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Discussion Starter #1 (Edited)
OK .. Electric Lotus Elan.
I've been a lurker for some time - and want to extend a HUGE thank you for ALL the inspiration found on here 🙏

If it helps anyone else I used Instagram to log the conversion / build of a 50 yr old Lotus Elan: www.instagram.com/lotus_elon/ (or without Instagram: MAS Design Products Ltd. - Design Engineering Inventing ) notes are in posts (or hover over pictures for 2nd link)..

Background: recovering petrol head who LOVES the handling/steering/balance/lightweight of Lotus cars - especially 60's Elans (as fun at legal speeds as well as on track).

Mission: to keep same weight and handling balance, similar or better performance as ICE but no noise/smells/hassles (achieved - now testing and tweaking ✌ )

FWIW although superlight, original Lotus Elan's dirty little secret is they are terribly inefficient - 23mpg! - which was annoying - it now runs for free, powered by the sun (via pv panels).

Costs: tatty elan (£23K) but with rebuilt twincam engine, new chassis and suspension. Sale of ICE parts £8.5K Cost of most EV and conversion parts £12K, total £26.5K PLUS about 500 hours, blood sweat and tears (as an engineer).

Basic Spec:
  • 650Kg (1430lbs which is ~20kg lighter than before conversion)
  • Hyper9
  • 5 x Telsa Model X P90D modules (3 in front 2 in rear) ~28kWh (same weight distribution so keeps lovely steering/ handling)
  • best/worst range 200/100 miles
  • 6.6Kw Charger
  • simpBMS
  • Kept Gearbox, but not clutch - pulls from zero in top gear, crazy in 1st/2nd
Controversial - Some hatred from Lotus purists (even 1st owner who is in 70's .. "you did WHAT with MY car ? " !!). But, to be fair, a LOT of likes from more enlightened lotus folk.

Once again THANKs to all you generous folk who have inspired, freely shared information, links, and experiences of what works ( and what doesn't !!) 👍


120093
 
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Discussion Starter #2 (Edited)
Thanks for approving this post 😘
 

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Discussion Starter #3
'Lotus Elon' Got the Collecting Cars Treatment - by the looks of the comments its a marmite car :cool: There again many folk just dont like EV's :ROFLMAO:

Lockdown Project - Lotus Elan EV


Just for balance here it was before the conversion - an improvement ??

Elons engine bay after 20+ years in back of Miles Wilkins Workshop.jpg
 

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An early Elise has gone from old enough to be cheaper than a new car to old enough to be collectible - they'll probably never be cheap.
Bugger, missed my opportunity I guess. I almost bought one once about 12 years ago, time flies!
 

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That's a lovely build. I am in a similar position, got some much loved petrol cars including a Lotus Esprit, but I want to build an EV, so I hunted round for a starting point and found this Excel for sale with the powertrain and many other bits already missing. I'd like to achieve similar goals to your Elon - good handling and matching the original performance at least within reasonable road speeds. I only need enough range for local use as I will keep my petrol cars for longer adventures.

Cost is an issue, but I'm hoping to make it a daily driver rather than a hobby toy, so that will help with the justification.

121397
 

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I thought an Elise might not be crazy money now?
I saw an Exige locally for $18,000 (CAD, ~13,000 USD). And I thought "Okay, sounds pricey, I'll look around for them and pick up one for cheap".

Then I asked on the Lotus forums, and I think the cheapest anyone had seen one was one that was imported to Canada as parts-only racing car, never to be legal for road use, for $25,000. Otherwise north of $35,000.

"Cheap" to me is, like, I dunno, under 10-15k. Anything approaching a downpayment on a house, for a toy, makes me feel wastefully luxurious.
 

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I saw an Exige locally for $18,000 (CAD, ~13,000 USD). And I thought "Okay, sounds pricey, I'll look around for them and pick up one for cheap".

Then I asked on the Lotus forums, and I think the cheapest anyone had seen one was one that was imported to Canada as parts-only racing car, never to be legal for road use, for $25,000. Otherwise north of $35,000.

"Cheap" to me is, like, I dunno, under 10-15k. Anything approaching a downpayment on a house, for a toy, makes me feel wastefully luxurious.
Yeah my idea of cheap is not far off of yours.
 

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OK .. Electric Lotus Elan.
I've been a lurker for some time - and want to extend a HUGE thank you for ALL the inspiration found on here 🙏

If it helps anyone else I used Instagram to log the conversion / build of a 50 yr old Lotus Elan: www.instagram.com/lotus_elon/ (or without Instagram: MAS Design Products Ltd. - Design Engineering Inventing ) notes are in posts (or hover over pictures for 2nd link)..

Background: recovering petrol head who LOVES the handling/steering/balance/lightweight of Lotus cars - especially 60's Elans (as fun at legal speeds as well as on track).

Mission: to keep same weight and handling balance, similar or better performance as ICE but no noise/smells/hassles (achieved - now testing and tweaking ✌ )

FWIW although superlight, original Lotus Elan's dirty little secret is they are terribly inefficient - 23mpg! - which was annoying - it now runs for free, powered by the sun (via pv panels).

