[eg0n]

Hi folks,

I’m considering dipping my toes into EV conversion with an International Harvester Scout II (don’t have the donor vehicle yet). I’d love to get some opinions and reality checks after reading a bunch of build log threads and wiki content (super helpful, thanks so much!).

The vehicle would be used as a commuter and daily driver. My range requirement is minimum 50mi (my commute is 35mi each way and I have charging at both ends). Ideally 80-100mi. Charging at work is free so round trip work-home-work would be great (this may also require fast charging to get enough juice for the round trip during a regular work day?).

Performance-wise it doesn’t need to be too zoomy. Top speed of 75 would be great but 65 would be fine and 55… doable.

Budget maybe $20k on top of the donor vehicle. Not trying to max out everything, obviously spending less would be preferable, but I understand it’s not a cheap hobby

I have basic auto mechanics skills (serviced my own cars in the past, never pulled an engine or anything tho) but planning to take it slowly and learn, and willing to pay a professional to do things that are outside my reach. Also have basic metal fab skills - made a lot of knives and done some blacksmithing, but not a lot of real machine shop work. Happy to pay professionals here also. Can grapple with CAD and electronic/PCB design, and am skilled at both forward and reverse engineering of software, firmware and hardware. Fine with wiring, soldering, etc.

I have most of the tools listed on the wiki in all sections and will acquire anything I need and don’t have.

Some initial thoughts:

1. I’d buy a Scout with a manual transmission
2. I’d like to reuse existing knowledge and designs as much as possible as I’m not gonna be able to knock up an adapter plate or coupling at work in a machine shop like I see a lot of folks do. Might need to pay someone to help design and fab something here if there’s not something in existence that’ll do the job.
3. From what I’ve read many of the Scout transmissions are identical to Jeep trans so this may influence selection to try to reuse work others have done on Jeep conversions
4. Likely keep the clutch for safety and simplicity
5. I’d love to keep the option of 4x4 in future, or at least not make design decisions that rule it out (like ripping stuff out) if it’s not a huge trade off
6. Fine with losing all of the bed to batteries at least to begin with, and then later work out fitting battery boxes wherever else they can go
7. Don’t care about heating/AC (I live in California)

I haven’t made any decisions on parts yet.

My first questions:

1. Ridiculous? Not gonna happen? Too ambitious for someone who’s never pulled the engine out of a car before? Considered starting on something simpler like putting an EV West kit on a bug for my girlfriend, but go big or go home
2. Would a Leaf part swap work here or is the Scout gonna be too heavy? The battery box as is (per googling some measurements) would kinda fit in the bed initially (a little wide, so might need to sit on top of the wheel wells and be otherwise supported)
3. Or would I need to be looking at something like a Tesla motor?
4. I'm assuming the mechanical challenge with the Leaf would be mating the motor with the transmission?
5. Is there another obvious clear best path forward as far as motor and related parts selection goes?
6. I'd probably need to upgrade the brakes right?
7. Likewise with power steering?

Appreciate any feedback!

 

[eg0n]

Thanks for the feedback, Tremelune. Totally understand that even a kit conversion is a big project, especially for someone who's not skilled in this area already. I'm in it for the project and learning experience as much as the end result. I'll think more about doing a bug first (also, realistically, if I find it's really not for me, a bug with a partially installed EV West kit is probably a much easier flip than a pile of parts and a gutted Scout).

Another route would be to use Chevy Bolt batteries and a Hyper9 or some such. Adaptation would be a lot easier, and the batteries are much better, but you're looking at $20k minues what you could recoup form selling the rest of the Bolt.

A quick google tells me the Bolt battery packs are 66kWh vs Leaf's 42-62, is that the main difference? I also notice the whole Bolt battery pack is heavier.

Is there likely to be much difference in difficulty/level of customization required to do a full part swap from a Bolt vs Leaf? Is the Leaf just advantageous due to the big used market?

