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gbarry42
Posts: 888
Joined: Mon Jan 10, 2011 5:48 pm
Delivery Date: 06 May 2011
Location: Moonlight Beach

Re: Range

Mon Jun 13, 2011 10:50 pm

I see where the issue is. But now I need to know how much energy is dissipated in the brakes at 20 MPH vs 75 MPH; it's going to involve friction and speed. Remember, the conjecture was about how long it took, not how much energy was required.

Then, after we're done here, I might have to claim that maybe we didn't get into this until physics 102...
And there goes the first capacity bar! At 24,000 mi on 9/9/2013.
Second bar at 30,500 mi on 2/7/2015.

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DaveEV
Posts: 6245
Joined: Fri Apr 23, 2010 3:51 pm
Location: San Diego

Re: Range

Tue Jun 14, 2011 12:56 am

patrick0101 wrote:Yes much more deceleration is needed to go from 75MPH to 55MPH than 20MPH to 0.
Aren't we forgetting that the amount of kinetic energy an object contains is relative?

As gbarry reminded us (us Encinitas folk gotta stick together! ;)) the question was related to how long it'd take to decelerate 20 mph.

Since F = M*A and we are accelerating the car the same relative amount, the force (limited by amount of friction between the tires and road) it takes to do so (and thus the time) is the same.

By definition:
Acceleration = (Start speed - finish speed) / time

Which tells you that if you apply the same force (assuming your tires have the same grip/friction at 75 mph as 20 mph) the amount of time is the same. Of course - you will travel a lot farther during that time!

Your typical car will exert about 1g under braking from top speed down to a stop.

Not explained very well - but I hope the point is made.

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DaveEV
Posts: 6245
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Location: San Diego

Re: Range

Tue Jun 14, 2011 1:00 am

davewill wrote:
mogur wrote:Not to the average ICE driver that sees one going slowly on the freeway and thinks, "There goes another one of those damn electric cars that can't keep up with anything or go anywhere - I'll never buy one of those!" They have no idea where you are going or coming from, or what you are doing and thinking; just that you are simply slow... Perception is reality to the uninformed...
Well, I'm not going to waste energy just for PR.
What's worse for PR - driving with the slow traffic on the highway - or draining it and sitting on the side of the road while waiting for a tow truck?

Herm
Posts: 3765
Joined: Sun May 23, 2010 3:08 pm
Delivery Date: 29 Aug 2012
Location: Timbuktu, Mali

Re: Range

Tue Jun 14, 2011 3:55 am

drees wrote: What's worse for PR - driving with the slow traffic on the highway - or draining it and sitting on the side of the road while waiting for a tow truck?
There is no bad PR by driving 55 on the right hand lane.. its a normal driving speed and lots of people do it. It is bad form to do the same on the high speed lanes, forcing people to pass you on the right is unsafe. A speed differential of 20mph is nothing.

trojanm50
Posts: 41
Joined: Mon Apr 11, 2011 1:38 pm
Delivery Date: 10 Jun 2011
Location: SF Bay Area

Re: Range

Wed Jun 15, 2011 11:33 am

Couple of issues here with driving at 55 on the fast lane- the carpool lane is on the left and when you drive at 55 you get stared at, people ride right up your rear and in some extreme cases, overtake you and cut you off when they are getting back.


Anyway- i wanted to report inconsistencies with my range after a full charge. I have owned the car for less than a week and i notice the range after a full charge is different each time. My drive has been mostly consistent on the freeway.

Day1: Eco mode showed 96 miles.
Day2 ECO mode showed 90 miles
Day 3 eco mode showed 100 miles.

I am charging 100% in all the cases above. of course, in practice i see the results are more or less consistent. today i drove 39 miles in some moderate hilly terrain, on the freeway and the range shows 68 miles left. My average speed was 40mph on the freeway while i drove quite some distance at 55-60 range.

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davewill
Posts: 5083
Joined: Thu Mar 17, 2011 6:04 pm
Location: San Diego, CA, US

Re: Range

Wed Jun 15, 2011 11:48 am

trojanm50 wrote:Anyway- i wanted to report inconsistencies with my range after a full charge.
There's a reason we call it the guessometer. :D Anyway, those differences are probably due to inconsistencies in your efficiency on the drive home the night before.
2014 Rav4 EV, Blizzard Pearl White
2011 LEAF SL w/QC, Blue Ocean, returned at end of lease

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gbarry42
Posts: 888
Joined: Mon Jan 10, 2011 5:48 pm
Delivery Date: 06 May 2011
Location: Moonlight Beach

Re: Range

Wed Jun 15, 2011 11:50 am

1. Do not believe the range number. It is a guess.
2. It will be lower if the climate control is on.
3. Don't believe the number.
4. It changes, based on the recent miles/kilowatt-hour number
5. Oh, yes, and Don't believe the range number.

You'll stay more sane if you watch the "bars" (though they are crude, too), and the amount of juice it takes to charge back up. If you have Blink EVSE, it will tell you kWhr directly. If you have something else, use the time it takes to charge as an approximation.
And there goes the first capacity bar! At 24,000 mi on 9/9/2013.
Second bar at 30,500 mi on 2/7/2015.

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gbarry42
Posts: 888
Joined: Mon Jan 10, 2011 5:48 pm
Delivery Date: 06 May 2011
Location: Moonlight Beach

Re: Range

Wed Jun 15, 2011 11:53 am

drees wrote:Of course - you will travel a lot farther during that time!
Yes, but the vehicle you are approaching will travel a lot farther, too! (Farther than the one at 0 MPH)
And there goes the first capacity bar! At 24,000 mi on 9/9/2013.
Second bar at 30,500 mi on 2/7/2015.

TangoKilo
Posts: 278
Joined: Tue Feb 22, 2011 1:39 pm
Delivery Date: 09 May 2011
Leaf Number: 2212
Location: Moorpark

Re: Range

Wed Jun 15, 2011 12:35 pm

2400 miles and climbing... Personally, I pay attention to the bars. The estimated numerical range indication is for "entertainment purposes only"...

LEAFfan
Posts: 4828
Joined: Fri Apr 23, 2010 6:08 pm
Delivery Date: 08 Jun 2011
Leaf Number: 1855
Location: Phoenix Area

Re: Range

Wed Jun 15, 2011 1:59 pm

TangoKilo wrote:Personally, I pay attention to the bars. The estimated numerical range indication is for "entertainment purposes only"...
That may be, but I still LOVE seeing 108 miles after an 80% charge. :mrgreen:
2013 LEAF SV Del. 2/28/13
2013 LEAF World Record for Most Miles Driven On One Charge-188 miles/8.8 m/kW h
4.8 kW DC PV ($ .91/W fully installed)/ Dec., 2010

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