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Discussion Starter · #1 ·
Hello all...110% new to the forum and EV cars in general. SO much good stuff to read on here!

Ive had a lot of experience building several IC cars, but want to dive in head first with an EV conversion. In general my mechanical skill level is good, my electrical level not so much (insert mechanical vs electrical engineer jokes here). I'm considering two options, keeping the standard gearbox or getting rid of it and mating the motor directly to the transfer case.

Ive selected a Defender 90 as a conversion vehicle for a few reasons, the body on frame construction helps a lot in the ease of installation of motor, battery brackets etc. even though aerodynamic and drivetrain efficiency are laughable. A large part of it is practicality from a cargo/hose down point of view.

That being said the range I'm looking for isn't huge. This will be mainly my wife's car to commute 50 miles round trip every day in mixed stop and go and 70 mph traffic. So ideally 100 mile range (excuse my ignorance if this is wildly unrealistic).

Performance wise anything that is an improvement on the standard 122 hp (91 kW) / 221 lb⋅ft (300 N⋅m) diesel engine would be welcome.

This is where things get sticky. I haven't selected any components yet, but have read several of the Wiki articles. The 4 steps in sizing a battery seem to me to be excellent if working with a lot of known variables. But...since the existing diesel power of the vehicle is already known, and this takes the vehicle to top speed and gives a certain acceleration, can this not be used as a basis and work backwards from there to reach a needed battery power and energy?

Naturally at a steady cruise speed not all of the diesels 91kW are being used, only a fraction of that. So if anything, in my mind choosing a 91kW motor would give increased performance, albeit a battery to go with it would be unnecessarily large for 100 miles of range. Or just plain not fit in the available packaging space of a Defender 90.

In the end is that a good starting point or not even close?
 

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Discussion Starter · #3 ·
Right...an important part.Well, as I'm very unfamiliar with the topic and don't know exactly what size motor/battery Ill need I'm a bit in the dark. That being said going from other conversions Ive seen I know I'm not up to spending Tesla motor money, but neither do I want to go with a forklift motor. So for an AC motor and parts Id guess it'd be in the 10-16k US dollar range.

Unfortunately this project will take shape in the UK, so there would be the matter of importing or sourcing here. But I haven't so far seen prices for parts sourced directly in the UK. I know this is just because I haven't looked around enough though...
 

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Discussion Starter · #5 ·
Hi Kevin

Those are all very helpful...thanks!

I had seen that Defender you sent but havent seen any project details so far. Interesting to know it uses a Leaf motor...it certainly looks like it moves it along quite well!

What other options would there be as far as aftermarket? Im thinking more in the sense of future support, upgrade-ability or even if the first one works out making a second conversion.

Im still very curious though about the correlation between the existing diesel and choosing an electric motor to replace it.
 

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Discussion Starter · #8 · (Edited)
Thanks Dave, Kevin...excellent info. I didn't think the Leaf stuff would be as inexpensive. That being said it did give that Defender 100 very good acceleration! I'm now curious about cruising speed/range with that motor and how many batteries it would take to get to the 100 mile range goal.

I'm still curious about the correlation/conversion factor between an IC engine and an electric motor. Even if just for my own information as for the Defender in particular there's already the Leaf powered one which does very well.
 

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Discussion Starter · #11 ·
Given the Leaf curb weight is 3,300lbs, it's pretty aerodynamic, and has an EPA range of 84 miles (24kWh battery), I think you should assume you'll need ~48kWh for a real world 100 miles range, given the weight and aerodynamics of the Defender.

I've attached a Leaf range chart estimator :cool:

Cool...thanks for that!
 

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Discussion Starter · #12 ·
I think Kevins about right on the kWh estimate. The electric classic Range Rover that Electric Classic Cars built last year was 80kWh and had a max range of 200 miles, so I would have thought that 48kWh should be good for 100 mile range. The weight, aerodynamics and parasitic load of the drivetrain in a Defender are all against you though. When I picked up my Tesla Model S batteries off ECC a few weeks back the main guy there took me out for a spin in his mental Beetle, which had 48kWh too. He said it would get 200 mile range at a push but it's probably half the weight of a Defender.

Whats the plan? are you going to attached a motor to the gearbox via an adapter plate or direct drive it?
Looking at the Leaf battery pack as an example it looks like this to me...