I wouldn't mess with the brakes or steering until it seems necessary. With regen, you won't use the brakes much at all, and heavy steering has a lot more to do with tires and castor than weight. The torque from the average electric motor will be more than stock.

Gotcha. My only concern was safety on the brakes. I'm guessing though on a truck they'd be already be sufficient for whatever load it's rated for on top of the weight of the vehicle?

 

[eg0n]

Right, that makes sense. Appreciate the input. I'll do some more reading with all that in mind.

 

[eg0n]

For what it's worth, I started this process having never done anything with cars. Not even changing the oil. But with hands-on experience, I have learned loads about everything related to engines than I thought was possible.

That's awesome. The more I read the more I think I can do it, just need to take my time. I'm definitely expecting it to be a 6-12mo project.

I'm going to echo what Tremelune is saying here. The leaf motor would be more than enough power to get to 75 mph IF you use a gearbox, which I highly recommend. The only challenging bits of the leaf are adapter plates for adapting it to the transmission and the voltage. Nissan leaf inverters require 300-400 volts I believe for full performance (although they will spin with less), which is why I'm not going to use a leaf motor in my conversion, since I need at least 140-150 miles of range and I am using tesla modules for their energy density. If you are going to use a leaf motor, I would just buy an entire salvage leaf (<$10k) and pull the motor and battery pack from it. The leaf motor has a fixed differential bolted on but that can be easily removed if you want to mate it to a manual transmission. This option is the cheapest and would definitely be a good choice.

Another option is to go with a Netgain Hyper9 HV motor, which is a motor designed specifically for conversions. They're $4300 for the motor, inverter, and contactor. You can pair that with 7 Tesla modules ($1000 each about) for 35kwh of battery capacity. This should give you at least 80 or so miles of range, and driving conservatively I'd guess you would get over 100 easily. A total for this option would be somewhere around $20k.

So if I used the components from a Leaf I'd have to use the battery setup in pretty much its exact existing configuration if I wanted to use the Leaf BMS right?

I'm not too concerned about perf, and 75 top speed is probably fine for me, but if I wanted to increase the range to more like 150mi (maybe even 200mi) what would I be looking at? A full set of 14 Tesla battery modules? Is a full Bolt pack likely to meet that requirement with a Hyper9?

I'm still a bit undecided about the requirements. I know what my bare min requirements are, but if I end up spending more on a really nice example of a Scout it seems silly to not go all out on the conversion. I don't have a hard budget requirement, just what I feel like I want to put into it.

 

[eg0n]

I'm attempting something very similar with a Bronco, but I'm removing the engine, transmission, and transfer case and replacing them with a Tesla large drive unit mounted at an angle to drive the front and rear axles. I'll gain some efficiency by not running the motor through a gearbox but then I'll lose some by it being full-time four wheel drive, so it may end up being a wash efficiency wise. Mostly I'm doing it this way so I can have more room for batteries.

So far this is what I've purchased:

Tesla LDU with drive shafts and wiring harness - $2400
Quaife 4.5 gearset - $2600 (ouch, I know)

I plan on using the EV Controls drive unit controller - $2700

AEM has also just released a Tesla drive unit controller for about the same price but the EV Controls unit lets you view and change settings in real time with an ipad, so I wont have to buy further instrumentation to gather data.

So right now the damage is $7700 and I still need batteries, BMS, charger, DC-DC converter, accelerator pedal, and a precharge circuit. Plus motor/battery cooling and custom driveshafts.

Overall I think my price and range goals line up with your project but I may end up with less range unless I can find a killer deal on batteries.

Keep us posted! I'd love to see what direction you decide to go.

This is an awesome design. So you're gonna basically fill the engine bay with batteries?

I understand a lot more about how the 4wd components work now. I'd probably lose a reasonable amount of efficiency in 4wd yeah? I'd consider pulling out the transmission and transfer case for efficiency but I guess that would be a lot of fabrication work like your project, which might be a bit out of my league for now.

 

[eg0n]

I agree with reider, the Netgain option has been used by a lot of companies like EV West and ElectricGT so there's already a lot of adapter options and application examples out there for reference.

