Toyota Rav4 EV Forum
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Range Chart
http://www.myrav4ev.com/forum/viewtopic.php?f=2&t=67
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Author:  TonyWilliams [ Thu Dec 06, 2012 6:26 pm ]
Post subject:  Re: Range Chart

I'm posting these two pictures for folks who want to correlate the predicted range with reality. The first picture was taken this morning, after pulling a 6x12 foot box trailer a short distance yesterday. The second picture is after a 12 volt battery disconnect, which reset the meters to their default of 3.5 miles per kWh multiplied by 41.8 kWh. In both cases, the "gas gauge" shows full:


Image


Image

Author:  Dsinned [ Fri Dec 07, 2012 12:47 am ]
Post subject:  Re: Range Chart

Tony, I think the reason the battery discconnect default is 3.5mi/kWh is so when these cars are first sold by the dealers, or used for test drives, after the first full charge while still at the dealership, an unsuspecting customer will see a much better than expected (or EPA rated) driving range. This would most likely result in that customer being extremely impressed with the RAV4 EV, although not realizing that its initial driving efficiency will drop, appreciably - closer to the EPA's rating - depending on how they drive it, by the next time it is fully charged again.

A "sustained" average efficiency of "3.5" is a very high number to maintain, that implies hypermiling will be practiced almost religiously. Of course, that goes right out the window the minute the driver discover the "sport" mode and seemingly becomes intoxinated by the thrill of driving a Tesla infused SUV electrified powertrain. After driving the car like that for a while, the next refresh charge will net a much lower, realistic range. However, its that "INITIAL DRIVE" in a RAV4 EV that Toyota is hoping to make their very best first impression on prospective customers.

Author:  Sport Mode [ Fri Dec 07, 2012 7:04 pm ]
Post subject:  Re: Range Chart

Tony:

Love the chart!

I know on the range meter has 16 bars.

On your chart you show 20 bars for extended charge. Does the range meter change to 20 bars after
doing an extended charge? If so, I had no idea. If not, how does one know that
you did an extended charge?

Author:  TonyWilliams [ Fri Dec 07, 2012 8:56 pm ]
Post subject:  Re: Range Chart

Sierra wrote:
Tony:

Love the chart!

I know on the range meter has 16 bars.

On your chart you show 20 bars for extended charge. Does the range meter change to 20 bars after
doing an extended charge? If so, I had no idea. If not, how does one know that
you did an extended charge?


You currently don't know if you have an extended charge. It's a little silly, to be honest. No, there is not four additional bars on the gas gauge, but it should have.

I'll eliminate that from the chart.

Thanks!!!


Image

Author:  Dsinned [ Fri Dec 07, 2012 11:49 pm ]
Post subject:  Re: Range Chart

Tony, the only thing we don't know for absolute certain, without speculating, is the "actual" full energy storage battery capacity. Although, we have been able to estimate it from the energy it takes to do a full "extended" charge, which as you know turns out to be close to 50kWh. This is reflected at the top of the left hand column in your range chart. Also, we don't know if what appears to be ~8kWh of "extra" (unusable) charge is stored at the top or only at the bottom, or some combination. I suspect the latter. Anyways, thanks for your work on the range chart estimator as it promises to be a very useful reference guide.

A few suggestions . . .

1. Shade the column that corresponds to Toyota's "official" estimated range of 92 miles at 80% charge, and 113 miles at 100% charge, just to give users a sense of how much better (or worse) ranges will or can be depending on "how they drive". This also is the column that correlates to the EPA range estimate on the window sticker.

2. Add in additional rows of range numbers, so there is a 1:1 relationship for each value on the far left hand column. As it is now, interpolation is necessary which should be eliminated.

3. Add a footnote to explain that the the top of the chart reflects the difference between a full extended charge (highest row) vs. a fully standard charge (next to highest row).

4. Add another footnote to explain that after a fully extended charge, the first segment to extinquish on the battery range gauge represents a battery depletion of ~9.8kWh (actually, 7.8kWh of hidden charge + 2.0kWh after 1st segment used up). This corresponds to ~20% of total battery energy depletion from an absolute maximum, 100% SOC (~50kWh), or effectively ~23.4% of USABLE battery capacity (41.8kWh). Obviously, this is a disportionately larger drop/seqment than reflected in all other lower 15 segments. This is because the battery continues to deplete fairly linearly at a rate of ~2kWh (or 6%) per segment to use up the rest of its usable energy. When the last segment extinquishes, there is less than ~2kWh of further (hidden) charge depletion (perhaps only 1 or 2%, or even as little as a couple 100Wh, depending on battery condition) of usable capacity allowed before Turtle mode activates.

This might be too much information, and perhaps too much "guesswork", but I think a better interpretation of the left hand columns on the chart.

Author:  Dsinned [ Sat Dec 08, 2012 12:56 am ]
Post subject:  Re: Range Chart

Btw, the way you will know if you last had an extended charge or just a standard charge, is after the charge, before your next drive, be sure to reset the trip odometer. Then, as your driving watch for when the first (top most) segment extinquishes on the battery range gauge. This should happen within 30 +/5 miles (corresponding to ~9.8kWh of battery depletion) after an extended charge, or within about 6 +/-1 miles (or ~2kWh of battery depletion) after a standard charge. These predictions are based on an average driving efficieny of 2.5 to 3.5 miles/kWh. It is important to realize these are merely estimates. However, they relate to my last post, which is based on mathematical predictions, which correlate fairly well to Tony's latest range chart as well.

