Electric Motors

[finnarne]

As far as total power and torque required, the BMW M51 in the diesel P38 has 141hp / 105kW and 210lb/ft / 280Nm - that would be acceptable, especially as the torque curve for an electric motor is much better than the M51 so it would address the diesels main shortcoming (massive turbo lag from stanging). The 4.6RV8 has 225hp / 168kW and 280lb/ft / 380Nm, which would obviously be nicer!

Golden motor specifies their motor.

They have a 20kw BLDC motor which could maybe be used if you add 2 motors.

I have a 5kw motor in my sailboat, that I installed late last year, but did not get around to test it before winter came.

I've been thinking about adding 2 electrical motors to the LT230 transfer case.

With a rated power of 20-25 kw, and peak of 50kw , togethger with 80Nm rated torque /160 Nm peak Torque, if the numbers would double if 2 engines was instaled, then maybe it would be sufficient.

It would definitly would be a funny project.

[geoffbeaumont]

You'd definitely want to run via the gearbox, though - even with two of them you're at 320Nm peak torque (so the same as a 4.0 RV8) - so cost permitting it would make more sense to source a single more powerful motor (easier to install - probably more efficient too?). Bear in mind with 200Nm in a Freelander (1.5ton vs 2.5ton) Si felt it really needed a multi-ratio gearbox.

Interestingly one of their examples is an axle differential mounting (half way down here: http://www.goldenmotor.com/eCar/frame-eCar.htm) - it looks quite bulky, but that appears to be quite a small axle scaling from the motor.

[simonr]

You said above (ish correctly) that because electric motors have a different power curve to an IC engine, you can get away with a lower power motor. This is true for Power, but not torque.

Electric motors (in general) have a flat power curve with max torque at 0 rpm and 0 torque at max rpm. That's ideal for pulling away and the main reason you can get away without a gearbox, so long as your peak rpm is high enough to give you a decent top speed - and the torque is high enough to perform a hill start. A given power of motor will give you similar 'performance' to an IC engine with double the power - but it still needs enough torque to pull away. Often the only way you can achieve that is to gear it down.

Si

[Bowie69]

Sounds like a good application for a CVT transmission...?

[geoffbeaumont]

On the torque front my understanding was that (particularly with respect to things like off-road driving) the availability of maximum torque from 0rpm made a significant difference (i.e. in many situations you aren't actually using the maximum torque of the ICE because it delivers that further up the curve). Obviously makes more difference if you're talking about a rev-happy engine than the sort of things we have in Land Rovers. Or does that not actually make much difference in practice?

In any case, I was working on the basis that I needed to deliver as much torque at the wheel as the standard drivetrain as a sensible target.

[geoffbeaumont]

Sounds like a good application for a CVT transmission...?

That thought had occurred to me. Not so sure where to find one that's man enough for the job though.

[Bowie69]

Audi V8

[Bowie69]

...or... use a GKN overdrive/some other planetary gearbox to give two ratios at a push of a button?

[cackshifter]

The other thing about electrics (which I don't think has been mentioned) is that they have different ratings according to the duration they have deliver power for. So normally an electric motor would be continuously rated, but it might have a higher half hour rating for example, depending on the insulation class etc when in effect you are temporarily overloading it( a starter or winch motor being prime examples of this). Some will only be rated for momentary use. You can't do that with a normal ICE (Ok overboost and nitrous exists) . But suppose you thought it would be good as a wild example to drive electrically through the PTO connection,to supplement an ICE for say very low speed, or to assist hill starts, you might not need more than a few minutes' running, and a much smaller motor would suffice. In effect they are rated more round the average demand whereas ICE is more towards the peak.

[Superpants]

I don't know how you are set budget wise, but the current state of the art in EV motors that you can buy off the shelf are GKN/Evo and Yasa:

http://www.gkn.com/driveline/our-solutions/edrive-systems/eMachines/Pages/default.aspx

http://www.yasamotors.com/

These are the types of motors being widely used in electric sports cars, vans etc. There are other alternatives, but you'd certainley get the right sort of performance out of them.

