Electric car conversion: Project ForkenSwift

[MetroMPG]

Hi Thalass...

Yup, that was for the total distance. It works out to 3 cents / km for me at the more expensive renewable energy rate. 2 cents at the normal grid rate.

Don't forget to factor battery replacement as an operating cost though. A lot of people omit that from their operating calcs, but the things are consumables, after all. Though a well designed car (ie. not the ForkenSwift) will prolong battery life.

Your 25k km/yr comment got me wondering... I wonder what's the theoretical maximum distance the ForkenSwift can go in a year with its current battery condition, range, and slow, slow, 10A 24v charger....

• 25 km - distance per charge (in ideal, warm weather conditions)
• 0.75 hours - let's say that's how long it takes to go that far
• 24 hours to fully recharge
• 24.75 hours - a full "drive/recharge cycle"
• 8760 hours in a year (non-leap)
• 354 "drive cycles" per year
• 8848 km - maximum theoretical distance in a year

I don't mean to discourage you though. It can be done, and you'll have a lot of fun doing it.

[MetroMPG]

PS - out of curiosity, what's the price per litre for petrol these days?

[Silveredwings]

"well over £1 per litre" : http://news.bbc.co.uk/2/hi/uk_news/7145006.stm

[Thalass]

We're pushing $1.40/L here at the moment, though by xmas that will probably be higher than $1.50, or even $1.60.


From my (very) rough estimates, my conversion will cost somewhere around 15k. It should take six years to recoup that cost on fuel savings alone, not taking loan interest into account. By that time the lithium batteries I'm planning on using will be getting on a bit. But by that time they ought to have come down in price, and should last longer, ect.


I figure that I should, at least, be no worse off (aside from range) than I am right now. And no worse off than someone who buys a new car every few years. Perpetual debt, but still cheaper than the current system. :P

[MetroMPG]

Well, I'm pleased to see you throwing around rough figures like $15k. That at least tells me you've done a bit of digging.

I've had more than a couple of messages from people asking if I'd make them a ForkenSwift that'll go 100 miles for "a few thousand".

[Thalass]

hahaha I wish!

I figure that if I have at least 50km of range, I can go to 95% of the places I usually go. With 100km range I can go to 99% of them.

The tricky part is finding a logical pricing system from the manufacturers! One place looks good, but charges per kWh, sells 7kWh packs, with a minimum buy of 10kWh. I'm not sure how much capacity I'll even need!


Lots more digging to do yet.

[MetroMPG]

If I were building an EV for 50-100 km range in the next few years, I'd personally be thinking about Firefly batteries over lithium.

Also, this just came up in another thread, but you folks in Australia have access to a style of vehicle that's nicely suited to lead-acid conversions: the UTE. North America gave up on this style of cars 20-30 years ago, but they really would be good for carrying lead, and for aeromodding.

---

Confirmed my thought that going further between charges makes for higher overall efficiency: 15.8 km in the last 2 days on 3.5 kWh = 94 eMPG (US).

[Thalass]

Those batteries are interesting... They might even be available over here by the time I start! hehehe.

I'm aiming for LiFePo4 batteries at the moment, because they are less prone to thermal runaway and explosions than LiPoly, while still being lighter and higher capacity than lead/acid. Still crazy expensive, though they're supposed to last longer so that it evens out.



As for utes... Yeah, they're great. You can load them up in the back with as many batteries as you want. Trouble is that they're usually only two seaters, and personally I need something that'll let me take the wife and kids places, too. That way I figure I'd recoup the costs a bit quicker than if I just went to work and back. But structurally they're great - lighter than your "trucks", but still built solidly for heavy loads.


I'll have to keep an eye on these Firefly batteries!

[modul8]

Originally Posted by MetroMPG

Don't forget to factor battery replacement as an operating cost though. A lot of people omit that from their operating calcs, but the things are consumables, after all. Though a well designed car (ie. not the ForkenSwift) will prolong battery life.
.

I have been lurking and watching progress on FS for some time with considerable EV envy. I am starting to wonder if it might be possible to resurrect my 98 intrepid as a full sized EV. A fuel hog at around 25mpg with its 2.7L POS engine, I wonder if it might do better as an electric.
Before you judge my choice of vehicle, please know that previous to this car I owned a sprint, a swift and a firefly---all of these have been recycled by now. Family life has made owning a larger vehicle somewhat of a necessity.

anyhoo, you commented on what you feel to be a well-designed car(or not)
so i have 2 questions: if you strained your beer budget by 500 bucks somehow, what would be the best way to invest it in the FS? to improve its design?
2nd, if you had an intrepid with a dead engine in your driveway, would you think it possible/worthwhile to convert it (automatic trans) and where would you start? what is the basis for good EV design, in your opinion?

[MetroMPG]

Hi, modul8...

I don't know about that Intrepid. The biggest strikes against it are: (a) its heft, and (b) the automatic transmission. Both are efficiency killers, and the added weight means you need more of everything to compensate: more batteries, bigger motor, more powerful controller... It's a vicious circle.

what is the basis for good EV design, in your opinion?

I'm no expert. But I've read some things the real experts say, and on that question they usually answer: since EV's are (usually) about maximizing efficiency, the best donor car to choose is one that was very efficient in its ICE form. That means the smallest, lightest & most aerodynamic vehicle that can hold the amount of batteries (usually lead based) that will permit you to meet your range goals.

if you strained your beer budget by 500 bucks somehow, what would be the best way to invest it in the FS?

500 bucks! Woohoo - Christmas comes early!

The car's biggest drawback is that it can't really be driven in "normal" traffic because it won't accelerate at anything you could call a "normal" rate, even flat-out.

The controller is part of the problem, limited to 225A max. But it's also a problem of worn-out batteries: 5+ km off a fresh charge, their voltage sags to dangerous levels when demanding those occasional 200A loads. So the driver has to constantly self-limit the amp draw when accelerating (and going up grades) by watching the volts (or ignore it, and risk ruining batteries).

Since $500 isn't going to get 8 new batteries here's what I'd do:

• upgrade from the used 48v controller to a used 48-72V controller

• add 2 more used batteries to the pack (I think that's about the limit before the car would need upgraded springs), for a total of 60v.

Pros: more power, less amperage draw for a given amount of work (= we can get more performance out of the old, tired batteries before they start to sag under heavy loads to damaging levels), more range.

Cons: unfortunately, it would complicate charging, since we don't have a 60v charger (but we do have a 36v + a 24v - of differing amperages though). Also, the added 130+ lbs would reduce overall efficiency a bit more.

So that $500 would have to pay for a used controller, plus a new DC-DC converter (the one we have.. and haven't yet installed... is 48v-12v).