100 Mile Range+ Conversion?

Has anyone done an EV conversion that resulted in a vehicle that could cruise at highway speeds (70 mph) and reliably go 100 miles per charge?

I may have access to a first generation MR2 and have seen that this is a good candidate for conversion. My design criteria would be:

Consistent 100 mile range.
Able to carry up to two people (350 lbs of passengers).
Cruise >70% at highway speeds (70mph)
Top Speed 80-85 mph.
Conversion cost – well I don’t want to spend what a Tesla costs or I would buy one. However, it would be worth the extra cost of more exoitic batteries if a reliable car meeting this spec. could be created.

What are the thoughts of the people on this Forum – is this reasonably possible with current battery technology?

To get that kind of range reliably, I would suggest an AC drive system with Lithium batteries. Like this one: http://www.metricmind.com/ac_honda/main2.htm You will also benefit from regen braking. Moreover, this is the technology that OEM cars use. This will easily get you past the 100 mile mark, maybe even more!


Well it’s been a almost a year since I posted above. I only got one reply and I am hoping that bumping this post will get more comments.

The MR2 fell through but now I have a line on something better (I think). A Saab Sonett (There was a guy in MA who converted a Sonett 1993 and claimed 50-55miles/charge). The car only weighs about 1700lbs stock which is getting close to the lotus elise that the tesla is based on (within 300-400lbs).

I am looking for opinions on whether I can reach my design goals with Lithium batteries and modern electronics (goals have changed slightly):
65-75mph cruise-max speed and 100 mile range.

I would also consider this successful if I came out with a 50 mile car on Optima’s or other lead acid and could replace with Lithium or other in a few years as the technology gets better and cheaper.

Also, this car has a fiberglass body on a steel frame (perhaps the steel frame could be replaced with aluminum for significant weight savings (would have to investigate this).

What are your thoughts?

I’m interested in something like this myself. I’m having a hard time finding any centralized source of information where people have actually done things like this.

Anyway. I don’t mind spending 8k on a conversion and another 10 - 15k on lithium batteries. An average new car costs around 16k anyway.

My goals are similar to yours. I just want to be able to go 60 mph and get around 100 miles per charge. My commute is 50 miles round trip per day which gets expensive so I’d rather pay for the payment on the loan rather than the payment for a new car plus the cost of gas :).

The info I’m looking for (and others I’m sure) is:
What I have to buy to achieve these goals
What I need to put it together
How much I can expect to pay

To meet your design goals it is going to be an expensive build. For continuous duty at 70 plus MPH an AC motor is the best choice. On the plus side to that is, AC motors allow for regenerative breaking. But AC controllers and regenerative breaks add to the cost of the build. For the range you are looking for, advanced technology batteries are called for. But again they are much more costly than lead acid. Also consider getting extra cells. I know of at least one EV using Lithium cobalt packs experienced a 20% failure rate.

If you are willing to put together you own battery packs, Sometimes you can find a good deal on bulk cells here. http://www.73.com/a/0696.shtml

Another way you could consider going is to build a 60-70 mile range car and mount an onboard charging generator. You charge on the grid at night for pennies per kilowatt, and then drive to work. When you get to work and park your car you start the onboard generator to charge up for the ride home. The onboard generator might only be 5 or 10 HP and take 6-8 hours to fully charge your pack but it will only use the fuel of a 5-10 HP engine running at its most efficient RPM, and you are only using gas for ½ of your commute.

If the generator uses 1 gallon each day you are getting 100 miles per gallon plus the cost of the nightly charge.

Just be sure that the charge controller you use can be configured to shut off the standby generator.

Thanks for the feedback.

The car, a Saab Sonet weighs in at around 1700lbs. The Lotus that the Tesla is based on weighs in at 1300-1400lbs (I believe). My thinking is that the Sonet can be made to weigh less if the steel tube frame can be replaced by aluminum. Point is I am approaching what Tesla started with, a light car. Perhaps I can get the weight down to 1500lbs before conversion. The guy who did the only Sonet EV conversion that I am aware of used 14 batteries and claimed a 55 mile range (45mph though).

If I built a similar car minus a couple hundred pounds and using lighter lead batteries (lighter than 1993) I would imagine I could at least come close to his performance. If the cost of LiOn batteries comes down over the next several years, and it should, perhaps for the same weight, I could double the Amp hours available and achieve the full 100 mile range. I would be able to re-use all but the batteries and charger and perhaps a BEC. Not to mention that I would have a great platform for study and development.

Check out the car and see what you think. I’m just brainstorming here. Check out video 1-2 at this link:


If not, a plug in hybrid looks like the ticket. I really want all electric though.

How did the EV

Just a couple of thoughts on your idea and comments on posts herein:-

The Saab weighs you say 1700lbs and the Telsa 1300-1400. Are you comparing apples with apples here. The Sonnet has engine and tranny (wieght??). The Tesla has an electric motor and battery pack. Check on this again as it’s not really a fair comparison in what I see here.

Secondly the idea of using the genset. It sounds like you have a steady place of employment - can you charge at work - if not why not leave the genset at the destination - no sense in carting it on every trip.

Finally have you looked at the concept of just buying a really fuel efficient car (like a VW diesel)?

I found this CALCULATOR page gives me ideas when tweaking specs for range and speed .