# First Build - Miata1 (working title)



## DaveEV (7 mo ago)

I found a donor, not sure if I made best decision but I'm excited about the project! Facebook Marketplace had a 2014 Nissan Leaf available for parts. The battery was already spoken for, but the drivetrain and high voltage components were available, as was most of the interior. We agreed on a price, and they let me disconnect the pieces I wanted to not get cut (wires, hoses). Then they said they'd give me the whole front subframe, as it saved them time! Yikes! But okay! Feeling good that I have clean wires from J1772/CHAdeMO ports to batttery plug to start from.

In addition to the whole stack (with only one coolant line cut), I got the radiator/condenser assembly with the electric water pump, the drive selector, and accelerator pedal assembly. Eventually, I'll need to figure out how to control it all. I passed on getting any brake or steering system parts, as the Miata has lots of depowered steering and brake vacuum options.


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## DaveEV (7 mo ago)

As I build this thread, realizing I've missed a lot of pictures. I've used a chain hoist to move the Leaf subframe and motor. That is definitely a safety hazard, pics would have been worth it. I'm sure there will be more! Also, I asked Facebook if anyone wanted the gas out of the Miata. Someone had the setup I didn't want to spend money on (yet): 5gal gas can, 12v battery, 12v fuel pump, and hose to connect to the supply line in engine bay. Just connected everything and took the gas out. I'm sure there is more in there, and I'll drain it eventually, but building community! May have made a connection to local machinist, more to follow.

I've taken a few things off the Miata: muffler, emissions lines, brake vacuum lines, fuel injector harness, power steering lines. But the big news is I've separated the Leaf drive unit (can I use LDU or too confusing with Tesla LDU/SDU?) from the subframe. Axle nuts loosened and removed with cordless impact, but I needed to buy the right size socket and adapters. (I ordered sets of both as I'm planning for future use.) It took a bit of wrestling to get the axles out of the hubs, but eventually they came out without having to remove any more steering or suspension pieces. Then removed left, right, and rear motor mounts and lifted the drive components up and slide the rest of the subframe out from underneath. With any luck, I'll find a buyer for that thing who will haul it away.


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## DaveEV (7 mo ago)

Got a little work done this weekend. I've seen a couple teardowns of the Leaf DC/DC and inverter, but at this point I'm not that interested on whats inside or taking it apart. So, I
left all the cables on the DC/DC, removed the A/C compressor, disconnected hoses and cables from the motor, removed the 6 bolts mounting inverter to motor, removed the cover and 3 bolts for each phase of the electrical connection on the motor, and lifted the inverter from the motor. It took some leverage and shims, but more or less came straight up and off!





















Bungees helped keep everything together until I got in my little shed. The are hard to see below, but there are guide pins to help keep things aligned when assembling inverter and motor.


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## DaveEV (7 mo ago)

I sized the Leaf radiator and Leaf Drive Assembly (LDA is what I'll call it from now on) to see what might fit. The radiator is about 3 inches too wide, so I'll find a Miata one and use that. I am fairly convinced that the LDA can fit in back, possibly including the inverter and DC/DC. I need to drop the rear subframe to remove the fuel tank, so I will have both on the ground to confirm some measurements and see if I can get a fabricator over to look at what needs to be done to the subframe. I'm sure one of the cross members will need to be cut, but not sure if it's possible to make some sort of alternative.














I did a little of the prep work to remove the subframe. I'm going to try and leave the brakes connected until I'm sure about what I'm doing with the LDA. It's ready to come down, just need a second set of hands.


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## windraver (Aug 29, 2021)

I found it's best to use the stock radiator of your car in almost all cases since it already fits your chassis. Since the system doesn't run that hot, you can actually opt for a smaller radiator. For my case my CRX had a "half radiator" which I used. 

The only part from the leaf you want from the radiator is the water pump when it comes to cooling since it's an electric water pump.


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## DaveEV (7 mo ago)

Wow... pulled off the fuel filler neck and there's a wee bit of rust...


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## windraver (Aug 29, 2021)

DaveEV said:


> Wow... pulled off the fuel filler neck and there's a wee bit of rust...
> View attachment 131640


Good thing you don't need it anymore!


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## DaveEV (7 mo ago)

Contemplating my driveline decision, any thoughts from the community are appreciated...

Can't find Miata manual trans on Oahu. car-part.com lists one, but I called the yard and it's gone
I did find great deal on BMW Getrag 5 speed. I'm in touch with KMiata who has a swap kit, see if they'll package together just what I need for direct drive (EM57->adapter/coupler->Getrag->custom driveshaft->miata diff)
Have local machinist coming early next week to look at LDA and Miata subframe for possible rear mount... That means subframe is coming down soon!

I might wait for a Miata trans as the KMiata kit will be pretty pricey. And I'll probably get impatient, miss out on the Getrag, and be left with the LDA rear-mount... What does this group think?


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## windraver (Aug 29, 2021)

If you go with the coupler to driveshaft approach, you should see @Electric Land Cruiser build

If you decide to relocate the EM57 to the rear (which is really small btw), you will just need custom axles and you can reference my build.

I would suggest taking a look at the size of the actual leaf EM57 motor and comparing it to the Miata drivetrain and see what the size difference is. From what I've taken away, there is much of a benefit of keeping our manual transmission despite the fact I really do miss the fun of shifting through gears.

And before you actually decide all the above, figure out where you can actually place the batteries. Keeping them together really makes the project easier but the Miata is basically the same size as my CRX so you really don't have much room to place those batteries. That might determine where and how you place the motor, inverter, and PDM. Extending the PDM, inverter, and motor wiring is many times easier than battery BMS wiring extension because the BMS wires may be high voltage and you'll need safety cut offs.

When I was considering the coupler adapter plate approach, I found this here:



https://bratindustries.net/



They have both coupler and adapter plate which solves the Leaf half of the work. You'd then need a machine shop to help you mate the other half.


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## remy_martian (Feb 4, 2019)

@Bratitude ^


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## Electric Land Cruiser (Dec 30, 2020)

I would recommend mounting the drive unit in the rear like Windraver says. A manual transmission takes up valuable space and weight for no appreciable gain. That is if the LDA can fit in the rear subframe of the Miata, it might fit but it would be tight. The gas tank is above it which when removed would provide clearance. Miatas are tiny, tiny cars. If I was doing a small sportscar build I would do a MR2 Spyder with Leaf drive unit in the rear, half the battery in the rear, half the battery in the frunk. That would be an awesome car. Like Windravers CRX but RWD.


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## DaveEV (7 mo ago)

Electric Land Cruiser said:


> I would recommend mounting the drive unit in the rear like Windraver says. A manual transmission takes up valuable space and weight for no appreciable gain. That is if the LDA can fit in the rear subframe of the Miata, it might fit but it would be tight. The gas tank is above it which when removed would provide clearance. Miatas are tiny, tiny cars. If I was doing a small sportscar build I would do a MR2 Spyder with Leaf drive unit in the rear, half the battery in the rear, half the battery in the frunk. That would be an awesome car. Like Windravers CRX but RWD.


