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Re: "D/B" on shifter?

Posted: Wed May 19, 2010 8:38 am
by daniel
EVDRIVER wrote:Yes, you can charge less than full and many people do this who reside at the top of large hills.
Does the Leaf specifically have this, or are you merely speaking of EVs in general? Clearly, your statement that "many people do this" does not apply to the Leaf, since the Leaf is not yet available. Of all the EVs I am aware of, only the Tesla Roadster has a partial-charge option. While I could unplug my Xebra before it is fully charged, I'd have no way of knowing how much of a charge it has. It could well have more or less than I wanted.

The partial-charge option on the Tesla is a great feature, but is more related to the characteristics of the particular type of lithium ion battery pack, which has a longer life when charged only to 90% than when charged to 100%.

Do you know for a fact that the Leaf will have this option?

And even if it did, it would not completely address the issue of downhill braking because an owner might not utilize it, preferring instead to maximize range.

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 9:03 am
by LTLFTcomposite
You know, this could be handled in software. Based on the GPS the car would know if it was being charged at a location at higher altitude, and proximity to routes with long downgrades. If those conditions are present the charger would cut out before the pack is fully charged.

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 10:56 am
by garygid
No, even knowing the topography of your charging location, the "computer" cannot know your intentions.

I believe that "charging" and "ranging" will become new skills for many, associated with operating a range-limited vehicle in a "sea" of sparce fueling points.

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 11:03 am
by Dav
Daniel, just get a RAV4-EV instead of a Leaf. With the wind resistance of a barn door, it never exceeds safe speed even on a steep downhill. :P

I don't think you are wrong, but I do think you are worrying about an inconsequential. It takes so much more battery to go up a hill than you recover coming down. Only, as you say, someone living at the summit of a very (very) high and steep hill would ever need to worry about it.

And in real life you cannot plan to be able to go to 100% of your range. So stop charging at 95% and you could never recover that 5% going downhill. Just not an issue. If you just HAVE to have that extra 5% - - well, maybe an electric is not the right vehicle for you, yet.

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 11:19 am
by garygid
Well, coming down from Big Bear is about 30 miles of mostly downhill, and that will require excellent mechanical brakes, but that is not really the biggest problem.

Getting the LEAF up there might be an adventure!

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 11:23 am
by Bicster
The only elevation changes my Leaf will ever encounter are freeway on/off ramps. Ok, maybe an underpass here or there. Houston is pancake flat. :mrgreen:

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 11:31 am
by garygid
No real fun in that ("flat").
Maybe you can test the range upper limits?

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 11:40 am
by Bicster
garygid wrote:No real fun in that ("flat").
Maybe you can test the range upper limits?
I agree that there isn't much fun driving to be had around here.

I'm sure the automotive press (and random attention-seekers on YouTube) will have a field day with range testing, no need for me to do it! Besides, my daily round trip commute will be 20 miles when the Leaf gets delivered. I can't imagine going 4-5 days without plugging in.

I am curious to know how far the car will limp on "empty" before it finally shuts down.

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 11:53 am
by LTLFTcomposite
garygid wrote:No, even knowing the topography of your charging location, the "computer" cannot know your intentions.
It might not know your intentions but it bounds what it possible. If you are charging the car in Houston or in a valley in a mountainous region there cannot be an issue with charging to 100%. If you are charging on top of hill there *could* be an issue, so you would end charging at less than full to be sure. It would be suboptimal if you were using the Leaf to run a local delivery service in a town that was entirely located on a mountaintop, but at least it would assure there is capacity to hold the braking energy if you decided to start heading downhill.

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 11:58 am
by LTLFTcomposite
Bicster wrote: I am curious to know how far the car will limp on "empty" before it finally shuts down.
You can easily see the car putting up a warning if the battery level is low recommending you reduce speed, particularly if the GPS sees you are too far from home. Also to turn off the A/C, although here we go again with that age old question are you better off with A/C and windows rolled up vs windows down?