Since the Scout and the Bronco are about the same size, I think it's relevant to mention the amount of real estate available for batteries. It's probably possible to fit 10 or even 14 Tesla modules in the Scout, but it will require a lot of fab work and Tetris-ing to pack them out of sight. But, if you are not worried about putting them in the bed then it gets a lot easier.

For reference, the Bronco kit sold by ElectricGT keeps the transmission and transfer case and has 65kWh distributed between the fuel tank area, the engine bay, and the space under the seats. I think that's about the max amount of batteries that can be packed out of sight in a Bronco or Scout-sized vehicle if you keep the transmission and transfer case. That should get you about 130 miles of range.

That's a useful data point, thanks. I'll have to read more on what has been done on similar vehicles. I'm fine with batteries taking up the entire bed to begin with, and I'd likely look at improving that over time. I'm currently feeling out if my friends who work at Tesla can get me any sweet deals on batteries 😇

 

[eg0n]

If by "existing configuration" you mean 96 sets of cells in series, then likely yes. On the other hand, other than the length of wiring between BMS components and battery modules, the physical arrangement how the modules are stacked up and packaged) doesn't matter to the BMS.

Yeah, I meant if I wanted to use only part of the whole Leaf pack for whatever reason (or additional sets of cells if the other components could handle it) then I'd need a more flexible BMS. Is that correct?

 

[eg0n]

Decided to go with a Scout 800. Rolled this bad boy off the truck this week. First order of business is to clean off all the 🐦 and get it running so I can at least drive it in the interim and don't just let it sit and rust while I faff about being indecisive about the project direction. Pretty good condition overall - most Scouts of this age are well-rusted.

 

[eg0n]

Keen to see your cruiser build too, all the rich kids parents had those when I was a teenager in Australia 😂

-Maintain the stock transfer case but ditch the transmission. It's possible you can find a "doubler" that matches your transfer case. Doublers are used to ultra-low gearing on 4x4 trucks with massive tires and basically "double" the reduction ratio into the transfer case. This is what you want in order to direct drive with the LEAF motor because you can ditch the transmission's dead weight and better utilize the transmission tunnel space possibly even fit the motor there and have an entire engine bay for batteries.

I thought about this but I talked myself out of it. I wasn't sure how to go about the gear reduction and didn't realize there were good options out there. How do I go about calculating what gear ratio I would need? Are there generic options that would do what I want? Would be amazing if I could fit the whole motor and gearbox assembly further back to make room for batteries. The only down side is I do like the idea of being able to slam on the clutch as a safety measure

-Keep the stock transfer case so you can shift to Low Range and go offroading or pull trains or whatever sounds most fun to you.

Yeah def keen to do this!

-From my experience driving EVs I expect my 4x4 EV to get 2mi/kwh on a good day. That means to go 100 miles, it needs 50kwh of usable capacity. Something to think about. I plan to use a single LEAF battery to start, and then add more as I go because they are the cheapest option. I do not even know if multiple BMSs can be run independently like that but I think they can.

Yeah I think if I decide on the Leaf part swap I'd just use whatever pack I got with the donor vehicle and explore other battery options later - maybe flip the whole leaf pack and BMS

-Download the CAD file for the adapter plate and wait until the coupler adapter is available for purchase here: For Sale: em57 leaf motor couplers then just need to have a driveshaft shop build a custom shaft to match and build some motor mounts!

THIS is what I've been looking for. So what exactly would I need to connect this coupler to the gearbox/doubler?

 

[eg0n]

Ah this is helpful, thanks folks. I appreciate the fundamentals because I'm pretty new to this aspect (I mean, and all aspects of how cars actually work). So, I need to get underneath and confirm exactly what I have on this truck but say the rear axle is a Dana 44 with a gear ratio of 3.71, and I'm using 235/75R15 tires with a 130km/hr top speed as in Brian's example:

Tire circumference is 2304mm, so 1 rotation is 2304mm.
Speed in m/min: 130 * 1000 / 60 = 2167m/min
RPM at the axle going 130km/hr: 2167 / 2.304 = 940RPM (this is slightly off from your example Brian, did I do this wrong?)