Thank you both! Definitely following the both builds as I want to Toyota truck after this, and the CRX has similar space issues. I really like that BlackBox which would be great for everything RWD/4x4, including this Miata. 

I'm dropping the subframe and fuel tank this week, having a machinist friend come over and talk about possibilities. I'm sure there is space (maybe even with inverter mounted), just some cutting and welding to be done. I don't have a battery yet, so not sure what my DC/DC and BMS look like. Rear mount would definitely clean up the battery issues you've identified for me, thanks for making sure I'm considering that. I think if I had a Leaf pack I'd have to split between front and trunk regardless. Almost time to start measuring and planning that stage!


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## DaveEV (7 mo ago)

With a little help from some friends, I've dropped the subframe and gas tank. I couldn't break either axle nut, need MORE leverage! Not sure popping the axles out of the diff was a good idea, but I had help and really wanted to get that gas tank down! I only cut one wire group, which I'm pretty sure was for the pump. I still need to go back and get all the fuel lines and junk out, but it sure seems like there is a LOT OF ROOM! Can't wait to start measuring things out!









I took off lower control arms from subframe, disconnected UCA at hub. I stripped one of the swaybar hex bolt things, so that's staying on for now.








Trying to use some plastic bags to keep the gunk out. I'll either reuse or try and sell the differential.








Can't see them, but bungies are holding the brake calipers. There were a bunch of little 10/12mm bolts for the fuel lines, filters, whatever canister is in that box... But tank has 4x 14mm bolts. Probably good mounting points if part of the battery pack ends up going here. Your thoughts?








Rear subframe with UCAs and differential still attached. Forward is toward top of photo. Should be solid for mounting the LDA, either forward or reverse, but one of the crossmembers is going to need reconstruction. 








This sure seems like a lot of room! Maybe mount LDA in reverse, swap some wiring, and mount 1/3 of battery pack here. Thoughts?

I hope to give the LDA, subframe, and maybe the diff to someone who can get it mounted. Probably have them do the axle mashup too, so I can get that all measured right. Does anyone have this done already? I need to check the NB vs RX8 track and axle specs, maybe InductiveAuto's EX-8 has good template for axles?

Battery is probably next big step. Hoping @windraver and I can figure out how to ship 48 Leaf modules to Hawaii!


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## DaveEV (7 mo ago)

Apparently my NB Miata track width is 1440 mm Rear, and RX8 is 1505 mm. Also, one guy succinctly says NC Miata and RX8 half-shafts are not interchangeable at either end. Couldn't find NB :/ But maybe I almost know the pieces and sizes now? Miata outer, EX8 (less 32.5mm[65/2]) shaft, Leaf inner?


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## DaveEV (7 mo ago)

Gas tank is all the way out, and it looks like I'll be able to sell the pump and float unit. Nice. Since I'm going to mount a part of my battery pack up here, I'm wondering if I could cut the tank and use as a base. It already has holes to mount to chassis, maybe needs some reinforcement. Feedback appreciated!








I think mounting the motor in the rear is too much. There are some other things I could try, but I'll try to be a little more straight forward. Drive assembly is two wide to fit between lower control arms, in both front/back and left/right directions.


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## GassedOut (9 mo ago)

DaveEV said:


> Gas tank is all the way out, and it looks like I'll be able to sell the pump and float unit. Nice. Since I'm going to mount a part of my battery pack up here, I'm wondering if I could cut the tank and use as a base. It already has holes to mount to chassis, maybe needs some reinforcement. Feedback appreciated!


Gas tanks are pretty thin metal. I doubt it would have much structural integrity (and more importantly, battery-supporting strength) once it's no longer a fully boxed shape. But, if you were to cut away most of the skin and use the mounting points to build back in a reinforced frame, I could see that being useful.

For years, I wanted to do an engine swap on my Miata -- K-series, Ecotec, LFX -- but sinking that much money into a dying technology (ICE) was hard to justify. Converting it to electric kept tempting me, but every time I researched it, I was dissuaded by the packaging difficulties you're encountering. I'm hoping battery density improves dramatically in the coming years, but I'm definitely following your build with interest in the meantime!


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## Electric Land Cruiser (Dec 30, 2020)

DaveEV said:


> View attachment 131736


Above that panel is the parcel shelf, between it and the trunk there is even more dead space. You can access it from the interior if you remove the seats and soft top. I think the LDA will fit in the subframe. Make a jig to hold the important parts and cut away what you dont need then weld in bracing. It actually looks really promising! The LEAF drive unit is pretty small.


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## windraver (Aug 29, 2021)

If you take off the existing motor mounts, the motor is quite small. There are a bunch of excess parts that don't need to be on the motor. Even in the CRX, a very small car, it might've been possible to rear mount the motor.


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## Tremelune (Dec 8, 2009)

If you can fit it where the diff is without having to reengineer the suspension, that would be huge. Like, you'll have to cut and weld, but as long as you didn't mess with the mount points, axles can be made for a grand. The gearing is good, and you'd have a lot more space for batteries. Cool project.


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## DaveEV (7 mo ago)

Thanks everyone! I've made a couple decisions on the build, execution updates to follow:

Abandoning rear mount. but i'm already considering next build with RX-8 or NC Miata (multilink rear suspension) and EM61 Leaf motor. From my measuring and setting things on top of each other, I'd need to hack the LDA as well as the subframe to keep suspension mounts in same place. I might be wrong, but too much drama and risk.
I picked up a BMW Getrag 5-spd and two driveshafts (different lengths). Non-Miata trans means I'll ditch the PowerPlant Frame (PPF). Aftermarket has supporting equipment, more to follow. Will be going clutch-less. Gives me several gear ratios to decide what is acceptable... maybe more power will overcome so...
I have an OpenInverter board on its way. Definitely interested in hacking more power out of the motor, will save 200kW for the next build  And will allow modular updates to the system if/when it's time to update battery.
Finding a battery is challenging. Easiest route is to buy a whole vehicle. BatteryHookup says they will ship batteries on a pallet. I'm hoping that's true so I don't have to waste time/money on getting rid of what I don't need. In any case, I'm setting up AC rectifier for test environment.

Maybe the gas tank will just be a template for the rear battery box, but I'll consider cutting and reinforcing. I'll definitely look under the parcel shelf and see how much space might be gained with a little more cutting. I do want to leave that in place to minimize complications to putting the top down.


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## GassedOut (9 mo ago)

This might give you a better sense of the space under the parcel shelf:



Subwoofer Install



I think NB's are pretty similar to NA's there, but I'm not overly familiar with them.


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## remy_martian (Feb 4, 2019)

I've gotten two pallets of "batteries" from BH - was fairly painless - the pretty much crossed the full width of the Con-US. 

