# Introducing Myself and My Project - Lotus Elan +2



## Own Little World (Sep 5, 2016)

Dear Forum Members,

As a former lurker and now member I would like to introduce myself and say hi from the South of England.

My project donor car is (at least was once) a Lotus Elan +2, which I found without an engine and transmission and a rusted petrol tank. This immediately suggested EV conversion to me, especially given its light weight construction (fibreglass shell).

As it happens I decided to put a gearbox back in it, not least because I like shifting gears but also to try and keep the revs in the efficiency sweet zone. I have a Ford MT-75 to put in and I am about to get a Sierra/Granada diff to replace the original Lotus one (which I don't think would handle the torques involved), once I know what ratio to go for.

I have a long, long way to go but I have a couple of initial questions about motor/controller selection that I hope you can help me with.

First things first, what do I want out of this car?

1) A range of 100+ miles as I may have commutes of around 70 miles
2) A final mass that does not destroy the Lotus handling. Original mass was 889kg so final mass not to much over 1000kg.
3) Good motorway passing abilities, although I will restrict myself mainly to country roads. It's nice to have it in the bag.
4) Performance that won't shame the bonnet badge. So around 110-120 mph. 0-60 similar to or better than original (<8.9 sec)
5) AC system with regenerative braking.

The drag factor, I guess, is around 0.4 and I think I might be able to improve on that with a belly pan. The X-sectional area is around 1.54 m^2.

So, I have looked at EVWest etc. to suss out the motor and controller options and I see:

1) HPEVS AC-51 @144V (46 160AH cells)- I estimate this gives me around 110mph, 125miles range to 100% DoD and 0-60 in around 10.9. Does that sound correct to you guys? The acceleration seems a bit sluggish. I may have estimated this wrong.
2) HPEVS AC-75 @144V (46 160AH cells) - obviously while stocks of AC-75 remain. I reckon around 112mph. 122 mile range to 100% DoD and 0-60 in around 10.7 seconds. Again, the 0-60 time seems high. Is this correct?
3) HPEVS AC-75 + alternative controller? The AC-75 at 144V does not offer much performance gain for the financial and mass (handling) penalty. Is there a better off-the-shelf controller?
4) Siemens motor and Scott Drive controller. I have not done any calculations yet as I am unsure how to start. I have a power curve available for 300V by I fear this means too big a battery. I was thinking more like 200V (~58 cells) but I have no motor or controller data for this voltage. Does this sound like a good configuration? It is already getting very pricey.
5) Siemens + Rinehart PM150. Eye-wateringly expensive option. Is this better than the Scott Drive? Is there any reason why this would be preferred?

To be honest, Option 2 looks good to me, except for 0-60.

I would love to hear your thoughts and suggestions.

Alec


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## Moltenmetal (Mar 20, 2014)

Suggest you consider saving money on the pack by using crashed Leaf or Volt stuff, then going with a dual motor AC option- or go DC if performance is your main driver rather than long term ease of maintenance and reliability.

If money really is no object, there are the Remy PM AC motors with the Rhinehart controllers...with the complication of a cooling system, but performance looks amazing.

For the braver still there are OEM motor/transaxles that can be repurposed and are rated for something like 80 kW continuous- the peak performance potential of those is pretty mind-blowing.

Personally in my Spitfire I find the AC50's instant 120 ft lbs of torque to be plenty of performance. I haven't calculated 0-60 - that would depend on shifting for sure- nor have I tested top speed, but speed just gets your car impounded and license suspended around here unless you take it to a track. My range (32s 180 Ah) is more like 60 miles to a practical DOD, which was all the prismatic LFP batteries I could afford and then some. Leaf or Volt cells are much more affordable.


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## Own Little World (Sep 5, 2016)

Hi Moltenmetal,

Many thanks for getting back!

If I can get away without a full radiator cooling setup then that would be preferable as ideally I would like to dam up the radiator vent and put an ABS belly pan on for improved aerodynamics.

Is yours a 96V Curtis controller?

I had not considered Leaf/Volt battery packs because it is difficult to tell if the previous owner has abused the pack previously. Is this possible in one of those cars or is there good battery protection?

I think I will size the system for a chosen voltage and then buy the packs at the very last moment, just in case there is any late developments in battery technology (and also to extend the calendar life of the battery). However, if I did see a real 2nd hand bargain I would be very tempted.

The more I think about it the more I am tempted to go for an AC-51 setup. With just a couple of non-street-legal mph less than the AC-76 and a bit more range it seems sensible.

You say you have not tested the 0-60 in your Triumph - have you any guesses? What does it feel like? Under 10?

Thanks again for getting back to me.

Alec


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## Tomdb (Jan 28, 2013)

With a car like the Elan, I believe the biggest issue will be finding room for all the batteries you will need for the 100 miles range.

The siemens option is a solid one, should do what you want, controller is up to you depending on your skill level.

What kind of budget are you looking at and what is your location?


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## Own Little World (Sep 5, 2016)

Hi Tomdb

You are right, there is not all that much room but there is:

- The space where the tank used to be, upright behind the rear seats. As it is upright the centre of mass would be quite high, so I can't go mad there.
- In the engine bay above and forward of the motor. The nose section is a bit too far forward and I need somewhere for the controller, DC/DC converters etc.
- Maybe room for 1 cell thickness (flat) along the boot floor, which I can cover with a sheet of ABS plastic or similar.

I don't have unlimited resources but I will be part funding the project with the sale of my MGB Roadster, just as soon as it is fully repainted. I have no real feel for the market but I would hope for about £8000. I will also keep costs down by doing much of the work myself.

