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 Post subject: Real time indication of Miles/kwh
PostPosted: Wed Jun 14, 2017 6:00 pm 
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Joined: Mon Apr 17, 2017 5:30 pm
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When I complete a trip in my Rav the information display on the right side of the instrument cluster shows me the trips average miles/kwh in decimal form. While Im driving I see I can cycle through the various displays and I can see the bar graph of my miles/kwh instantaneous and average. However that bar graph is difficult to see to get an accurate number. Is there is display either in the instrument cluster or the main display that shows me my average miles/kwh in decimal form as Im driving and not just at the end of a trip?


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 Post subject: Re: Real time indication of Miles/kwh
PostPosted: Wed Jun 14, 2017 9:09 pm 
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Joined: Wed Nov 14, 2012 9:50 pm
Posts: 3807
Location: San Diego
Yes, press "map mode" from the navigation screen, then select the appropriate energy chart. When that pops up, you can select from "average" (smart) or "best" (dumb).


Last edited by TonyWilliams on Fri Jun 16, 2017 6:29 am, edited 1 time in total.

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 Post subject: Re: Real time indication of Miles/kwh
PostPosted: Wed Jun 14, 2017 11:13 pm 
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Excellent, thanks Tony!


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 Post subject: Re: Real time indication of Miles/kwh
PostPosted: Sat Jun 17, 2017 9:55 pm 
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Joined: Sat Feb 09, 2013 5:34 am
Posts: 42
DoctorTubaUF wrote:
Excellent, thanks Tony!


I tried it and there was no option to change from "Best"

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Ford Focus EV 2013 - GONE
2008 Toyota Prius
2014 Toyota RAV4 EV - Pearl (lease takeover used to replace my old one) GONE - Toyota messed with my battery
2014 Toyota RAV4 EV - Shoreline Blue - Bought still in warranty with only 11,700 miles after 3 yrs


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 Post subject: Re: Real time indication of Miles/kwh
PostPosted: Sun Jun 18, 2017 12:09 am 
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Joined: Wed Nov 14, 2012 9:50 pm
Posts: 3807
Location: San Diego
How to use the 2012-2014 Toyota RAV4 EV Range Chart:

https://www.dropbox.com/s/n8bhjas2wk5ry ... t.pdf?dl=0

Download and print the Range Chart:

https://www.dropbox.com/s/3bcv212xxsfd2 ... 2.pdf?dl=0

On the car:

A. Reset Consumption meter:

1) Press mechanical "home" button below the center of the navigation screen.
2) Press "EV" softbutton
3) Then press "Energy Monitor"
4) Select "Past Record"
5) Press "Update"

B. Display Energy Consumption during Map display mode:

1) Press mechanical "home" button below the center of the navigation screen.
2) Select "MAP"
3) Select "Map Mode" in lower left corner of screen. If this is not available to select, press "On", then "Map Mode".
4) Select "Energy Monitor"
5) Press the "go-back symbol" in the upper right corner
6) Confirm that "Consumption" is at the top-right of the display. If it says "Past Record", change to "Consumption". At the bottom-right of the display, it will show the average consumption. This will read 0.0 miles/kWh if it was properly reset. If not, go back and repeat step A.

C. Then, reset the trip odometer (black mechanical button between speedometer and energy gauge):

1) Press and release until desired trip meter is displayed
2) Press and HOLD button until miles go to zero

After you have completed these steps, you are ready to plan your trip.

First, let's stipulate that the "GOM" / estimated range on the dash is not to be used. This seems to be the hardest thing to overcome for many people.

The controlling value for range are two values:

1) Average miles per kWh
2) Available stored kWh onboard

If you need to travel 120 miles, and the battery is fully charged, you'll start with about 37kWh with a typical somewhat degraded RAV4 EV battery, therefore:

120 plus a 15% buffer equals 138 miles range required.

138 / 37kWh = 3.7 miles per kWh required to complete the trip with a 15% reserve.

That's about 55-60mph, on cruise control, according to the chart, but it could be a higher or lower speed. There are MANY factors that affect range, and the ONLY thing that matters is the "Average Miles/kWh" from reset.

If you drive 40 miles or so into your trip, and you're no where near 3.7 miles per kWh for this planned trip, YOU NEED TO SLOW DOWN!!! (Or find an alternate charging spot).

I recommend starting this trip with the cruise control on 60mph. If after 40-60 miles (just prior to the halfway point) the Average Miles/kWh are holding mostly steady at 3.4 miles/kWh for this example, the you MUST slow to 55mph.

If the Average Miles/kWh do not start climbing above 3.4 when you have reduced the speed by 5mph for the next 20 miles, you probably need to make sure that the heater is off, or start planning to find an alternate charging location. Slowing to 50mph on public freeways / high speed highways is probably dangerous.

Again, the GOM does not matter. If your battery is cold, it will consume more power to warm it up. If you run the cabin heater, you will consume more power. There may be a headwind. You may have a tire with low pressure. You may have a dog strapped on the roof. This is why the speed NOT a controlling factor in range... Average Miles/kWh is.

How will you know how much energy that your battery will hold? Do the "Tony-Test" to determine your approximate degradation:


Last edited by TonyWilliams on Fri Jun 30, 2017 11:36 pm, edited 1 time in total.

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 Post subject: Re: Real time indication of Miles/kwh
PostPosted: Fri Jun 30, 2017 10:40 pm 
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Joined: Sat Feb 09, 2013 5:34 am
Posts: 42
Ok, here was a test I ran where I reset the energy use at the beginning of the day. I drove 76 miles which included starting high going 1800' to sea level, then after a bit of flat, back up to 1800', down to 500' flat driving, then back up to starting point at 1800'.