Picked them up at my local freight terminal, where the freight carrier forked them into my trailer.


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## DaveEV (7 mo ago)

Just a little more specifics on my battery challenges, in case someone has better ideas than me. Lithium Batteries are considered Class 9 UN3480 HAZMAT. Shipping via air or ocean requires a bunch of extra packaging and handling requirements (ref: UPS) and batteries must be less than 30% charged. Of course, if installed in original equipment (eg vehicle), rules are different. Current Connected says they can do it for $60-490 per cell, which I'd need 54 cells to get to 200V pack (or 108 to 400V). So that's minimum $3000 for shipping, plus DHX cost (another $3000?), and still need to add cost of actual batteries. I had a quote for a San Jose area shipper for about $5500 for a full Leaf pack, broken down. I'm still waiting to hear back from Battery Hookup, but I suspect they will ship it to a DHX embarkation port and I'll have to cover from there.


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## DaveEV (7 mo ago)

GassedOut said:


> This might give you a better sense of the space under the parcel shelf:
> 
> Subwoofer Install


That's a good use for that space! NA and NB are pretty much the same. The gas tank comes up through the trunk between frame rails, while the trunk sits over the frame rails. That leaves dead space in the trunk above the rails on both sides of the gas tank. Then the parcel shelf sits on top of the gas tank. 

I'm not sure how usable it will be for the battery pack. I'd have to cut the trunk and install through the trunk, rather than from below like the gas tank. Might get me room for a couple modules. It's about time to start that Cardboard Aided Design. 

Since I'll have HV run to the rear, I'm also considering some of the management/disconnect equipment in that space. My brain can't process it all, really need a wiring diagram. What does everyone use to build their diagrams?


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## remy_martian (Feb 4, 2019)

You should be lurking patiently on the Hawaii salvage car auctions


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## DaveEV (7 mo ago)

remy_martian said:


> You should be lurking patiently on the Hawaii salvage car auctions


Don't tell anyone, but it looks like a 2011 Leaf with a new battery is on the block for Tuesday. I'd pick up an EM61 to reconsider that rear mount and a decent 24kwh pack. Also, another Miata with "mechanical" damage and no engine video


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## remy_martian (Feb 4, 2019)

Don't worry - I've looked there, then the shipping quote kicked me in the gonads.

Good luck at the auction...


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## DaveEV (7 mo ago)

Well, in good news, I found a battery... In a slightly damaged 2013 Leaf at IAAI.com auction!  I couldn't walk the lot, everything is online, so I'm unsure of battery condition. Going to see if I can find my OBD adapter and download LeafSpy, more to follow. (And to close the loop on the 2011 mentioned above... It keeps showing up on the next week's auction, so I think the reserve is too high $3000+)

In the meantime, I've bought and installed a VAG electric vacuum pump, the (almost) matching pigtail, vacuum switch / relay, and some various mounting gear. I'm pretty pleased with how the rubber strip and sign bracket hold the pump and mount to the body. Picked up some hose and clamps from Napa and reused some wires I had around. I just need to add the 12v+ to the pump/relay and it's good to go! I hope the horizontal mounting doesn't affect it too much.


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## Mack the nife (5 mo ago)

Our company did a lot f Miatas , very simple conversion , kept everything in place , removed the engine , gas tank and put a net gain AC system in it made a coupler and adapter plate for the motor to trans , put most LiOnP4 batts in the trunk area and a row in front where the radiator was , ran very well , took 6 days to do


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## Electric Land Cruiser (Dec 30, 2020)

Mack the nife said:


> Our company did a lot f Miatas , very simple conversion , kept everything in place , removed the engine , gas tank and put a net gain AC system in it made a coupler and adapter plate for the motor to trans , put most LiOnP4 batts in the trunk area and a row in front where the radiator was , ran very well , took 6 days to do


That's awesome! What capacity batteries did you use?


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## Mack the nife (5 mo ago)

180AH ,36. Cells


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## DaveEV (7 mo ago)

Mack the nife said:


> Our company did a lot f Miatas , very simple conversion , kept everything in place , removed the engine , gas tank and put a net gain AC system in it made a coupler and adapter plate for the motor to trans , put most LiOnP4 batts in the trunk area and a row in front where the radiator was , ran very well , took 6 days to do


Yes, looks like it could be pretty simple. I seem to have chosen not to go that route  Did you repurpose the space where the gas tank was? Did you reuse the mounting points from below, or cut through the sheetmetal in the trunk and drop in from the top?

Other updates:

2013 Leaf battery health is 57%. I charged fully and it showed 55 miles of range, 7 bars of health. Sounds about right.
And then a 2011 battery came available for cheap. Its supposed to be 5 bars of health. I picked it up before anyone else could. It's going to be a lot of work and weight for minimal range, but really good experience.
So, debating to sell the 2013 i got at auction for a little profit (if I can) or keep for next conversion and use Resolve EV (I checked, I have AZE0, should work).
Speaking of the hard way, I bought an OpenInverter inverter board for the learning (and potential performance increase.) It currently has a design or printing error that prevents CANbus comms, but I was able to find a local electric shop that salvaged a resistor off the original Nissan board to use. I've got it booted and connected to my WiFi

any tips on checking state of the battery (SOH) on the floor of my garage without cracking it and charge cycling each cell?


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## electric_skids (Jul 15, 2019)

Edit: just saw you've found a transmission so don't worry, just some thoughts 🤗

Wanted to throw in my 2 cents with avoiding a manual transmission, hopefully you can fit the motor where the fuel tank was, behind the seats.
Then attach motor straight to the rear differential, provided the gearing can be adapted to work.
Matching, via gearing ratios, motors most efficient RPM to wheel rotations (also RPM i guess?) at your preferred cruising speed.
Alternatively match motor max RPM to desired top speed.

This guys audi ev conversion blog explains the maths alot better


Advanced electric vehicle conversion project



But anyway doesn't matter which way you choose to go about it, long as your enjoying the process!

I love my NB miata aswell, hoping to do this one day.

Good luck!! keep up the great work


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## Electric Land Cruiser (Dec 30, 2020)

I would use the 2013 battery over the 2011 definitely. They both have horrible degredation but the '11 battery might just fail outright, they have worse chemistry and build quality than 13+.


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## DaveEV (7 mo ago)

Electric Land Cruiser said:


> I would use the 2013 battery over the 2011 definitely. They both have horrible degredation but the '11 battery might just fail outright, they have worse chemistry and build quality than 13+.


I disassembled the 2011 battery this weekend. I'm definitely concerned on it's condition. Looks like it must have been sitting outside for a while and some water got in. I don't think it flooded though, just lots of condensation.

















My guess is most of the modules are "good", but I think I need to fully cycle them a time or two for capacity measurements and voltage matching prior to connecting any BMS.

