[Eric318]

Hello all,

I recently bought a Fiat 500e to test EVs in real life for myself. And boy, I love it.

I also own a 1975 Jaguar XJ6C (the coupe version) with automatic gearbox that is in dire need of a new engine and gearbox. I do not drive it as much as I would want. Just getting it warmed up is a mini drama in itself. So I was thinking... poked about the Web a little and pulled out my calculator. Afterall, Jaguar themselves just produced a 1968 Jaguar E Type electric, so ...

I wonder if some of you experts could validate (or not) my numbers and the way I am approaching this.

To easily find my way through the seamingly infinite numbers of possibilities, I started from the vantage point of an existing EV with same weight as the Jag and characterisitcs close to what I would expect (with a twist, you willl see): the Rav4 E.

Rav4 E

• Curb weight: 3,440 lbs (the Jag is 3,600 lbs with all fluids and gas)
• Range: 95 miles (this is more than enough for me)
• Motor: 67 HP (hmm, may be we want a bit more oomph)
• Battery pack: 27.4 kWh (may want more juice for those burn outs...)

Out of the Jag will come:

• Engine: 606 lbs
• Tanks (and of course the weight of full tanks): 200 lbs
• Ancillaries: 60 lbs

So I would be left with a rolling shell weighing 2,734 lbs

After research, I narrowed down on a first EV blue print as follows:

• 88 HP AC motor with controller, 115 lbs, $4,700 here
• 30 kWh battery pack, with 52 of these for a total of 643 lbs, $12,656
• A whole bunch of ancillaries such as pumps for the autobox (will be replaced by a GM T700), the power brakes, power steering and AC, I estimate at 150 lbs and $3,000

This takes me to 3,649 lbs and around $21,000 + tax + one million hours of my time. The final weight is what I started with, I would expect around 80 miles range and a top speed of 75 mph!

Here are my questions:

• Does my calculus add up? What am I missing?
• Does this blueprint underpower the final result? Should I not aim for a bigger motor, more kWh and remortgaging the house?

Looking forward,
Thank you,
EF

 

[Duncan]

My tuppence worth!

First the best and cheapest batteries are from written off EV's

Second the best and cheapest motors are from written off EV's

So - how deep are your pockets?

In your shoes I would be buying a crashed Tesla and fitting the power unit and batteries into your Jag

Stick your location on the control panel - that may make a difference

 

[Eric318]

Hi Duncan, clearly your advice is worth a lot more than a few pennies

Indeed, the next step is to realize that, since I paid a whooping grand total for $8,700 for the quasi new Fiat 500e, and that there is a regular supply of these for the same price, I could in theory obtain a lot of hardware for less $ than the blueprint above.

Fiat 500e:
Range: 80 miles
Battery: 24 kWh 364 V
Motor: 111 hp

Twice that for $18,000...

A second hand Rav4 e, end of lease goes for $17,000

And there are tons of Tesla S in this neck of the woods, and the Tesla factory is about 7 miles away...

Is this really the best way to go? Dismantle an OEM car?

Thanks.

 

[kennybobby]

Your back-of-the-envelope calculations look reasonable with respect to cost and weight and pack size and range.

One other factor might be how fast do you want to accelerate from 0 to xx mph?

 

[Eric318]

Around $15,000 for a crashed Tesla S ?

Would the right parts have survived this sort of damage?

I am discovering a whole new world....

 

[Eric318]

Thanks Kennybobby, yes the all important burnout at the green light to annoy the chaps in their souped up F150... (the Fiat 500e is REALLY good at that, I swear, if it were a rear wheel drive, it would lift the front end...).

Is there a formula to capture "seconds to 60 mph"?

 

[Amitc7]

https://www.youtube.com/user/evwestdotcom

These guys do it professionally, they also offer advise for DIY guys.

 

[kennybobby]

..
Is there a formula to capture "seconds to 60 mph"?

Yes it's fun to blast away at the light--it never gets old.

back of the envelope calculations:
Horsepower needed to accelerate to XX mph in TT seconds
neglecting air resistance, tire friction, etc.

Mass equals Weight divided by “g” 32.2 ft/sec^2
speed in ft/sec equals XX mph times 88/60
Energy in lb-ft equals .5 times Mass times speed^2
HP equals Energy divided by TT divided by 550

example:
W = 3600 lbs, XX=60mph, TT=7 seconds

HP = 112 horsepower

 

[Eric318]

OK then, so one Fiat 500e motor should do the trick? Wow. Lets put 2 anyway

 

[brian_]

Have you ever seen a 112-horsepower car get from zero to sixty in 7 seconds? No? Neither have I.

The basic physics is sound, but omits a couple of details:

1. That's a continuous power level. Since the engine or motor cannot produce its peak power at all speeds, an actual engine or motor will have substantially higher peak power to get that acceleration.
2. That assumes that all of the power is going into accelerating the mass, but you also need to overcome drag, so add whatever power it takes to keep the vehicle moving at about 40 mph.

Yes, a pair of Fiat 500e motors would be a better match... or at least one motor from a production EV with more power.

 

[Duncan]

Around $15,000 for a crashed Tesla S ?

Would the right parts have survived this sort of damage?

I am discovering a whole new world....

Hi Eric - that one has already been stripped - and it was going for $200

Tesla's are expensive cars - but with the aluminium body shells they are very expensive to repair
It does not take much damage to write off a three year old Tesla

The bits that you want are probably the most protected on the car! - the battery is low and very strong - the motor/reduction box is also very low and at the back of the car

Most other vehicles are higher off the road and will take out the (expensive) bodywork - and leave the good bits
Also the Tesla is a very safe car - five stars - that actually tends to make it more expensive to repair

Have a look on YouTube - there are a number of people who have rebuilt crashed or even flooded (Not sure if I would risk that) Teslas

 

[itchyback]

I'm putting a wrecked Tesla Model S motor and Battery in my series 1 xj6. we should team up!
I have the motor (120kg) and batteries (400kg + boxes/ mounting bits) and have emptied the vehicle of ICE stuff
let me share the weight with you.
Exhaust 14.2kg
radiator 13.7kg
air intake 6.8kg
radiator bits 3.5kg
AC radiator 3.8kg
exhaust back boxes 12kg
Engine 289kg (including headers and auxilary bits)
gearbox 79kg
petrol tanks 17.8kg
drive shaft 11kg
diff ?? about 15kg (i havent taken it out yet)
total 460kg or 1014 pounds.

Depending what you put back in you could get close to the original weight. I'm putting in AC, power steering, Tesla brake booster and making it as original looking as possible.
Some things to consider will be upgrading the front brakes and changing the rears to outboard brakes as the inboard ones wont fit with the drive unit there. Im working on the battery boxes now.

 

[Eric318]

This is excellent information, thank you.