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Old 10-22-2008, 11:23 AM   #736 (permalink)
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Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
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Why not increase the pack voltage?

(Several people have asked whether there's any plan to upgrade the pack voltage, since we're about to come into a pile of what may be decent used batteries.

Of course looking at Pauls & Ben's 72v conversions, I have some envy issues.

But I think the car will stay at 48v. Why?
  1. The car's performance is adequate for its intended use. In a year of driving it, I've never been honked at or sent anyone into a purple rage - but I'm careful to choose routes (and/or travel times) where I'm not going to hold up the traffic flow because of the car's slow acceleration or power (hills).
  2. A new controller would be required.
  3. A new/additional charger would be required.
  4. A new DC-DC converter would be required.
  5. I'd have to make more LED battery bargraph monitors.
  6. The car is already close to the limit of GVWR. 72 volts would put it at or over, and also require a pack layout that would shift the F/R balance further to the back, requiring stronger rear springs, possibly losing the rear seat, and potentially hurting front tire traction in slippery conditions.
e-Turbo, maybe...

That said, I am still intrigued with the idea of adding a better 12v accessory battery (perhaps AGM), and planning a controller bypass circuit that would also switch that battery in series with the pack - a direct 60v motor connection for occasional faster acceleration, when wanted. Turbo boost.

I've toyed with this idea for some time (It's buried somewhere in this thread), but never pursued it because the car is passable on 48v (get it!? ). If I were to do it, it would just be for fun - for the technical exercise.
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