For fitment, I'll have to go back through your LC and other builds. The fuel tank space could probably hold 12 modules fairly easily, but I'll need to "fold" one of the side groups so they are 2 wide, 6 high. I might be able to fit another 4 or 8 there, but complicates the HV bus and BMS wiring. The last rear space, other than the trunk, is where the muffler was. Probably best for four, but maybe reconstruct the trunk floor to get rid of the spare tire space and use for whatever remaining batteries need to fit. 

I need to get my motor and trans mated and mounted, but rough plan is to break the large group in half and stack vertically or horizontally in engine bay. Might not end up as a 50/50 split, but hopefully just two large pieces.

So physically, battery pack will be split 50/50 front/rear and fairly accessible (worst being fuel tank area which on Miata is still not too bad). Electronically, this pack was already iffy and now everything is questionable. I do think the areas on beneath rear deck on either side of fuel tank will be ideal for contactors and DC/DC converter. Aside from the state of the battery, everything is looking good!


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## electric_skids (Jul 15, 2019)

Looking good. Bit moist but not too bad. Cycling each pack on a discharge tester sounds like a good idea, will also tell you how many Ah they are actually holding.
In the meantime maybe store them somewhere they can dry out? Maybe under A/C (cooling mode) indoors or plastic closed off bag with moisture absorbent.

Also you gonna keep the clutch between motor and trans? Cause the odd clutch kick and drift around corners (responsibly) in miatas is heaps of fun.


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## Wayne Alexander (10 mo ago)

Please don't take this a wrong way , I'm not trying to offend any one , I have done many Mazdas there dirt simple to convert . About three days is all that is needed. . just stand back and look at it ,, what makes it GO . A gass engine . What do you do to make it electric ,, Replace the engine with an electric motor , NO , it's not that simple , remove everything that makes the ICE work , engine , gas tank , exhaust , fule lines , pump.
Trans, we make our own adapter plates and couplers , so the E motor and trans go back in fast , one day .
Next se cut out an are in the trunk / boot area to install the batt cells , cables go in, controller goes in .wireing is done , day 2 , a row of cells where the radiator sat , day three is for checking everything and so on ,. I see people trying to reinvent the universe with a stone ax , why beat your head on the street , I see so much unnecessary work and expencsis spent on a simple conversion . But if your not in a position to have a full machine shop and a good source for parts and batteries , I can understand . maybe a helper ,, like common sense , no disrespect, just an observation.
,


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## remy_martian (Feb 4, 2019)

Wayne Alexander said:


> we make our own adapter plates and couplers , so the E motor and trans go back in fast , one day .* * *
> I see people trying to reinvent the universe with a stone ax , why beat your head on the street , I see so much unnecessary work and expencsis spent on a simple conversion . But if your not in a position to have a full machine shop and a good source for parts ....


OK..so if you make Miata adapter plates and couplers, why aren't you offering them for sale in this forum's classifieds?


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## Electric Land Cruiser (Dec 30, 2020)

Wayne Alexander said:


> Please don't take this a wrong way , I'm not trying to offend any one , I have done many Mazdas there dirt simple to convert . About three days is all that is needed. . just stand back and look at it ,, what makes it GO . A gass engine . What do you do to make it electric ,, Replace the engine with an electric motor , NO , it's not that simple , remove everything that makes the ICE work , engine , gas tank , exhaust , fule lines , pump.
> Trans, we make our own adapter plates and couplers , so the E motor and trans go back in fast , one day .
> Next se cut out an are in the trunk / boot area to install the batt cells , cables go in, controller goes in .wireing is done , day 2 , a row of cells where the radiator sat , day three is for checking everything and so on ,. I see people trying to reinvent the universe with a stone ax , why beat your head on the street , I see so much unnecessary work and expencsis spent on a simple conversion . But if your not in a position to have a full machine shop and a good source for parts and batteries , I can understand . maybe a helper ,, like common sense , no disrespect, just an observation.
> ,


There's "converting a car to electric " and converting a car to electric in a way that maximizes battery size and power and balance etc. Otherwise we'd all just have forklift motors and lead batteries.

What is the range, power, weight etc of your builds?


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## MattsAwesomeStuff (Aug 10, 2017)

Wayne Alexander said:


> I have done many Mazdas there dirt simple to convert . About three days is all that is needed. [...] *I see people trying to reinvent the universe with a stone ax , why beat your head on the street , I see so much unnecessary work and expencsis spent on a simple conversion.* But if your not in a position to have a full machine shop and a good source for parts and batteries , I can understand . maybe a helper ,, like common sense , no disrespect, just an observation.


Mhm.

So, yeah, if you're a professional facility with a full machine shop and machinists and a working relationship with an existing scrapper who pulls exactly what you've already decided you needed and sends it to you, and you just throw money at the problem, and you're just following the exact same thing you've done in the path with no custom decisions, then it's a simple task. Perhaps.

This is an amateur making decisions about what he wants to convert and what path to take.

So like... absolutely nothing in common with the situation you've described as "dirt simple" and takes 3 days.

I also notice you didn't elucidate any of your criticism or advice in a helpful way. In fact, I can't find a single useful thing in your post that anyone could take advantage of. Just a bunch of handwaving and thinly veiled insults (which you don't intend to offend anyone...) about the choices being made... without describing what could be done instead.

"You're building your house wrong. It's not that hard. You just put it up in 60 days. Everyone's wasting so much time here talking about how they want their house built. You just need a full team of tradespeople working and then the house is built. First you pour a foundation, then frame it, plumb it, sheet it, run electrical, drywall, paint, and then furnish it with all the belongings you'd want inside. It's so easy and you're making it complicated." Great. Wonderful. Thanks for sharing.

What are the "unnecessary work" items being done? What is being "reinvented"?

If you have a script for him to follow that is universally perfect for every person who'd ever want to convert a Miata, then, by all means, give him the script that will need no interpretation or customization.


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## Wayne Alexander (10 mo ago)

I had them up for sale on my web site , and found that the day builders won't a my price , they always wanted them for next to nothing , the is a business not a charity . And now. Find out my original sign name is working , so me and mack the nife are the same people . Any way the business is being sold off and can finally move back to o Florida . Probably my last post


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## MattsAwesomeStuff (Aug 10, 2017)

Wayne Alexander said:


> I had them up for sale on my web site , and found that the day builders won't a my price , they always wanted them for next to nothing


Well that's the problem with people who run businesses thinking that they're entitled to customers regardless of the value they create. So many businesses overcomplicate things and have so much unnecessary work and expenses. They think that just because it took them a long time to make, that it has a high amount of value. They blame the market for not creating special rules for them, rather than looking inwards and being efficient and reaching a pricepoint that is worth paying for. Really just common sense and some people don't have it. No disrespect just an observation.



> Probably my last post


A real shame, that. You had so much more you could've given, like, defending anything you ever said. Oh well.