As Si has pointed out DIYelectriccar is a good source of info, as is the endless sphere forum- as might be expected there is always a load of politics going on between posters!

[simonr]

The Yasa motors are nice - though they have a very spendy look about them! I may have to wait for the Britpart version before I can afford one!

Si

[FridgeFreezer]

...or... use a GKN overdrive/some other planetary gearbox to give two ratios at a push of a button?

I'd have thought that would be preferable - with an electric vehicle you want to minimise losses, so auto-boxes etc. would seem like a bad choice. A single planetary gearset that can be simply & instantly dis/engaged would give you a basic reduction set for starting off without too much extra size/weight/complexity.

A G-wagen transfer case could do as (if you believe Dirtydiesel) they're 2:1 ratio & have synchromesh (!) on hi/low switching.

[Daan]

I Hate to sound negative, but a P38 is potentially the worst starting point for an electric car. heavy, big frontal area, 4wd, it al works against a decent mileage on a battery charge.

Have you looked at batteries? a decent lithium ion pack costs a fortune, and usually, most electric car projects (professional or DIY) die an early death at the point that the battery pack is considered. It is either the end of a potential project, or the point at compromises are made on price, and the great mileage that was being planned vanished, which usually also takes the chances of success with it. I have looked at an electric car myself, based on a citroen AX (lightest I could find), and using a diff into a yasa motor. It didn't quite work out on torque for hills, so ideally you'd need 2 yasa's, one for each wheel. The problem with doing it properly is as usual money: The yasa was 5k at the time, and I worked on 5k for a battery with battery management system. it would work out at 10-15k on the battery and motor(s), and I hadn't even though about a controller, plus many other things. Any motor that is not permanent magnet has bad efficiency figures, and anything not lithium ion is pretty much not a goer in my opinion. For me to have an electric car, I would need at least 60 miles range to commute, maybe less if I can charge at my employer.

If you plan to spend that kind of money, maybe a Toyota prius is a better bet, and swap the engine for a larger battery pack. I went conventional and bought a polo bluemotion instead. Then the fuel prices reduced massively and I spend pennies on fuel.

[geoffbeaumont]

The other thing about electrics (which I don't think has been mentioned) is that they have different ratings according to the duration they have deliver power for. So normally an electric motor would be continuously rated, but it might have a higher half hour rating for example, depending on the insulation class etc when in effect you are temporarily overloading it( a starter or winch motor being prime examples of this). Some will only be rated for momentary use. You can't do that with a normal ICE (Ok overboost and nitrous exists) . But suppose you thought it would be good as a wild example to drive electrically through the PTO connection,to supplement an ICE for say very low speed, or to assist hill starts, you might not need more than a few minutes' running, and a much smaller motor would suffice. In effect they are rated more round the average demand whereas ICE is more towards the peak.

I think the figures everyone has been using above (certainly the ones I have) are peak torque, not continuous - even if you can only use peak torque for less than a minute that should be plenty in an automotive application where torque demand is very peaky.

[geoffbeaumont]

I'd have thought that would be preferable - with an electric vehicle you want to minimise losses, so auto-boxes etc. would seem like a bad choice.

You can say that about any vehicle, though!

[geoffbeaumont]

I don't know how you are set budget wise, but the current state of the art in EV motors that you can buy off the shelf are GKN/Evo and Yasa:

http://www.gkn.com/driveline/our-solutions/edrive-systems/eMachines/Pages/default.aspx

http://www.yasamotors.com/

These are the types of motors being widely used in electric sports cars, vans etc. There are other alternatives, but you'd certainley get the right sort of performance out of them.

As Si has pointed out DIYelectriccar is a good source of info, as is the endless sphere forum- as might be expected there is always a load of politics going on between posters!

Probably the tastiest looking one I can see at a quite glance there is this:

http://www.gkn.com/driveline/our-solutions/edrive-systems/Documents/Datasheets/AF-240-Tech-Sheet-V14.pdf

Good balance of torque and rev range. Can't see any prices on the web...

[geoffbeaumont]

I Hate to sound negative, but a P38 is potentially the worst starting point for an electric car. heavy, big frontal area, 4wd, it al works against a decent mileage on a battery charge.