Costs: tatty elan (£23K) but with rebuilt twincam engine, new chassis and suspension. Sale of ICE parts £8.5K Cost of most EV and conversion parts £12K, total £26.5K PLUS about 500 hours, blood sweat and tears (as an engineer).

Basic Spec:
  • 650Kg (1430lbs which is ~20kg lighter than before conversion)
  • Hyper9
  • 5 x Telsa Model X P90D modules (3 in front 2 in rear) ~28kWh (same weight distribution so keeps lovely steering/ handling)
  • best/worst range 200/100 miles
  • 6.6Kw Charger
  • simpBMS
  • Kept Gearbox, but not clutch - pulls from zero in top gear, crazy in 1st/2nd
Controversial - Some hatred from Lotus purists (even 1st owner who is in 70's .. "you did WHAT with MY car ? " !!). But, to be fair, a LOT of likes from more enlightened lotus folk.

Once again THANKs to all you generous folk who have inspired, freely shared information, links, and experiences of what works ( and what doesn't !!) 👍


View attachment 120093
How do you get 100 - 200 miles range out of 28 kwh??
 

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Great looking build! I must have missed it when you first posted, but I took a look at some the photos on that link you posted. You really did a good job on weight to get 28kwh of batteries into a car that only weighs 1400 lbs! I am looking for input from others who are running Tesla modules - specifically about charging voltages, LVC values and voltage sag. Would love to pick your brain if you have the time to answer some questions.
 

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How do you get 100 - 200 miles range out of 28 kwh??
That's 140 to 280 Wh/mile, or 87 to 175 Wh/km... that's 8.7 to 17.5 kWh/100 km (the units used by Natural Resources Canada in their 2020 Fuel Consumption Guide). The worst end is typical for the moderate-consumption current EVs in urban conditions; the best end is far better than even the best current EV in urban conditions.

My guess is a combination of
  • low mass (the Elan is small and basic by current standards, and was small and light even for its time),
  • reasonably low aero drag (for a convertible),
  • favourable test conditions (low and constant speed), and
  • creative accounting.
But that's only a guess. ;)
 

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Discussion Starter #15 (Edited)
How do you get 100 - 200 miles range out of 28 kwh??
Hypermiling in top gear, under 50mph with a 650Kg TINY, 4 foot wide, slippery shape -- but admittedly apart from not slowing for any bends/roundabouts not as much FUN :)
 

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Discussion Starter #16 (Edited)
Great looking build! I must have missed it when you first posted, but I took a look at some the photos on that link you posted. You really did a good job on weight to get 28kwh of batteries into a car that only weighs 1400 lbs! I am looking for input from others who are running Tesla modules - specifically about charging voltages, LVC values and voltage sag. Would love to pick your brain if you have the time to answer some questions.
I've just started a 'Hyper9' thread to discuss errr, hyper9's and also sag .. in Motors.. (just waiting for approval - please )
but here is what I found:
121871


Otherwise TIPs
On tesla Modules - DONT ditch the control boards, and get a simpBMS from Tom De Bree (EVnut on socials) . Building on on work by EVTV, and a teensy - simpBMS works with the existing tesla boards, bleed resistors etc. and gives everything needed (temp, balance, charge control current display etc.) .

Use the built in battery cooling circuits - tesla are WAY ahead on thermal control for both heating AND cooling by a water circuit going right thro the pack. I pump battery water via a light radiator in the summer and an immersion heater in winter (to heat me too !!) .
I hope this helps - More pix on build 'thread' > Login • Instagram mas-design.com/lotus-elon/
 
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In the steady-state high speed section of that chart the car is running about 170 amps at 110 volts for 18.7 kW; that's at 7500 RPM, but what is the road speed? If that's 50 mph, that's 374 Wh/mile, which is not good even for highway speed. At that rate, 28 kWh would be gone in 1.5 hours or 75 miles. I'm guessing that the car is driven at a very low average speed to get the 100 to 200 miles range out of 28 kWh.

But the chart does show the 17% voltage sag at 800 amps well.
 

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Use the built in battery cooling circuits - tesla are WAY ahead on thermal control for both heating AND cooling by a water circuit going right thro the pack.
I've alway liked this idea, although the LG Chem system in the Chevrolet Volt is a better implementation. GM found that this level of heat transfer is not necessary for a typical EV (rather than a plug-in hybrid with a relatively small battery compared to the motor power), and uses the less expensive cold-plate system for their BEVs.
 

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Discussion Starter #19
In the steady-state high speed section of that chart the car is running about 170 amps at 110 volts for 18.7 kW; that's at 7500 RPM, but what is the road speed? If that's 50 mph, that's 374 Wh/mile, which is not good even for highway speed. At that rate, 28 kWh would be gone in 1.5 hours or 75 miles. I'm guessing that the car is driven at a very low average speed to get the 100 to 200 miles range out of 28 kWh.

But the chart does show the 17% voltage sag at 800 amps well.
The chart had nothing to do with range testing .. it was just a snippet of log files I found that nicely illustrated voltage sag.

I'm waiting for a longer thread to be approved - on this and hyper9 generally in 'motors' section.
 

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The chart had nothing to do with range testing .. it was just a snippet of log files I found that nicely illustrated voltage sag.
Yes, I understand that, but by coincidence it includes a handy bit of steady-state data for a hint at the energy consumption situation.
 
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