So, I don't think I will be going top of the range in terms of motor/controller, unless 2nd hand. The HPEVS/Curtis price range seems good to me.

You say there is a choice of controller with the Siemens. What would be recommendations, say, with a limit of 200V)?

I am not far from Hastings on the South coast.

Thanks again,

Alec


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## Tomdb (Jan 28, 2013)

In the uk?

I would pick up one of the Hyundai 90kw units. http://www.evpartssale.co.uk/ev_motors_and_controllers.html

If you have any experience with electronics you should consider this with the brains from a Johannes heubner controller. No telling on what the motor can do when you lean on it. http://www.diyelectriccar.com/forums/showthread.php/another-homebrew-ac-controller-45909.html

Also good Brusa chargers there.

Edit: found a good dimension drawing http://www.haverstad.net/lotus/elan/image/elan_measures.jpg


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## prensel (Feb 21, 2010)

Own Little World said:


> My project donor car is (at least was once) a Lotus Elan +2, which I found without an engine and transmission and a rusted petrol tank. This immediately suggested EV conversion to me, especially given its light weight construction (fibreglass shell).
> Alec


It sometimes still amazes me that these classics are abandoned or stripped of their internals for whatever purpose.

Lucky man you that you found it and it could be great EV conversion !
I wish this type of conversion was even possible here in The Netherlands but unfortunally its not (anymore).


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## Own Little World (Sep 5, 2016)

Hi Prensel,

I think this car had been used purely to harvest the original engine. This particular donor car was in a real state. I think it had generations of ducks living in it. It was full of feathers, droppings and snail shells.

I have bought a 2nd hand, unused chassis which I will swap the running gear onto while working on the shell. I intend to re-inforce parts of the shell with carbon/Kevlar to improve the safety.

I will rebuild the drive chain including gearbox, prop shaft, diff, half shafts, new brakes. 

I have a lot of bits, like the seats and most of the trim but it needs upholstering quite radically. The dash needs rebuilding but the clocks are all there. I have about 60% of the brightwork.

Much of the car will have been completely replaced - but it will still be a Lotus as far as I'm concerned!


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## Own Little World (Sep 5, 2016)

Thanks again Tomdb.

That Hyndai setup looks great! I will do some more reading.

A few years ago I would have jumped into building my own controller without hesitation. However, time for me is very scarce to the point I am unsure why I am actually starting the project. As such I think I will look for a ready built set up but I am very interested by the link, if not for learning the theory behind it.

Thanks again!

Alec


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## Tomdb (Jan 28, 2013)

If you dont have alot of time, I guess mounting the motor above/just infront of the differential at the rear with some frame mods is out of the question.



















Looks very plausible as an install location, since the gas tanks where there. Should be room for the motor plus inverter. Leaving plenty of room for batteries up front.


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## Own Little World (Sep 5, 2016)

That is a good idea. The Hyundai controller in the link you sent would probably fit nicely, upright behind the back seat with maybe room for the motor below.

I don't know if I am ready yet to lose the stick shift, even if it is just 3rd and 4th.

There would be plenty of room in the engine bay though, as you say.


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## prensel (Feb 21, 2010)

I'm not sure how heavy the original twin cam engine was, i believe around 100 kg ?
I happen to have an 96V AC engine complete with matching Zapi controller and 32pcs Calb 130Ah cells eating dust actually...
This motor is BIG, around 100kg but you could do without the original gearbox and directly connect the propshaft to the engine. It has torque enough but maybe the max engine rpm is something t look at (calculate)

Thats what i would do.. IF i had a Lotus Elan without an I.C.E.....


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## Own Little World (Sep 5, 2016)

Hi Prensel,

Thanks again for the suggestions.

At the moment I am feeling more than 50% sold on the nearly new gear that Tom pointed to, mainly on account of the fact it runs at a similar voltage to what I had in mind (I think). I am going to ring them to find out some more details.

The thing is though, that buying this gear without documentation and warranties etc. makes me feel a little in need of some hand-holding.

From what I understand, people have managed to make use of the power stages of the Enova controller but not the control section - correct? Is that because there is no ICD for the Canbus interfacing or something like that?

Has anyone managed to productise a control section for it yet?

I am afraid I have not managed to read all 131 pages of the dedicated thread yet so I probably won't find out till Christmas at the rate I am reading it.

The gear looks like a real steal but I don't want to be left high and dry.

Alec


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## Own Little World (Sep 5, 2016)

So as not to meander about too much I will start a new thread relating to my Enova Controller questions.


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## favguy (May 2, 2008)

Hi Alec and welcome, nice to see another UK guy here, we are quite a rare breed 

You might want to hold fire for the moment before going too far with your conversion though, we are about to be hit by what appears to be a bombshell in the UK regarding getting our conversions registered as EV's as of the 1st November.

Please refer to this link:

http://www.batteryvehiclesociety.org.uk/bvsorguk/forums/viewtopic.php?f=20&t=3974&p=28130#p28130

Obviously we need more clarification on the exact issues for individual converters, but it might be more awkward/costly going forward...


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## Own Little World (Sep 5, 2016)

ooooh

That sounds depressing. Clearly we need standards but 6 grand test fees is going to kill the industry.

Just like we killed the solar energy initiative.

Drat.


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## 4Foxtrot (Apr 1, 2019)

Own Little World said:


> Dear Forum Members,
> 
> As a former lurker and now member I would like to introduce myself and say hi from the South of England.
> 
> ...


Hi Alex 
Did you do the conversation ? 
I'm too on south coast .
I went with the Hyper9 and split the pack front and rear to keep same weight distribution.
It ended up at 650Kg (20+kg ) less than with engine !
Cheers
Mark
(Poole)


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