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## DaveEV (7 mo ago)

Long post, I guess it's been a while... 

Yes, I actually haven't seen the details of too many Miata builds. I've seen finished photos, a few pieces here and there. I reached a point I was confident I could make it happen in my backyard, learning as I go. I don't know anyone who welds or works in a machine shop, so I am asking around. So far, haven't gotten anyone to stop by though I've had a few leads... I just got an angle grinder, so together with my screwdrivers and socket set, I'm making good progress. Speaking of which...

Finally got under the dash and removed the ECU and wiring harness. Hoping to recoup a few bucks there, and I think it marks the end of stripping the Miata. Yay!

I'm getting more confident that I can fit the whole leaf battery. Fuel tank space will have 2x2 modules on edge and 2x6 flat. Then 8 where the muffler was, or maybe 6. I haven't worked out exact configuration but I should be able to reuse bus bars except for the pack behind the axle (muffler). AND the stack of 24 should fit in front if I remove the stock radiator! It would be angled, parallel with the hood, but it leaves space underneath for the motor and to the sides for inverter and accessories. My mock-up was a little long, so happy to have the pack sitting in my garage to take measurements..

Battery boxes will be a challenge. I think I can reuse the bases from the various groups by cutting, and should be able to find bolts long enough for the 2x6 to reuse the compression brackets. I am getting tempted to move forward without welding and instead bolting sheet metal and brackets together with some sealant. I haven't seen this done as everyone seems to weld... Thoughts?

Some pics of the 2x2 behind the 2x6, next to fuel tank they replace. The 2x2 will sit lower and at an angle, unless I make custom compression brackets and rotate 90 degrees. 


















Motor adapter and coupler are inbound from @Bratitude and transmission mount inbound from v8roadsters.com. I may have my kid sneak the coupler and clutch disk to school and see if someone in shop class can follow instructions to machine, fit, and weld together. Big picture, I'm hoping this all leads to something people (eg students) can come to a shop I setup for conversions and volunteer some hours (they need 40 hours to graduate).

Whew, that was a lot, and probably enough for tonight. More work this weekend, I'll try and update as I go!


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## Electric Land Cruiser (Dec 30, 2020)

Wayne Alexander said:


> I had them up for sale on my web site , and found that the day builders won't a my price , they always wanted them for next to nothing , the is a business not a charity . And now. Find out my original sign name is working , so me and mack the nife are the same people . Any way the business is being sold off and can finally move back to o Florida . Probably my last post


Well you're certainly doing an excellent, top notch job promoting your business like for instance showing us photos of your builds and a link to your website....

You came in here calling names and saying we live in the stone age and you can convert a Miata in a week.

Then you complain that nobody wants to buy the Miata you converted in a week....


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## MattsAwesomeStuff (Aug 10, 2017)

Electric Land Cruiser said:


> You came in here calling names and saying we live in the stone age and you can convert a Miata in a week.


FWIW, I'm not doubting who he is, what he's done, or what he can do.

I'm just saying it's utterly useless to offer naysaying and discouragement without giving any details what-so-ever of what is being done wrong, nor what could be done better.

It's like saying "You're doing it all wrong, that'll never work". Let's say that comment is correct ... what is the person being criticized supposed to do with it? They can't even stop what they're supposedly doing wrong, or do something different, because no details were given. So all that's affected is that this enthusiastic person now has lower motivation, enjoyment, and passion for project. What a miserable thing to do to someone.

Doesn't really matter to me how accomplished or successful you are. That's a sh!tty way to treat people.


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## DaveEV (7 mo ago)

Appreciate the support! I understand I don't have experience, and love constructive comments on the build and what I'm posting here (and elsewhere). My goal here is to document some of my challenges and successes, and leave a trail that people with similar challenges might find, so others can see if what I do might work for them. I'm on a budget and don't have a full tool set, so I could definitely be doing things an easier way!

I do see a bunch of metal cutting in my future. I should find a fabrication shop, but who doesn't love power tools? More on all that later. 

Tonight I removed the clutch pedal and mounted the Leaf accelerator pedal. I found some brackets I had removed from elsewhere and only had to drill a hole in the floorboard, everything else had mounting holes that aligned. It feels solid, a little low, but I get full travel and it's well spaced from the brake pedal.


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## wstein25 (12 mo ago)

GassedOut said:


> This might give you a better sense of the space under the parcel shelf:
> 
> 
> 
> ...


I'm in the middle of an NA conversion. I pulled the gas tank and cut away lots of sheet metal to make way for 2 Tesla Model S battery modules. I just posted with pictures a couple of hrs ago.


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## DaveEV (7 mo ago)

wstein25 said:


> I'm in the middle of an NA conversion. I pulled the gas tank and cut away lots of sheet metal to make way for 2 Tesla Model S battery modules. I just posted with pictures a couple of hrs ago.


Looking at that, I think I understand what others were trying to tell me earlier. The space on either side of the tank adds just enough to fit one of the Leaf side packs, and with a little more trimming I can fit four high. So, 16 (4x4) Leaf modules will go above the frame, behind the seats.

















That leaves plenty of room for 8 modules (2 2x2) between the rails below, if I can figure out how to mount them.









I've reassembled the busbars to fit the 4x4 pack. The BMS leads fit fairly well, but I'll need to extend 4, in the correct order, up from the other 2x2 packs below the frame. So, it looks like half the pack is pretty solid.









These mods should be fairly easy to replicate, both the cutting and grinding in the Miata, and reassembling the Leaf packs in 4x4, 2x4, or even the 2x2 that I'm planning. More pics on the packs to follow!


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## DaveEV (7 mo ago)

Just realizing I'm behind on updates here, but at the moment I am wondering if anyone knows the wiring on the Leaf drive selector? It has 9 (EDIT not10) of 12 pins in connector filled. I'd *really* like to reuse it!

EDIT: Moved this to a separate thread in technical discussions.
Another EDIT: Was pointed to this earlier thread from 2019. It's a move in the right direction, but the question was never fully answered...

And some updates on the build coming soon!


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## DaveEV (7 mo ago)

DaveEV said:


> The BMS leads fit fairly well, but I'll need to extend 4, in the correct order,


Well, I didn't think the BMS through. Definitely would have been easier to take the Dilithium BMS leads, solder some O-ring terminals to the ends, and install them all before mounting the pack. I did keep the Leaf wires and plugs, and am joining those to the BMS leads. Lots of time with the multimeter has been spent, lots of time with the soldering iron in the future. Good news is, my daughter was into soldering the first 24 leads... just 73 more to go... 

From the rear pack, I've started running HV cable forward. So far, just to safety disconnect which I am mounting in center armrest. 


















I also found a shop to finish my coupler fabrication. I tried to show him the guide, but he just wanted to listen to me explain. Looks like I did well enough! The adapter so I can bolt motor to transmission is in the works.










