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Re: "D/B" on shifter?

Posted: Thu May 20, 2010 10:33 am
by Dav
Daniel, production EVs (Tesla, RAV4-EV, EV1, S10) allow for timed charging. Their BMS tracks how much electricity into the battery and how much out. Any timed charger can be cut off before the end of the charging cycle and the car still knows how much juice it has. This is necessary to allow for "opportunity" charging while shopping or out for an evening. You charge for an hour and leave. No big deal.

This is also how you allow for "time-of-use" metering at home. Set the time for 1:00 AM and charge with cheaper electrons.

With the RAV4-EV there is a Palm application to tell you when to stop charging based on the % you want the vehicle to be full. You tell it a start time and current SOC, it tells you the end time.

This is also the easy way for those "mountain top" dwellers to take advantage of free electrons when heading down in the morning.
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Also, the RAV4-EV has what it calls "Turtle Mode". There really is an icon of a turtle on the dash. When you get really low on charge, the turtle lights up. A few miles later the turtle starts an audible warning and your speed and acceleration are dramatically reduced.

Re: "D/B" on shifter?

Posted: Fri May 21, 2010 9:26 am
by daniel
Thanks, Dav.

I'd still like to know what the Leaf will have, and whether there's a backup to the friction brakes when the battery is full. Something like the freight-train system would be nice to have.

I'd also like to know in detail how the regenerative braking on the Leaf will work. Will it be Prius style, where the brake pedal invokes pure regen braking, and only uses the friction braking when regen would not be adequate? Or will it be Tesla style, where letting off the accelerator invokes some regen, but the brake pedal uses friction brakes?

As I've said above, I'd like the accelerator pedal to do only acceleration, and the brake pedal to use only regen unless regen would not be adequate, and only then use friction braking. This would make coasting easier, would minimize wasting energy in the friction brakes, and would maximize the recovery of energy through regen.

Re: "D/B" on shifter?

Posted: Fri May 21, 2010 9:43 am
by JasonT
daniel wrote:As I've said above, I'd like the accelerator pedal to do only acceleration, and the brake pedal to use only regen unless regen would not be adequate, and only then use friction braking. This would make coasting easier, would minimize wasting energy in the friction brakes, and would maximize the recovery of energy through regen.
I don't see what is wrong with some regen braking happening when you let off the accelerator. I do the same thing in my manual car right now - I let off the accelerator, but stay in gear until the RPM gets down to about 2,000. This lets me use the engine compression to slow down the car before I have to use my brakes. Obviously I'm not generating energy when I do this (stupid ICE engine!)

I agree that I would rather have my brake pedal use regen until friction is required.

Re: "D/B" on shifter?

Posted: Fri May 21, 2010 10:23 am
by garygid
I agree with daniel,

I prefer no regen unless I ask for it by pressing the brake pedal slightly.

In my 2010 Prius, it is annoying to have to constantly "feather" the "e-pedal" to coast.

Re: "D/B" on shifter?

Posted: Fri May 21, 2010 10:34 am
by mwalsh
JasonT wrote: I do the same thing in my manual car right now - I let off the accelerator, but stay in gear until the RPM gets down to about 2,000.
I prefer to get the car out of gear completely when I see there will be a need to slow, and allow it to coast to a stop in neutral and @ 800rpm. If it turns out that the traffic starts moving again before I've stopped, I simply select the gear appropriate to the amount of speed I've managed to maintain and continue.

Re: "D/B" on shifter?

Posted: Fri May 21, 2010 10:46 am
by garygid
My 1994 Dodge Grand Caravan (recently buried prematurely by the Clunker program) would automatically (and rapidly) drop to idle RPM whenever my foot came off the gas. Its default operation in "Drive" was a "coasting" type of "overdrive", NOT the "normal" engine drag.

Re: "D/B" on shifter?

Posted: Fri May 21, 2010 12:18 pm
by Dav
JasonT wrote:Obviously I'm not generating energy when I do this (stupid ICE engine!)
<tongue-in-cheek-mode>
Jason, I'm surprised at this. Last dealership I went to the salesman told me I didn't need an EV that has regen, because ICE engines now push gas back into the tank when you brake! :shock:
Are you saying yours doesn't do that?
</tongue-in-cheek>

Re: "D/B" on shifter?

Posted: Fri May 21, 2010 2:45 pm
by AndyH
How much regen do we think we'll have if we shift into neutral? ;)

Re: "D/B" on shifter?

Posted: Wed May 26, 2010 2:24 pm
by JasonT
Ok, I'm going to link nest here
jhm614 made a post here http://www.mynissanleaf.com/viewtopic.php?t=460 that showed a Black leaf in the wild. In that post, Jason included the link to where the pictures came from - http://www.easyecar.com/electric-vehicl ... rst-drive/

In that page, we might have gotten our answer about regen behavior when the foot is off the "go" pedal.
The regeneration I[s] only very little when you take the foot of the accelerator and it goes to maximum when you apply the brake.
Now, this was still in a prototype car so things could change (heck, they could change this in software in the middle of the production run if they wanted to) but it's the closest we have to 'real' information so far.

Re: "D/B" on shifter?

Posted: Wed May 26, 2010 5:37 pm
by Stewy13
Just thought I'd post my quick thoughts about this engine regen "problem".

Most cars now are programmable, recently I changed the settings on my friend's Sebring car and all I had to do was read the manual, follow some simple steps and if you did it correctly the car chimed. Sounds like another pretty simple fix, why not have it programmable like that?

However why not take advantage of the fact that we have a navigation system in the car and that'd be a simple interface for the "user" or driver to input settings on the car. I imagine you could make it as basic as; Active Regen On or Off? Or have "profiles" for drivers/driving modes.
Or my favorite; make use of that lovely GPS technology in the car and have the car's computer change settings based on either basic geological position or take it a step further and have it change almost constantly in the sense of; highway driving - no regen needed, hilly/urban area - regen on, and so forth.
I'd imagine Nissan going as far as geological area if they ever did do something like this, but it'd be nice if they allowed us drivers to input our settings on an app like Google Earth, you could literally have it set street by street. Sounds excessive, call me a dreamer, but I think with something as smart as an EV, it just fits.

Now besides all the above, if shifting into Neutral eliminated the regen brakes from applying, I think it'd be an acceptable compromise as I've been doing the same whenever I drive (ICE, but it's good practice for my EV right? ;) )

(Note: I'm just referring to regen braking when you have neither brake or accelerator depressed, not regen braking in general.)