See my first post!

So far it's a purely paper exercise, so I'm being idealistic and ignoring budget. If I actually build it then budget will come into play and (major) compromises will have to be made. I'm quite well aware that enough batteries to give a decent range are likely to be exorbitantly expensive (even from an idealistic point of view, I'm considering a small ICE in a range extended electric setup - but no point worrying about that until I've figured out a workable drive solution).

I quite agree that it makes no sense economically - but given that I work from home and my transport needs are adequately covered without having my own car at all no car really makes economic sense. I've never owned a Land Rover that made economic sense - but I've had a lot of fun tinkering with them

PS. Worst is a bit harsh - I could start from an L322...

[Daan]

It almost sounds like a vapour build! I think the yasa boys would sell you a motor, but potentially EVO (or GKN) wouldn't. They are only interested in triple figures. I know this, as I worked for GKN hybrid power for a bit, that uses EVO motors.

One motor supplier to consider is lynchmotors.co.uk. Not quite the power of a yasa, but if multiple motors float your boat, certainly worth a look.

[honitonhobbit]

Geoff, if you pootle up the M5 to J23, next door to the British Car Auctions is Causeway 4x4, part of the Lloyd Ash Group. They are one of the market leaders in Gas conversions but are now moving over to electric upgrades in classic sports cars... Nice people

[Yostumpy]

I'm sure you've all seen this before, Good fun, skip #3 tho'

http://api.viglink.com/api/click?format=go&jsonp=vglnk_145831846015313&key=36ad8bc22d612b2ca8645f59506d611a&libId=ilxw3pdt01001ld0000DA4icbndw5&loc=http%3A%2F%2Fwww.pirate4x4.com%2Fforum%2Fgeneral-4x4-discussion%2F731478-electric-land-rover-defender.html&v=1&out=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DlSV_46y6ufs&ref=https%3A%2F%2Fwww.google.co.uk%2F&title=Electric%20Land%20Rover%20Defender%20-%20Pirate4x4.Com%20%3A%204x4%20and%20Off-Road%20Forum&txt=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DlSV_46y6ufs

[The Badger]

I been toying with this idea too, one issues is also the weight distribution, one thought was to go through the transfer box, but so you get one big motor where the gear box is, or two on different gears.

I thought to remove the transfer box, but then all the weight is slightly on the right, using two big motors and a shorter prop on the back to give more space, for the gearing I though to change the gear ratio of the diffs.

On a weight nite, a tesla is about 2tonne, my 110 with are ARB bumper on/winch, roof rack, 120litre fuel tank with side 40litre, then two 40 liter tanks under the doors and afew more bits was all in 2.6tonnes.

So, even if I strip all that out could I even get a 110 to be 2tonne, with EV motor and batteries? Unloaded?

[Daan]

Some of the answers here:

http://www.greencarreports.com/news/1082611_iconic-land-rover-turned-into-electric-car-research-vehicle

Daan

[faruksozen]

Hi,

I m a technical teacher.

I have a LR Defender model 1995.

I attached photos my Def.

I want to make ev conversion my Def.

I want to my electric motor connect directly to the transfer case (INPUT) as seen in the photo.

What do you think about this?

Best Regars.

Thanks.

[finnarne]

How big is the motor (Kw), how many rpm ?

Looks like you plan to use a drivebelt ?

What gear ratio on the drivebelt ?

[FridgeFreezer]

That picture appears to show a motor driving the rear diff, which means the motor has to move with the axle, which seems less than ideal. Also, that's a surprisingly skinny drive belt for the task.

Driving into the input of the transfer case (or into the PTO hole from the rear might make mounting easier) would seem a nicer idea.

As for motor size, top of my head: Ballpark OK engine for a Defender is ~100hp, which would be ~130kW, although I suspect the characteristics of electric motors means you don't need that much. I just googled the Tesla Model S and that has 270-310kW motors so maybe you do

Then you need to answer Finnarne's questions about rpm & gearing and do some maths to match the overall gearing to the vehicle.