24kWh = 48 modules
48kWh = 96 modules

Lets round up to 100 modules just for the math...50kWh, each module is 303 x 223 x 55 mm then a battery pack of 100 modules (only modules no other hardware) split into 4 stacks of 25 modules would be a box of 606 x x446 x 1375 mm. Is that math making sense? If so splitting that box into two taking up the space where the fuel tank used to be and on top of the motor at the front looks to be totally doable.

As for the motor attachment plan there's two options, attached to the gearbox or dump the gearbox and attach it to the transfer case. If they would have made 2 wheels drive Defenders with IFS then Id consider direct drive. But doing that on the Defender would make the front axle completely useless. I think the gearbox attachment route would be best as it gives the option of the 5 gears to play with.
 

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Discussion Starter · #17 ·
some time ago I done some calculations for my friend as he wanted to convert it to electric, we discussed about an option to use leaf motor and connect it to central diff (it have 2 speeds, low and high, as I know) so you get couple possible reductions to wheels and can place motor in gearbox place.
unfortunately my friend went to a different car, so not done defender project...

That's only sort of accurate though. Yes, it does have 2 speeds, but only in 4WD, and the Defender 4WD system can not be used on asphalt as it doesn't have a central differential. In 2WD its only 1 speed. The only reason to connect it directly to the transfer case is to lose the gearbox.
 

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Discussion Starter · #19 ·
Well, no mass-production pure battery electric cars have a multi-speed gearbox, since the original Tesla Roadster transaxle failed and is long gone, the Rimac cars are nearly custom exotics, the cars using GKN's two-speed eTwinsterX are all hybrids, and no one is currently using any of the several available two-speed transaxles intended for electric drive in production.

I agree that with a modern motor (not so much for a forklift motor) only one ratio is needed, and that's the current normal practice.

I also agree that
  • you likely need some gear reduction between the motor and the final drive, and the stock transmission may be the cheapest and easiest (although not lightest or most compact) way to get it, and
  • you may not know the best gear ratio in advance, and shifting the stock transmission is an effective way to change ratios.

Yes, that's true that no current EVs have a gearbox...this would only be for simplicity sake. That being said though, would there not be a benefit to keep the electric motor in a certain RPM range to extend the battery life? Or is that completely irrelevant for electric motors, and they use the same amount of power regardless at what RPM they're running at?

The other option which I forgot to mention is getting rid of the gearbox, and replacing it with a 2 speed over drive unit which would give 2 speeds.
 

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Discussion Starter · #20 ·
I think attaching the motor directly to the transfer box and placing it where the gearbox is would free up a lot of space in the engine bay for batteries. Although you'd need to do all the calculations on ratios, both transfer box and diff to see what rpm vs road speed gives you. This page I've just Googled might help.

If I remember rightly the ECC guys were going both ways, one Defender was having the motor attached to the gearbox the other was going to be direct drive. I'm not sure why they're trying both routes, maybe to see which works best, more than that you'd need to ask them. My thinking is that if you're planning on going serious off roading or towing you should keep the gearbox, if it's simply going to be on road then direct drive or through the transfer box could be a viable option, as long as all the ratios are in your favour.
Thanks for that...Ill have a look at the ratio calculator and input a chosen motor in there to see the rpm/speed it would give.

This would be 99% for onroad driving, and getting rid of the gearbox and just connecting it to the transfer case would be the easiest/neatest installation. Direct drive isn't really an option though as it would render the front solid axle useless and way overkill to just do the suspension/steering work. For a direct drive the ideal thing is a 2WD pick up, or an SUV that is sold both in 2WD and 4WD versions like a Toyota 4Runner.
 

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Discussion Starter · #24 ·
??? Defenders are permanent 4x4, and can be used on asphalt. There is no 2WD option for a Defender. I think the Series 3 Land Rover had selectable 2WD/4WD though.

Yes duh...sorry, forgot to engage brain before writing! I was thinking the older style Toyota/Jeep transfer cases.
 