And I also took a first stab at 3D printing enclosures for motor and inverter cabling. Cable glands fit, but need a little tweaking to mount fully. Not sure if I'll need to reprint.


















I don't foresee any major problems other than fabrication. Once I get motor and trans together then I'll need to find someone. And maybe getting the OpenInverter board wired and configured correctly without letting out any of the magic smoke.


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## DaveEV (7 mo ago)

I'm just about done on the rear half of Miata1EV. I'm going through the rest of what I need to keep the battery safe and what needs to be at the rear half of the pack. I plan to use as much of the Leaf stuff as I have, so that includes the three contactors from the module in the battery pack and the two contactors for the CHaDeMo charging. It looks like the charging contactors also have an economizer circuit, so I'm excited I may have everything to make DC charging work.

Speaking of economizers, I can't find info on whether the ground, precharge, and main contactors have them. They seem easy enough to control, just add 12v and go. (I'll update with wire colors). I'll measure current draw when I'm off the keyboard, but does anyone know? I plan to keep this group together, probably mount with forward battery pack.

Even though I've cut metal and mounted the fuse and safety disconnect, I'm tempted to move those to the shelf behind the seat. Otherwise, I just need to run the B- cable from the rear pack to where the contactors will be. I was not planning more contactors for the rear pack, but am wondering if that's a good idea from safety point? If so, just one between the packs, like the safety disconnect?

My attempt at text wiring diagram:
Inverter B- - ground contactor - 5 feet HV cable - rear pack (-/+) - mid contactor(?) - safety disconnect - 400A fuse - 5 feet HV cable - front pack (-/+) - precharge/main contactors - Inverter B+

Also, I had thought the Leaf's inertia switch would be near the contactors, but I can't seem to find it physically or online. Maybe it doesn't have one? I'd like to add that to the wiring for the contactors.

I'm also stuck on early on in calibrating my OpenInverter board. I have a thread on that forum asking for some help.

Hope everyone is enjoying their weekend and making good progress on their projects!


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## remy_martian (Feb 4, 2019)

Your "safety disconnect" needs to be at the battery box, not in an armrest. There should be zero length of cabling going to it, or something close to zero.

A safety disconnect is not an e-stop.


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## DaveEV (7 mo ago)

remy_martian said:


> Your "safety disconnect" needs to be at the battery box, not in an armrest.


Thanks @remy_martian. I interpret that as you agree I should move the disconnect from the center armrest to behind the seats, which is where the rear battery box is, and would do a second disconnect for the front box. 

I haven't seen anyone build with two disconnects. The Leaf disconnect (is "service" better than "safety"?) has 24 modules on either side, which is what I was trying to replicate. Granted, that disconnect is connected to the one Leaf battery box, so maybe not the best design to follow.


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## remy_martian (Feb 4, 2019)

What you have is ok for a _service_ disconnect if it splits the pack.

Being left with more than 60V outside a battery box is not "safety".


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## GrayRaceCat (Jul 13, 2021)

DaveEV said:


> Thanks @remy_martian. I interpret that as you agree I should move the disconnect from the center armrest to behind the seats, which is where the rear battery box is, and would do a second disconnect for the front box.
> 
> I haven't seen anyone build with two disconnects. The Leaf disconnect (is "service" better than "safety"?) has 24 modules on either side, which is what I was trying to replicate. Granted, that disconnect is connected to the one Leaf battery box, so maybe not the best design to follow.


The Contactors _are_ the safety disconnects. The Service plug is for the technician's safety when the battery pack is to be removed or opened for repair. If you want something to kill power from the armrest in the cabin, break the _12volt feed_ to the contactors. I think that's what the "Cut Loop" does on a Tesla.

Since you want to split the battery weight front to back, and you can't accurately predict which HV circuit might suffer a short in a crash (either can be lethal), I would recommend dual contactors in both battery boxes, HV+ and HV-, and a safety disconnect for each box too. You don't want arc-flash to be the way you discover a fault, like a welded contactor, in either box. To recap, 2 contactors, HV+ and HV-, and 1 safety disconnect per box, and split the potential in each box in half if you can, better safe than sorry.


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## GrayRaceCat (Jul 13, 2021)

DaveEV said:


> Thanks @remy_martian. I interpret that as you agree I should move the disconnect from the center armrest to behind the seats, which is where the rear battery box is, and would do a second disconnect for the front box.
> 
> I haven't seen anyone build with two disconnects. The Leaf disconnect (is "service" better than "safety"?) has 24 modules on either side, which is what I was trying to replicate. Granted, that disconnect is connected to the one Leaf battery box, so maybe not the best design to follow.


Another thought I had is this. The Miata has an Airbag/SRS system, right? Does it disable the fuel pump(s) in the event of a crash? If so, could you use that to break the 12v circuit to the Contactors instead of the fuel pump?


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## brian_ (Feb 7, 2017)

GrayRaceCat said:


> The Contactors _are_ the safety disconnects. The Service plug is for the technician's safety when the battery pack is to be removed or opened for repair. If you want something to kill power from the armrest in the cabin, break the _12volt feed_ to the contactors. I think that's what the "Cut Loop" does on a Tesla.
> 
> Since you want to split the battery weight front to back, and you can't accurately predict which HV circuit might suffer a short in a crash (either can be lethal), I would recommend dual contactors in both battery boxes, HV+ and HV-, and a safety disconnect for each box too. You don't want arc-flash to be the way you discover a fault, like a welded contactor, in either box. To recap, 2 contactors, HV+ and HV-, and 1 safety disconnect per box, and split the potential in each box in half if you can, better safe than sorry.


This sounds like a lot of hardware, but it makes perfect sense... and it explains one reason that production EVs do not have multiple battery packs.


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## Tremelune (Dec 8, 2009)

I mean, does it? In a collision, the batteries could short in a ton of ways no matter what you do with contactors. If the pack is split, it's still a single circuit that isn't grounded to the chassis, so an open contactor, fuse, or service disconnect will nullify danger unless you touch the batteries themselves.

This is a bit morbid, but collision safety in decades-old cars is a bit semantic...I thought the contactors were more about precharge than anything else. Shouldn't the fuse be what protects in the event of a short?


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## GrayRaceCat (Jul 13, 2021)

Tremelune said:


> I mean, does it? In a collision, the batteries could short in a ton of ways no matter what you do with contactors. If the pack is split, it's still a single circuit that isn't grounded to the chassis, so an open contactor, fuse, or service disconnect will nullify danger unless you touch the batteries themselves.
> 
> This is a bit morbid, but collision safety in decades-old cars is a bit semantic...I thought the contactors were more about precharge than anything else. Shouldn't the fuse be what protects in the event of a short?


In a collision, it's about isolating the HV battery from the rest of the vehicle for occupant and first responder safety, which is one reason for the contactors. Also, when an EV is powered on, the battery (DC) side of the drive circuit is always at full potential. Without contactors to break this connection on power-OFF, the traction battery would drain while the vehicle is parked.

