitch (Sep 13, 2013)

Interesting, but then, what are the specs to look for in a precharge contactor/relay for a 360v battery pack? I'd imagine anything similar to the p115 specs as I see that thrown around as a precharge contactor very often, question is if there's a junkyard equivalent you can get off some car, much like the ev200 from BMWs


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## floydr (Jun 21, 2021)

TE 2138011-1 RELAY 
2x 9-36V 200A CONTACTOR/RELAY 1x 135A RELAY 1X 350A FUSE MODULE BMW 4596753-03 sold out  I missed them not sure of the model of BMW they came out of.
later floyd


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## MattsAwesomeStuff (Aug 10, 2017)

floydr said:


> TE 2138011-1 RELAY
> 2x 9-36V 200A CONTACTOR/RELAY 1x 135A RELAY 1X 350A FUSE MODULE BMW 4596753-03 sold out  I missed them not sure of the model of BMW they came out of.


Those were the deal of the decade. Sold out long ago.



remy_martian said:


> Again...you have to drive or switch a contactor coil with a lot of current compared to a relay. It's not as low cost or as interchangeable as you think it is.


Well, then what cheaper-than-$15 relay suitable for 360v+ are you suggesting be used?

I'd toss in a relay that controls the contactor as my halfassed driving solution.


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## remy_martian (Feb 4, 2019)

Again, for the third time, you are missing the point. Look at the coil side. Something has to drive or switch a lot of current.

If you're tossing in a second relay, welcome to a reliability hit.


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## floydr (Jun 21, 2021)

Here is another
Littelfuse DCNLEV50-BAN This is sold as a precharge relay/contactor
Max Coil Inrush Current: 
B: 461mA Max to Coil 12V coil 8-16V DC 
C: 250mA Max to Coil 24V coil 16-28V DC
E: 122mA Max to Coil 48V coil 33-52V DC
later floyd


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## joekitch (Sep 13, 2013)

remy_martian said:


> Again, for the third time, you are missing the point. Look at the coil side. Something has to drive or switch a lot of current.
> 
> If you're tossing in a second relay, welcome to a reliability hit.


i'm also having trouble following, are you saying the precharge contactor needs to be smaller because the amps to trip the coil side aren't that much? Basically, what makes a good precharge contactor/relay as opposed to a main contactor/relay in terms of specs?


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## remy_martian (Feb 4, 2019)

You have to switch current in the coil.

For a contactor, that coil current is huge.

For a relay, it's modest.

I seriously doubt the precharge coil driver output on most controllers is sized to switch 3.8A.

It's a caution. You need to determine what current your system is capable of driving without killing the circuit. You can't just willy nilly swap in a $15 1000A contactor to do a 15A job and then be surprised when you've smoked your VCU.

Look at the specs on the coils, look at the specs on what switches the current to those coils. Being Mr Cheap where the flashing lights and pretty colors of $15 could cost you another $2200 VCU buy is your choice.

I've wasted enough time on this.


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## joekitch (Sep 13, 2013)

did a little digging in the documentation, and ominously, the vcu only mentions precharge in the context of their PDU-8 power distribution box thingy, which seems to imply only the pdu-8 can drive the precharge contactor out of the box...? That seems a little silly, likely the vcu can drive stuff but at significantly fewer amps












edit: nevermind i'm blind, also they use precharge and pre-charge interchangeably in similar documentation










3.3a is absolutely not much, and yeah will need a specific relay for high voltage but low current


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## MattsAwesomeStuff (Aug 10, 2017)

It's not the end of the world. Use a cheap transistor to boost the power if you're worried. 3.8A is a lot, but it's only for 1/10th of a second. 

Again, or a relay. Your ignition on a normal car doesn't trigger the starter solenoid directly, it goes through a relay too. A nonissue.


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## remy_martian (Feb 4, 2019)

It's a reliability issue. You have to package the transistor, mount it, and protect it from the elements. An added relay is a point of failure....they don't like sitting out in the elements with contacts open.

Don't add unnecessary shit to nickel and dime your build - it's a false economy that compromises reliability and time to failure.

A fail-to-start tow will buy you a half dozen contactors, to put it in perspective....it could cost you even more if a neighborhood turns sketch at night and your car full of copper won't start, and I'm not just talking about money.

Drive the precharge relay directly off the AEM port. A proper, automotive-rated one that does not push the limits of the spec sheet max. They exist. Buy a new one, wait for one, salvage one.

A high current contact needs a lot of current in its coil to keep it closed at low resistance...










or a $15 one


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## MattsAwesomeStuff (Aug 10, 2017)

remy_martian said:


> It's a reliability issue. [...] An added relay is a point of failure....they don't like sitting out in the elements with contacts open.


Oh come on now, you're being paranoidly pedantic.

How many relays are under the hood of a car, and how often do you ever have to replace one? Most cars, not even once in its 20+ year lifespan?

And you're suddenly worried that it might fail?

It's a DIY project, if that's your consistent level of paranoia, then never build anything. And, never buy anything, because OEM automotive standard itself isn't even high enough for you.

As I said, a relay to operate the coil on a starter solenoid is the way almost every single car of the last 6 decades has been made. Now OEM isn't even good enough, you have to be even better than that on a DIY build?


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## piotrsko (Dec 9, 2007)

Ever hear of a SSR? Not the 1000 amp ones on fleabay for $20 either


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## remy_martian (Feb 4, 2019)

It goes against every grain of my being as an engineer to see a 1200A relay being used to switch 15A or adding Rube Goldberg lashups like "just add a transistor", but it's not my project, and not my VCU that was going to get cooked with the stright replacement you originally suggested.

Do what you want.


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## schelle63 (Jan 3, 2018)

If I understand correctly, the point is how to realize precharge.
If not, just forget this post.
If yes, may I add the diagram of a Th!nk A266's precharge system (built from 1999 to 2001), in fact it is 2 systems (one for the main (= controller) contactor, one for the auxiliary systems (= DC/DC, heater, charging...)).
There is no relay/contactor, it is a simple MosFet which does the job, and some tiny little PTCs (3 parallel) are sufficient to limit the inrush current. After precharge is done (some seconds), the corresponding relays close and the big current can flow.
Of course, a (small!) relay also can do the precharge (as I see in many modern cars), but somehow I like this old stuff, and keep it (as long as it works).
I hope this helps someone.
Markus

P.S. could someone tell me the difference between a "relay" and a "contactor", please?


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## floydr (Jun 21, 2021)

schelle63 said:


> P.S. could someone tell me the difference between a "relay" and a "contactor", please?


Good question. Seem much of the industry uses the two terms interchangeably examples TE EV200AAANA is called a relay here yet it s called a contactor in the datasheet, TE 2138011-1 is called both a contactor and a relay here , Littlefuse DCNLEV50 is called both here
Later floyd


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## remy_martian (Feb 4, 2019)

A contactor is a class of relay generally used to connect or disconnect a high current/voltage power supply.


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## brian_ (Feb 7, 2017)

schelle63 said:


> P.S. could someone tell me the difference between a "relay" and a "contactor", please?


Originally, a relay relayed information, meaning that the controlled output was used as a signal (information, not power). A contactor is a switch, operated by some mechanism, to provide power to some controlled device. Common usage has degenerated to small devices are called relays and big ones are called contactors, approximately.


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