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Re: "D/B" on shifter?

Posted: Wed May 19, 2010 12:10 pm
by Bicster
LTLFTcomposite wrote: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?
Personally, I'm better off with the A/C on. :lol:

My 2nd car is a very old Accord worth about $2000. When the A/C broke I had no problem spending $800 to fix it... this, for a car that gets driven approx. 1,000 miles annually. "It's not the heat, it's the humidity."

I suspect the Leaf will cut off unnecessary loads (at empty? 5 miles to empty?) and allow the driver to limp along at reduced speeds before it shuts off completely to avoid traction battery damage. How do other EVs respond in such a situation? EV1, RAV4, anyone?

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 12:33 pm
by garygid
Operation in the "low" (red) end of the "fuel gauge" (located on the "instrument panel" right side) might actually put the LEAF in a reduced-power "economy" mode.

However, that could be a safety issue if one suddenly lost "full-acceleration capability" just as they were trying merge onto the freeway into a line of fast-moving trucks, as often happens here.

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 12:41 pm
by Bicster
garygid wrote:However, that could be a safety issue if one suddenly lost "full-acceleration capability" just as they were trying merge onto the freeway into a line of fast-moving trucks, as often happens here.
I thought about that, too, but then dismissed it. How is it any less safe than running out of gas, where you experience a sudden and total loss of power?

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 12:53 pm
by AndyH
daniel wrote: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%.
None of the cell chemistries in the lithium-ion family like to be over charged or over discharged. All cells in the lithium family give a longer life when only charged to 90% 'gross' state of charge.

The user will not be allowed to bypass the limits the engineers set. If Nissan allows the user to use the 80% capacity range between 90% and 10% of gross capacity, then we will not be able to drive beyond the 10% gross or charge/regen above 90% gross.

If we want to charge to 95% of 'net' or 'user' capacity to allow that drive down a hill, that's one thing. But we will not have to self-censor in order to prolong battery life - the management system won't let us play in the danger zone. Additionally, unlike lead acid, there is no benefit to charging the pack after every drive, or in only using the top 50% of capacity.

Think of the lithium pack with a battery management system just like a fuel tank. The design of the tank won't let us overfill it or use more than the usable supply of fuel.


Re: "D/B" on shifter?

Posted: Wed May 19, 2010 1:08 pm
by garygid
With the HUGE range of a typical gas car (its fuel capacity FAR over all but very occasional needs), and the hidden reserves, MOST of us rarely even need to consider running out of fuel.

Those who drive the LEAF 20 to 40 miles a day and charge every night will enjoy a similar lack of concern.

However, those of us in the 60 to 100 mile range will be likely to learn some new trip-planning skills.

Well, try driving your ICE with a max of 2 (or 3) gallons in it (60 to 80 mile range), including all of the below-emply reserve (that most of us never use at all).

Then, limit your refueling to only ONE gas station near your house.

No, no one-gallon can for emergencies!

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 1:33 pm
by Bicster
I routinely drive my Subaru within 10-20 miles of "empty" according to the trip computer and with the fuel gauge firmly pinned on E. (Twice in the last two weeks, in fact!) Once I had a range estimate of "---" and you can bet I had range anxiety... Yet I've never once run out of fuel.

When I gassed up with "no range", I was able to put in about 1.5 gallons less than the stated fuel system capacity... so I'm guessing there was another 20 miles of range left. (I average about 16 mpg.) The thing is, you never know. I've read anecdotes from people who drive the same make/model/year car who ran out of fuel while the trip computer said they had 30 miles of range. In my case I believe the range estimate is pretty accurate because my driving patterns don't change much, but going from highway to city (or congested) driving will definitely throw off the range estimate.

With an EV I would obviously take the range a lot more seriously, and hopefully it would have better accuracy. (At least there's no mechanical component to the range estimate, and the BMS is what decides you're "empty" in the first place, not actually running out of juice.)

Overall I'd expect (in my personal situation) to have less range anxiety with a Leaf. I won't be avoiding fill-ups because I'm rushed or the kids are screaming, and plugging in at home will only take seconds.

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 2:33 pm
by AndyH
I agree with you 100% Bicster. I've been driving diesel cars since 1999 and there are plenty of times I've been in the North East where diesel pumps were few and far between (One can get complacent when their norm is Texas and diesel pumps nearly everywhere.) But one gets used to their vehicle (if they care to) and learns to 'color within the lines'. Or not and they learn to walk - same as gas or diesel. :D

Re: "D/B" on shifter?

Posted: Wed May 19, 2010 2:45 pm
by mwalsh
LOL! I've only ran out once in recent memory....

My Focus sedan has a reserve of about 45 miles, and I knew this one time that I had pretty well used all of that, but also felt I had enough to reach the station nearest our house. Well for some reason I didn't stop there - either they were too busy, or were getting a fuel delivery, something like that, and decided to go to the one on the next block.

Anyway, about half way down the block my car starts to cut out. It would restart, but then stall again once I got it moving (probably the remaining gas sloshing away from the fuel pump). So I had to half-drive, half-coast, and ended up rolling into the gas station on fumes (quite literally).

Don't want to do that sort of thing again anytime soon!

Re: "D/B" on shifter?

Posted: Thu May 20, 2010 6:29 am
by daniel
Dav wrote:... So stop charging at 95% ...
We don't know if this will be an option. As far as I know, only the Tesla offers this option. With other EVs, unplugging while the charger is still running leaves you with an unknown amount of charge.
LTLFTcomposite wrote: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.
Think about it for a moment, and I'm sure you will agree with me that while this could be possible, the Leaf is not going to have a charging program sophisticated enough to assess the surrounding terrain and stop charging early. I'm not concerned with what a clever programmer might dream up. I'm concerned with what Nissan actually is going to put in the car, and I'll give you 1000-to-1 odds that this is something they will not.

I am not worried about the safety of the Leaf. I drive a Zap Xebra after all. I am concerned that if they neglect a critical safety feature they may find their car declared not street legal at the last moment. Consider the Aptera: They figured they didn't need windows that open, and then at the last minute they realized that if you are stopped by a cop you need to be able to open your window, and suddenly they're faced with years of delay to re-design the car. I want the Leaf to succeed, because it will be a great step up for me, and I'd like to hear Nissan say that they've thought of this and how they have addressed it.

Re: "D/B" on shifter?

Posted: Thu May 20, 2010 7:15 am
by garygid
An opening window solution was NOT what delayed the Aptera.

Apparently the CEO felt it was necessary to re-engineer (almost) "everything".