Driveshaft RPM: 940 * 3.71 = 3487

Maximum ratio: 10500 / 3487 = 3.0

So 3:1 gear reduction. Does that seem about right?

Use that ratio or less (taller gearing) so that the motor never goes too fast; the higher ratio (shorter gearing) that you use, the more torque you have to the wheels at low speed, and the lower the speed where you start into getting full motor power available.

Reading this it sounds like ideally I want to be as close to that maximum ratio as possible, without going over. Is that right?

 

[eg0n]

You would need to have a custom driveshaft built. Also that coupler is only halfway made, it's designed to be drilled out to bolt on a specific drive coupling but instead of that my plan was to have a machine shop weld or bolt on a common sized driveshaft yoke.

Gotcha, so I'd need a custom driveshaft with this coupler bolted/welded to one side, that can bolt onto the input shaft of the doubler on the other side.

 

[eg0n]

What are the considerations for a minimum reduction ratio? Amount of torque available from the motor at the low RPM end?

I'm wondering if I could just skip the doubler and mate the motor directly with the Dana 20 t-case already in the Scout and run it in its 2:1 mode. Obviously wouldn't provide any higher reduction if I wanted to actually use it for crawling or anything, but that's not a primary goal. Thoughts?

 

[eg0n]

Thanks Brian, I'll explore those caveats.

 

[eg0n]

Thanks for the detailed analysis, Brian. Sounds like leaving the Dana 20 in low range isn't a great plan. It seems like the best path forward is either finding/building a 2.5-3:1ish doubler or just proceeding with the original plan of retaining the transmission and clutch. I've read a bit about building doublers from other transfer cases and I'll do some more investigation. I'm not sure it's worth the weight reduction if I have to spend multiple thousands on a special purpose doubler, but if there's the possibility of building something out of a common transfer case then it might be worthwhile.

 

[eg0n]

Quick update: Got the 152 running well, done the shocks, brakes, shoes and put some Corbeau seats in. Decided to go the Leaf swap route. Coupler for the Leaf em57 motor is en route courtesy of user Bratitude, and I’m on the hunt for a salvage Leaf. Hopefully will have a breaking down the Leaf update soon!

 

[eg0n]

Hey folks, I’d like to get some feedback on my current plan. As I mentioned above I’ve got my Scout up and running and I’m ready to buy a Leaf to cannibalize.

I’m planning to buy a whole salvage Nissan Leaf >2014, preferably with the Plus trim for the 62kWh battery. I’ll use the following components from the Leaf in my build: motor, inverter, battery pack, BMS, contactor/precharge circuit, PDM (slow and fast chargers, DC-DC), with an aftermarket controller.

After some discussion with the folks from Thunderstruck and Resolve-EV I think Resolve is the better option for the controller (though I’m open to input here). Their focus seems to be more on full vehicle swaps rather than just running the motor and inverter. They support comms managing the PDM, and say it should work with the gen3 battery pack with a little additional reverse engineering.

I’ve got a coupler on the way from user Bratitude. After chatting to them I think a clutchless design is going to be the way to go. My desire to retain the clutch was primarily to have a simple mechanical way to disengage the motor in an emergency (I work on software security for a living - I don’t trust software), but Bratitude pointed out that I can just pull the stick into neutral in that case. I’m not too concerned about shifting as I should be able to get close to top speed in 2nd (tho I need to do the accurate math on the gear ratios here), and it’s not expected to be a speed demon anyway. I’m sure I’ll figure out clutchless shifting. Bratitude also suggested an electrical cutoff on the PWM input to the motor controller (similar to Brian’s suggestion upthread). So I think between these I’m pretty satisfied with the non-software safety aspects with a clutchless design.

