# another Fiat Spider conversion



## dougingraham (Jul 26, 2011)

ronc said:


> Hi, Another new kid here. I acquired a 79 Fiat spider for free and want to convert it to a lone range vehical (350 miles). It looks like there are a lot of places to tuck in batteries. I also have a 25 hp 1700 rpm 3 phase motor that I would like to use. I have a goodly number of tools (lathes, welders, etc. and a little knowledge on how to use them).
> 
> I would like to ask a few questions:
> 1. Do the controlers adjust frequency as well as voltage?
> ...


I will answer your questions first and then some comments.

1) They could vary frequency but normally don't. The pwm frequency is what I am meaning. The commutation frequency will of course change with the RPM.
2) You can if you want. I would keep it. You need a LOT more motor if you eliminate the transmission and although you can shift without a clutch it is not as fast to do so. If you eliminate the transmission you will need to be able to select the differential ratio as the one in the car probably isn't close to what would be needed. If the ratio is too high you will have great acceleration but a low top speed. If too low then you wont be able to get out of your own way.
3) Electric motors are rated differently than you might think. If a motor is rated at 25HP that probably means for one hour. You can probably do 250hp for a few seconds with that same motor with the proper controller. The problem is finding the correct controller.
4) I assume you mean hobby type Lipo batteries. There are some people who have used them. I would not recommend it because of the complexity of pack construction. There is a very tiny cost advantage with using them but I feel the complexity of pack construction and fragility of the cells makes this a less than good idea. They only emit fumes if they are abused and fail. They are sealed and do not even have any kind of vent. It is not good practice to have the high voltage appearing anywhere in the passenger compartment. So the batteries should not be in the passenger compartment.

Don't get discouraged by this but it is really unlikely that you will be able to fit enough batteries in that car to obtain a 350 mile range. Assuming you can get 200wh/mile (this is highly optimistic) you would need a pack rated at least 70kwh. A pack of this size would weigh about 1400lbs (636kg). Using 98 of the 200AH GBS cells would give a max voltage pack for a Soliton controller but only a 62.7kwh pack. This will weigh 1185lbs (539kg) and use a volume of 13.3 cubic feet. At the very least you will need to beef up the suspension a lot and you will have pretty much no cargo space and the car will not be any fun to drive.

I would recommend something like an AC-50/curtis combo with 36 180AH cells. The car will gain a little weight but not much and still be fun to drive. You should have an honest range of around 80 miles to 100%DOD or a little over 60 miles to 80%DOD. This is kind of the sweet spot for Lithium conversions. Trying to increase the range on a car not designed specifically as an EV you run into diminishing returns because as the weight increases so does consumption and you reach a point where adding more batteries does not help. And long before you reach that point the car no longer is safe to drive because it cant accelerate and it cant decelerate or go around corners. And long before you get to that point the car would cease to be any fun to drive.

So don't get too ambitious with your project and you will end up with a really fun car to drive around. Once you finish your first car you will want to do another. Once you get done with the first you will have some idea of just how difficult making a 350 mile range car would be.

Best wishes!


----------



## ronc (Nov 30, 2012)

Thanks Doug for your insights. I live in the country so it take 100 miles just to get to town and back. Any running around in town is extra. I see this is going to be a bit tricky. Hmmmm. It's also up and down montains just to make it disier. But, I havent given up. Can't, already got the car partly stripped down.
Onward and upward, Ron


----------



## Duncan (Dec 8, 2008)

Hi Ronc
Have a look at your normal usage,
It's 60Km to the nearest "big" town for me
But I only go there once a month - the rest of my motoring is less than 20Km/day
So I am building a fast lightweight 2 seater with 30Km range

If you needed to go further occasionally then think about a trailer with more batteries or even a gen-set


----------



## tomofreno (Mar 3, 2009)

You said "another" spyder conversion so maybe you saw this one, if not some good info:
http://emotorwerks.com/cgi-bin/FiatConversion.pl

Yeah, as others said no way for 350 mile range, especially if you have to climb a couple thousand feet in elevation or more. Going up really eats up the energy. A 4% grade about doubles the energy usage of my car. Regen down the hill with your AC motor will give you back at best about 1/5 what it took to go up (least that is the best I do). Check evalbum.com to get an idea of range people get. As said, it's usually under 70 miles for LiFePO4, under 30 for lead acid at 60 mph. My little 2260 lb Suzuki Swift uses about 250Wh/mile at 60 mph, so you likely won't do better than that with a heavier pack to get more range.


----------



## ronc (Nov 30, 2012)

Hi Duncan, a trailer, hmm ... Woud not this bring more weight (batteries + trailer). 
Still, "all options are on the table" . Thanks for the input, Ron


----------



## ronc (Nov 30, 2012)

Yes, I saw stuff about Valery's indevers as a post on this forum. Thanks for the link to her website. I am going to search today for a variable frequency controller. Maybe if I go over 60 cycles I can get freeway speed without as much voltage or amperage.
(as he sallys forth into the frey ... Ron


----------



## Duncan (Dec 8, 2008)

Hi Ron 
_Maybe if I go over 60 cycles I can get freeway speed without as much voltage or amperage._

Afraid not - it takes power (volts x amps) to push a car along the road, the motor controller together is probably 80%+ efficient
You may be able to add on a couple of points but that will only reduce your power needs by 3 or 4%


----------



## zeroexcelcior (Aug 2, 2011)

If you're creative, you can actually fit quite a bit of lithium in a 124 spider without putting any batteries in the passenger compartment, but something to consider is how much weight you're adding to the chassis. A rough hand wave from my project is about 60 miles for 500 pounds of lifepo4. I really don't want to turn you away from your project but I think you'd need a trailer with more batteries or a genset to get that kind of range.

I strongly recommend keeping your transmission unless there's something terribly wrong with it.

All that aside, welcome to the electric Fiat club.


----------