Yes, if the battery is damaged in a way that shorts the case to the HV circuit inside, contactors and fuses won't help. HV batteries are usually in metal cases that are not electrically isolated from the chassis, leaving the possibility that after a collision, parts of the vehicle's body could be "hot."

I may be wrong, but It is my understanding that the purpose of the Precharge Circuit is to prevent voltage spikes that could otherwise damage HV components on power-up, and it has little or no effect when powering down. (I remember reading once that it may help to prevent pitting/burning of the contacts that is the result of arcing on disconnect.)


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## D&VsEVJeep (Dec 9, 2021)

Remember that not only do you have to have a connection to the high voltage side of the battery, but also the low voltage side for current to flow... AND...the path through you needs to have a lower resistance than the path through somewhere else. Both sides of a battery are monitored and isolated from the vehicle. So, if you have a bad accident and the high side shorts to the chassis, the low side should still be isolated. If it ALSO shorts to the chassis, chances are that the current will find a path much lower in resistance than a human (absolutely NOT saying this is a SAFE situation in any way)...

Typically the pre-charge or slow-charge resistor only prevents the in-rush of current before closing the main contactors. The main contactors are typically housing the contacts in a vacuum (hence the name GIGAVAC) which helps with the arcing if opening under load.


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## Functional Artist (Aug 8, 2016)

GrayRaceCat said:


> I may be wrong, but It is my understanding that the purpose of the Precharge Circuit is to prevent voltage spikes that could otherwise damage HV components on power-up, and it has little or no effect when powering down. (I remember reading once that it may help to prevent pitting/burning of the contacts that is the result of arcing on disconnect.)


Yes, purpose of the precharge circuit is to slowly fill the capacitators (in the speed controller) so they don't have to see or "deal with" a huge "in rush" of energy, on "power up".

The purpose of a discharge circuit is to "drain" any residual energy, still in the system, after "powering down" because the capacitators & cabling (from the battery box all of the way to the speed controller) continue to "hold" energy, for a while.


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## brian_ (Feb 7, 2017)

Tremelune said:


> I mean, does it?


It does.



Tremelune said:


> ... In a collision, the batteries could short in a ton of ways no matter what you do with contactors. If the pack is split, it's still a single circuit that isn't grounded to the chassis, so an open contactor, fuse, or service disconnect will nullify danger unless you touch the batteries themselves.


If the idea that breaking the circuit at any one point is enough, then EVs don't need contactors on both positive and negative... but they all do. Service disconnects are not needed at all if you can count on contactors to always work.



Tremelune said:


> Shouldn't the fuse be what protects in the event of a short?


No. That's like saying that a fire extinguisher is all that is needed for fire safety, so it's okay to build anything entirely of flammable materials with random ignition sources, because if a fire starts the extinguisher will put it out. Fuses reduce the consequences of an electrical failure, but it is better to avoid that failure (a short circuit).


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## DaveEV (7 mo ago)

Lots of good points that I'm just catching up on. Also, light bulb came on regarding the weird thin wire, clearly not HV, on my Tesla that says "CUT HERE TO DISABLE HV" (or something).

So, things I'm taking under consideration:

OEMs have ONE pack, with HV contactors and a service disconnect (which I assume has 1/2 pack on either side so highest potential is ~200V)
I have two packs, so if following what seems like OEM safety, I would have - and + contactors for each, as well as service disconnect for each pack, with 1/2 voltage on either side 400/2 = 200/2/2 = 100v highest potential, if that makes sense
Plus one more contactor for precharge resistor so I don't fry anything on voltage surge.
I didn't think to look for the stock inertia switch/impact sensor for the airbag... previous owner had steering wheel replaced, not sure if it is even there

What I am planning (at the moment, maybe changes again?)

Service disconnect between the two packs (~200v each)
OpenInverter board controlling precharge and main pos contactors, both from 2014 Leaf, through ground switch
On/Run controlling main neg and rear HV contactors through relay to ground
All 5 contactors getting pos 12v through First Inertia Switch and large "CUT HERE" loop

The rear pack is split 8/16 modules with easy access to the connecting cable. I'm not sure how the front pack will look until I know motor, inverter, and transmission are mounted well, but probably will not put a manual disconnect on that pack.

Thank you all for the input. More updates coming, I've been spending a lot of time getting my BMS wiring correct. I'm definitely doing it the hard way and have thought of starting over once or twice..


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## floydr (Jun 21, 2021)

DaveEV said:


> OEMs have ONE pack, with HV contactors and a service disconnect (which I assume has 1/2 pack on either side so highest potential is ~200V)


200VDC is still dangerous, Plus the idea behind the service disconnect is to isolate the HV battery to the battery box or so I thought.
Later floyd


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## Tremelune (Dec 8, 2009)

Random thing to be aware of: Some BMSes will fry if they bridge a circuit that gets cut, so you have to be sure you're not straddling modules when the BMS is powered but the contactors aren't connected. Ditto service disconnect.


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## Functional Artist (Aug 8, 2016)

DaveEV said:


> Lots of good points that I'm just catching up on. Also, light bulb came on regarding the weird thin wire, clearly not HV, on my Tesla that says "CUT HERE TO DISABLE HV" (or something).
> 
> So, things I'm taking under consideration:
> 
> ...


FWIU here is a quick diagram/drawing (example) of what the battery pack (box, contactors, service disconnect & HV cables) may look like, in a vehicle with a split pack 

* Notice how the modules, contactors & service disconnects are all "inside" the boxes








The drawing below illustrates how "when" the contactors are "off" there shouldn't be any HV (heavy blue) outside of the boxes 








Hope it helps


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## DaveEV (7 mo ago)

Tremelune said:


> Random thing to be aware of: Some BMSes will fry if they bridge a circuit that gets cut, so you have to be sure you're not straddling modules when the BMS is powered but the contactors aren't connected. Ditto service disconnect.


That's a good point! The way my rear pack is setup a disconnect would not perfectly split the pack (24 cells/24cells), but at 16 cells/32 cells. The Dilithium BMS splits in groups of 12, so... It looks like I will place the disconnect next to the rear positive contactor. 

The drawing is close to what I'll have, thanks @Functional Artist . I just need to change the relocation of the rear service disconnect I mentioned above, and add the pre-charge contactor and resistor next to the front positive contactor.

I really appreciate this forum! Lots of support here, and info from others' projects!


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## scotta1725 (Nov 9, 2017)

I am in the process of planning a conversion (so way behind you Dave).
Do you really need all these contactors? Just thinking about added expense and additional points of failure?
This is the HV circuit I had in mind; Contactors at the 'most' positive and 'most' negative ends. The battery pack fuses are externally removable (ie. operate both as a fuse and service disconnect.) 
From what I can glean it appears to be the wiring that conversion companies like ZeroEV are using. Happy to be corrected.