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Discussion Starter · #25 ·
I agree, Defenders are permanent AWD. Only hi & low ratios. I'd recommend trying to lose the AWD completely and go directly rwd. Either use the transfer box for 2 speeds and lock/weld the diff without a front drive shaft or if you can get a crawler crown & pinion ratio (or swop to a different axle with crawler ratio like a Dyna) go directly to the axle. Only trick then is running an empty front axle or swapping to a solid beam?
Personally it's alot of work but I'd build a custom independent suspension subframe for the front and also the rear and mount entire leaf motor into subframe in the rear. You could pack all battery into the engine bay in a nice brick/block of cells easily removable.
Whatever way it has potential to be a brilliant conversion.
Yeah...this would be waaayyy beyond the scope of this project. This is meant to be a straight forward electric conversion, not a complete redesign of suspension systems etc etc

If I were to go this route Id do something different. Im working on a few small bits and pieces for my other "project car", a 73 Firebird, and one of those is working with a metal shaping guy (http://www.chris-isaacs.com) who also does customs chassis work so a completely new chassis with IFS and only rear wheel drive would be the ticket! Some other time :D
 

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Discussion Starter · #26 ·
I'm pretty sure the ECC direct drive Defender was keeping it's 4x4, but to be 100% you'd have to ask them.

Talking about steering above, whats the plan there? obviously it will need power steering but you're going to loose the pump when the engine goes. Are you going to convert it to EPAS?
There is a company doing EPAS for classic cars...that may be an option. Ideally Id love a front driven accessory plate like the one EV West does which includes the AC compressor and such. I'm still on the fence about this one. There's also electric power steering pumps...that might be the most straight forward solution.
 

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Discussion Starter · #36 ·
I agree with Brian, I can't see how an accesory plate thing would work with a power steering pump. Surely when you need it most is at very low speeds, but then the motor wouldn't be turning enough to make the power steering pump work.

Also, I'd be surprised if the companies that make EPAS solutions for classic cars have a Defender kit. The reason being that they usually make kits for classic cars that didn't originally have power steering. Making a kit for a car that originally had power steering would be a very VERY small market for them :D Maybe they can sell a generic kit that you can fit to any car, although it would need to be powerful enough to deal with the Defender's steering torque which is huge. I'd be wary of getting one off a production car that has EPAS like a Vauxhall as it might not have the grunt for the Defender application.
Th EPAS company Im thinking about (cant recall their name right now) doesnt make set EPAS for each classic, they do more of a retrofit to any type of steering column type of thing. So their system would definitively work on a Defender. Essentially its custom made.
 

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Discussion Starter · #37 ·
Been away just caught up with this. Following with intrest

Ive been building / modifying LR for 35 years

Defenders don't have rack & pinion steering have a PAS steering box . I would not even bother I have armstrong steering in mine & its a non issue.



If you do there is no problem putting an RRC column in a Defender , Ive done it in a RRC/ Series hybrid , Defer steering wheel even fits.

This is my Electric LandRover www.goingbush.com/ptev.html

If you want to ditch the constant 4x4 ( I'd keep it) Santana PS10 / Iveco Massif have a 2WD /4WD version of the LT230 transfer case , it will bolt straight in.

or Ashcroft have a 2wd/4WD kit for your LT230

http://www.ashcroft-transmissions.co.uk/miscellaneous/part-time-4wd-kits.html
Thanks for that info! Id definitively leave the stock transfer case...no need to add additional complexity.

On a side note...Ive seen your videos a while ago. Excellent build! My wife actually originally wanted something similar to your lightweight but the UK weather doesnt much lend itself to driving a Land Rover with a canvas roof year round... Its a sham because of all the cars Iv oned one of my all time favorites was a Jeep CJ8/Scrambler (I know, I said the J word) which only had a bikini top pretty much year round. Then again that was in Florida...

Oh and yes, no rack and pinion, but an electric pump to power the stock steering box should work just fine.
 

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Discussion Starter · #42 ·
Right, and that's my point...I'm not going to get involved with CAN signals to vary pump assistance etc etc...this has to be a conversion with as few variables as possible, and the ones that are inevitable have to be as simple as possible as well.

In any case...I think there's several options for power steering. First things first, motor and battery selection.
 

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Discussion Starter · #43 ·
So battery wise I think I will go down the Leaf route. Theyre available, have all the hardware to connect them, and are not too expensive. I need to check the volume where Ill put them (fuel tank position, and on top of the motor, maybe even along driveshaft). If there is enough space I will try to go with the initial calculation of 100 modules.

The motor I need to select. Im leaning towards connecting it directly to the transfer case though and getting rid of the gear box.
 
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