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Old 12-16-2007, 01:53 PM   #510 (permalink)
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Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
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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).
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown

has launched a forum for the efficient new Mitsubishi Mirage - fuel efficiency info for Geo Metro owners - electric car conversion on a beer budget
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