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## D&VsEVJeep (Dec 9, 2021)

@scotta1725 It is all about how safe you really want to be... 

We will have the added expense of a second contactor on each pack to disconnect any possible higher voltage from being on any conductors outside the battery boxes when the contactors are off (under normal operation). I also believe the additional contactors offer redundancy in case a contactor is fused... I.e. if the - ve contactor in your diagram fuses, you won't know it and then if the system is supposed to be "off" and someone grabs the two cables coming out of that rear battery box...they will be surprised... Of course, you have the service disconnect too which would open this...

Again, all I can say is it is kind of up to you on how safe you want to be. There are no real rules and you can find even some big "professional" companies doing some pretty potentially unsafe things, IMHO. I had several long discussions about this at SEMA and some people were very insistent that only the main contactors are needed even with split packs and any additional contactors are just a waste of money...


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## scotta1725 (Nov 9, 2017)

Thanks. Really interesting how 'best practice' is evolving fast. 
I suppose that having the removable fuses (also acting as service disconnects), cutting both +ve and -ve on each pack could achieve a similar isolation objective. 

I would have loved to have made it to SEMA!


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## DaveEV (7 mo ago)

scotta1725 said:


> Do you really need all these contactors? Just thinking about added expense and additional points of failure?


A good question, and I don't have the answer. And maybe the answer is related to safety or price...

Not sure how much shipping us for you, but batteryhookup.com is having a sale that ends today! DC contactors with economizer for $15 USD.


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## GrayRaceCat (Jul 13, 2021)

floydr said:


> 200VDC is still dangerous, Plus the idea behind the service disconnect is to isolate the HV battery to the battery box or so I thought.
> Later floyd


The contactors cut power to the HV leads before they exit the battery box, isolating it. The Service Disconnect cuts the pack in two, ideally 50/50 but anything close will do. Between these three the HV is both isolated and roughly halved.


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## GrayRaceCat (Jul 13, 2021)

scotta1725 said:


> I am in the process of planning a conversion (so way behind you Dave).
> Do you really need all these contactors? Just thinking about added expense and additional points of failure?
> This is the HV circuit I had in mind; Contactors at the 'most' positive and 'most' negative ends. The battery pack fuses are externally removable (ie. operate both as a fuse and service disconnect.)
> From what I can glean it appears to be the wiring that conversion companies like ZeroEV are using. Happy to be corrected.
> ...


If the fuses are to serve as Disconnects as well, I would not put them next to the Contactors, but on the other side of the batteries so they could be used to isolate the lead between the battery boxes. Contactor at one end, Fuse at the other, and the box is isolated. As you have it, if you were in the USA, you would run afoul of the Federal Regs on voltages over 60 outside the battery box after a collision.


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## DaveEV (7 mo ago)

Wow, it's been a while. Can't even remember exactly where I left off! So first, some updates!

Holiday's were great! But I was traveling so didn't do too much with the project. Now that I'm back, I've been focused on trying to finish up the motor/trans adapter (thanks @Bratitude!) and get the @Thunderstruck MCU wired and installed. I'm pretty sure that's done, except for the chademo controls, but we'll see if I ever get there. I've also gotten started on rewiring the connector to the Leaf inverter so I can use the non-CAN controls.

Quick note... Depin the connectors you won't use and see if the pins will fit the connector you WILL use! Pretty sure I've cut 13 wires at the wrong end and will either need to re-solder them or find new connectors that will fit...

If anyone wants to verify this I'd appreciate it, but at first glance the pins from the ROUND connector will fit the inverter connector, but...









the pins from the SQUARE connector are too big!!


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## DaveEV (7 mo ago)

One thing I am feeling pretty good about is the drive selector. Once the wires were in place, I needed to add a couple diodes to make sure latching relays functioned how I wanted. I forgot about that in my diagram and it was driving me nuts. Finally had it working on the bench, but need the diodes to prevent the Set switches for Fwd and Rev from Resetting themselves, but still allowing the Park switch to Reset both.










My favorite part is the look now that its installed. Yes there are easier ways to wire drive selection, but this is soooo worth it to me!! End result is Key Switched 12v providing signal high for fwd and rev. Park resets both to open. Just need to finish the inverter wiring and connect these inputs.


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## DaveEV (7 mo ago)

Now that the @thunderstruck MCU is (mostly) wired, I thought I'd jump in and see how it was configured. Thunderstruck asks for battery cell and charger info when you buy the MCU and preloads the configuration. Everything looks good for the Leaf cells, and I wasn't sure what charger I would use so they naturally left it configured for their TSM2500.

I do only have the rear pack installed and wired, but just wanted to verify BMS was configured correctly and reading the cells correctly... Kinda good. BMS looks configured correctly, but something is wrong. Very likely user error, as my rear pack has a little reconfiguration between cells 32 and 33. Still, I don't know how my wiring could cause these voltage readings. For refresher, nominal voltage for Leaf cell is 3.65V.









What the heck is happening with cells 31 and 32? it's not at a multiple of 12, so the BMS connectors all seem right. If the leads were to the wrong cell, I'd get 0 or some multiple of 3.65 (V nom), right? MCU is not showing a hardware fault. It's got to be my wiring, but what? Inadvertent ground?

For those about to open Calc, (5.590+1.982)/2=3.782, and C1 to C32 measures 120.4v (32x3.75=120). so maybe this module has issues? I'm not excited about digging into this pack...How could the BMS wiring be done incorrectly to get these values? I appreciate your thoughts!


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## floydr (Jun 21, 2021)

I would try swapping c31 and c32 leads.
later floyd


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## remy_martian (Feb 4, 2019)

HV safety is the *only* reason to have contactors.

An inverter, AC unit, heater, etc can be permanently connected to the HV battery and be shut off electronically -- no need for precharge to protect the inverter in that event.

Shock hazard.

Not shorts.

Shorts causing fires are why you have fuses

Any cable cut during a collision will weld/melt anything near the plasma arc. No regular fuse on the planet will help you.

A pyrofuse would, though....those almost never come up in discussions here. Detect a crash and sever the fuse before the metal tears the wiring.

A service disconnect cuts current, not voltage. While voltage may be cut in half, it does not make anything inside the battery box less lethal in most cases. Electrocution at 360V is still electrocution at 180V...Mr Death doesn't care.

There's a requirement to drop to below 60V in under 5 sec on all high voltage leads (assume a short in the other polarity...a short to chassis WILL NOT blow a fuse) after a crash. The additional contactors are not optional unless you want first responders standing around watching you bleed out in your DIY electrified Lambo with two contactors missing from the build.

Nothing has changed. Awareness of the need has changed...and it's slowly diffusing to others carrying the message of a requirement vs an option. A recent posting here suggests it's "best practices" to kill high voltage on all leads coming out of a battery box (yes, that includes BMS sense wires which are just as lethal as the fatties)....no, it's a *requirement*.


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