I got exactly 3 miles/KWHr on graph.

Original charge was regular, recharge same.

Juicenet reported 32.695 KWHrs for a distance of 77miles = > or 2.3551 Miles per KWHr.

So why the huge difference between 3.0 and 2.3551?

I did use AC a fair amount of the time but the energy use should have reflected that.

This is why I worry about relying on the efficiency meter.

Could it be there is energy lost during charging batteries? BTW I purposely slow charge at 25A rather than 40A since it is likely easier on them.

_________________
Ford Focus EV 2013 - GONE
2008 Toyota Prius
2014 Toyota RAV4 EV - Pearl (lease takeover used to replace my old one) GONE - Toyota messed with my battery
2014 Toyota RAV4 EV - Shoreline Blue - Bought still in warranty with only 11,700 miles after 3 yrs


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 Post subject: Re: Real time indication of Miles/kwh
PostPosted: Fri Jun 30, 2017 11:41 pm 
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Joined: Wed Nov 14, 2012 9:50 pm
Posts: 3807
Location: San Diego
laguna_b wrote:
Juicenet reported 32.695 KWHrs for a distance of 77miles = > or 2.3551 Miles per KWHr.

So why the huge difference between 3.0 and 2.3551


Slowing the charge rate reduces efficiency. I recommend charging at 40 amps AC.

I have no idea what meter the Juicenet folks are using, but I'll guess that it's not expensive or uber accurate. But, taken at face value, then:

3.0 / 2.3551 = 1.27

Is there a 27% loss of energy? Maybe. If it was uber hot while charging, the air conditioner would be running the whole time, and for a lot longer time, since you reduced the charge rate.

Normally, I would expect about 15% loss.


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 Post subject: Re: Real time indication of Miles/kwh
PostPosted: Sat Jul 01, 2017 5:03 pm 
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Ok, another test from yesterday.... 47 miles driven 19.841 KWHr used. Efficiency metered at 2.9
Assuming full efficiency charging that would yield 2.37 Miles /KWHr actual versus predictive 2.9

The Juicenet is actually VERY accurate as it is certified to be used as a secondary meter in the PGE EV-B charging tariff. (The one where you get off the tiered rates ONLY for your EV but get a "free" charger)

I charge at night in an open garage with ambient temps between 50 - 60 due to marine layer. So, one COULD argue that rather than AC to cool the battery, it might use a heater if it has one.

I am not sure why you think 40A is better than 25A but curious as to why since it is the inverse of the DCFC issue which is that it reduces battery life thus it implies slower increases it. Could you elaborate?

_________________
Ford Focus EV 2013 - GONE
2008 Toyota Prius
2014 Toyota RAV4 EV - Pearl (lease takeover used to replace my old one) GONE - Toyota messed with my battery
2014 Toyota RAV4 EV - Shoreline Blue - Bought still in warranty with only 11,700 miles after 3 yrs


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 Post subject: Re: Real time indication of Miles/kwh
PostPosted: Sat Jul 01, 2017 5:15 pm 
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Joined: Thu Dec 27, 2012 10:55 pm
Posts: 580
laguna_b wrote:

I am not sure why you think 40A is better than 25A . Could you elaborate?



This is for the built-in charger of a nissan leaf, so not 1:1 comparable with a tesla charger:
http://www.mynissanleaf.com/viewtopic.php?t=8583

This is a pdf link :
https://avt.inl.gov/pdf/fsev/SteadyStateLoadCharacterization2015Leaf.pdf

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silver 2014 vin: 3533 24k miles, 2 x GEM EV
past ev's: 3 yr leaf 30k, 3yr rav4ev 34k


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 Post subject: Re: Real time indication of Miles/kwh
PostPosted: Sat Jul 01, 2017 6:30 pm 
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Joined: Sat Feb 09, 2013 5:34 am
Posts: 42
fromport wrote:
laguna_b wrote:

I am not sure why you think 40A is better than 25A . Could you elaborate?



This is for the built-in charger of a nissan leaf, so not 1:1 comparable with a tesla charger:
http://www.mynissanleaf.com/viewtopic.php?t=8583

This is a pdf link :
https://avt.inl.gov/pdf/fsev/SteadyStateLoadCharacterization2015Leaf.pdf


Thanks for this info!

Wow, this is interesting....both clearly point to higher efficiency with higher charge rates. I suspect the reasons are that since the charger in the vehicle had to reduce charge rates when operating below max, it does so by using switching like a thyristor or similar device to switch on and off which would create lots of harmonics and some heat loss. It is hard though for me to imagine that they charge with anything close to smooth DC (perhaps Tony knows) since the low impedance of the battery would dictate massively huge caps. But I suppose they could use switchers to raise the effective frequency of the charging current so caps would not have to be nearly as large....all my theoretical speculation.

So, I think the efficiency issue is answered and thus my NEXT experiment will be to run a multi-mile test like before and see what impact 40A charging has on the total consumption. I suspect it will fill a big part of the gap between theoretical m/KWHrs and what I have been seeing based on charging. I have a trip tomorrow likely stretch out over 150 miles where I can put the efficiency meter to the test as well. (expect one top up stop)

_________________
Ford Focus EV 2013 - GONE
2008 Toyota Prius
2014 Toyota RAV4 EV - Pearl (lease takeover used to replace my old one) GONE - Toyota messed with my battery
2014 Toyota RAV4 EV - Shoreline Blue - Bought still in warranty with only 11,700 miles after 3 yrs


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