The motor and transmission will be joined directly by the coupler, with an aluminium adapter plate mating the transmission bellhousing to the motor (I'll likely buy one from user: Electric Land Cruiser over here once I figure out if that will have enough metal to mate with the bellhousing on the Scout's trans, otherwise I’ll have one fabbed).

The coupler has internal splines for the Leaf output shaft on one side, and blank metal on the other. My options are:

• Find a machine shop that can mill internal splines matching the Scout’s transmission
• Cut down a clutch disc and weld it onto the end (this seems super janky and tough to get right)
• Find some other hub that matches the scout trans spline and attach it somehow?

For my initial proof-of-concept the whole Leaf battery pack will sit in the tray of the Scout, and I’ll figure out where they can go once I get everything going. I’d like to have a rear seat, so there’s a few options for batteries:

1. Under the hood
2. On top of the long, flat wheel wells that span the entire length of the tray
3. Behind the rear seat
4. Under the rear seat

Between 2, 3 and maybe 4 I can possibly fit the whole broken down pack without needing multiple BMSes. We’ll see when I get there.

Concerns, challenges and opens:

1. Best way to get the Scout trans connected to the coupler
2. Unknowns with using the 62kWh battery
3. If I get a gen3 Leaf, the Resolve folks haven't had much experience there yet so I might be doing a bit of reverse engineering of the BMS comms. I'm comfortable with that, but it's something that's going to add some time. From chatting with Isak I think I'll probably have some support getting it to work, and I'll gladly feed back information from my own reversing. Alternatively I can focus on getting a gen2 Leaf with low miles, but it’s somewhat dependent on what I can find.
4. I believe the Leaf inverter and PDM require liquid cooling

Any feedback? I’m particularly interested in any huge flaws in my reasoning, or big things I might have missed that I need to make a decision on before I commit to this plan, and definitely experienced input on the best way to approach the coupler situation -- bladesmithing experience has not prepared me for designing things involving real torque.

The next steps for me are:

1. Buy a leaf and strip it down
2. Decide on and buy a controller
3. Get the motor/inverter/batteries/basic charging running on the bench with the new controller
4. Pull the transmission out of the Scout (the point of no return [not really, but the Scout will sit in the carport until it's drivable from here, unless I buy another transmission or something])
5. Get the coupler machined to fit the Scout trans
6. Buy or get an adapter plate made
7. Get the motor and trans mated on the bench
8. Put it all together

Then it's phase 2: polish. Stashing batteries and figuring out whether I need another BMS, getting fast charging working, instrument panel, etc. At some point in there when it makes sense I'm probably gonna have the Scout painted (frame off), clean up and POR-15 the axles, etc. I'm loath to strip it all back down once it's built, but I also don't wanna get sidetracked with general restoration stuff and focus on the EV conversion. I also don't wanna have a nicely painted and restored Scout body that I then have to cut up to fit stuff into, so we'll see. There's some other stuff I wanna do like disc brake conversion, maybe improve the steering, etc. But that can probably come later. Anyway, lmk what you reckon! Thanks, as always for the collective wisdom!

 

[eg0n]

Good advice -- I'll do some more research and check the dimensions before I go with the 62kWh battery.

 

[eg0n]

Gen2 battery is significantly smaller, but I don't think it will get you to the desired range with the boxy aerodynamics of this vehicle. Leaf itself can barely make the range. Though of course I don't think you specifically stated at what speeds you're planning to commute for that distance.

Yeah I didn't really factor the increased pack size in. The 24kWh pack will (just) fit unmodified in the back, but I'll have to find some dimensions on the 62kWh one.

 

[eg0n]

Re: the range, 55-65mph top speed but it's hilly so probably not gonna get that range. I can charge at both ends. Honestly I'm less concerned now about commuting in it - it'll probably be a fun local runabout in the end. I forgot how rough old trucks are 😂

 

[eg0n]

Looks like the new packs are actually about the same size. Slightly taller, some lumps and bumps (e.g. BMS on top) and a lot less free space inside the case.