Author:  TonyWilliams [ Sat Dec 08, 2012 5:28 am ]
Post subject:  Re: Range Chart

Dsinned wrote:
4. Add another footnote to explain that after a fully extended charge, the first segment to extinquish on the battery range gauge represents ~7.8kWh (actually, 5.8kWh of hidden charge + 2.0kWh after 1st segment used up).


Actually, it is 7.8 + 2.0 until the first fuel bar extinguishes from a 100% charge.

Quote:
When the last segment extinquishes, there is probably ~2kWh of further (hidden) charge depletion allowed before Turtle mode activates, i.e. (2kWh/seg * 16seg) + 2kWh (hidden charge) = 34kWh.


The chart currently reflects "0-CCL" as that "hidden bar". Also, when CCL comes on, both climate control is limited as is power to the traction motor.

This is 3% SOC (if the battery is 50kWh when new, then this would give 1.5kWh to dead. Obviously, the BMS will limit us to about 2%, which means that CCL is only about 0.5kWh.

Climate control won't return to full power until 6.5% SOC. This is similar on the LEAF, except a far higher SOC (I froze my butt off one night to learn this).

Author:  Dsinned [ Sat Dec 08, 2012 6:15 am ]
Post subject:  Re: Range Chart

TonyWilliams wrote:
Actually, it is 7.8 + 2.0 until the first fuel bar extinguishes from a 100% charge.


Thanks for the correction, which I have shown in blue itallics above.

Author:  TonyWilliams [ Sat Dec 15, 2012 7:26 am ]
Post subject:  Re: Range Chart

I drove about 350 miles this past weekend, including driving to the first Rav4 EV Gen II gathering of owners in Irvine.

I recorded the following data from Saturday:

I set the cruise control on 75 mph for the 70 mile first leg with 2.6 miles/kWh while gaining 900 feet in elevation. The first fuel bar segment dropped off at 26 miles traveled.

The next leg was 46 miles and driven at 55 mph. At 116.7 miles traveled, only two fuel bar segments (Very Low Battery) remained. With 22 miles to go, I elected to stop at Kohl's for a 45 minute free charge (6.24kW with 208v/30a) with a ChargePoint unit.

This should have provided:

0.75 hours (6.24 * 0.86 charger efficiency) = 4kWh * 3.4 miles/kWh (60mph) = 13.6 miles additional range up to 4kWh * 2.7 miles/kWh (75mph) = 10.8 miles additional mileage.

At the Irvine meeting, with 138.7 miles covered, there were zero fuel bar segments and (Very Low Battery). I charged for three and a half hours at 208v/30a, which should have provided:

3.5 (6.24* 0.86) = 18.8kWh * 3.4 = 63.8 miles to 50.8 miles @ 2.7

That wouldn't quite get me home at 55-60mph, so I stopped for another 30 minutes of charging (2.7kWh @ 2.7 = 7.3 miles or 9.2 miles at 3.4)

211.8 miles traveled total with zero battery fuel bar segments equals good planning. 4.75 hours total charging at 6.24kW. Average calculated economy: 212 miles / (41kWh + 25.5kWh) = 3.2 miles/kWh (economy includes heater use).

Sunday had the following:

GOM = 113/121 in ECO Hi @ 72F
60mph with cruise control engaged (59mph measured by GPS)

Virtually identical garage temperature and conditions as Saturday: 57F in the garage with outside ambient at 50F in fog. Temperature steadily dropped to a low of 38F during the first leg of the trip. Elevation started at 580 feet, and went down to 340 feet, ending at 1475 feet for the outbound leg. Reverse for return except 60F-70F temperatures. 126.5 miles total round trip.

Fuel - Segment - Cumulative
Bar - Miles - Miles/kWh

16 - 29.9 - 2.8
15 - 3.0 - 2.6
14 - 2.8 - 2.5
13 - 1.4 - 2.5
12 - 6.8 - 2.6
11 - 4.0 - 2.5
10 - 6.7 - 2.5
9 - 7.3 - 2.6 (then reset economy, return trip downhill)
8 - 7.4 - 3.1
7 - 5.5 - 3.0
6 - 8.5 - 4.1
5 - less than 1 mile, charge 2 hours at 6.24kW, reset economy

11 - 3.8 - 3.3
10 - 9.5 - 4.0
9 - 5.4 - 3.9
8 - 3.7 - 3.6
7 - 9.9 - 3.9
6 - 3.5 - 3.7
5 - 4.4 - 3.8

Author:  Dsinned [ Sat Dec 15, 2012 11:09 pm ]
Post subject:  Re: Range Chart

Tony, your drive(s) last weekend makes for a good real world evaluation of what a GoM segment is equivalent to on a typical round trip of a few hundred miles. I came up with "5.64 mi/seg" average for your trip. Thus, from my earlier post to this thread, I suggested that 6 +/1 miles per segment could be used as a rule of thumb, based on a driving efficiency of 2.5 to 3.5mi/kWh. Btw, I extrapolated this figure from your range chart, and based on your real world data, I wasn't very far off.

I added up all your segment miles from segment to segment (18 total) and calculated your average miles per segment, which came out to 5.64. Your trip sounds like mostly freeway driving, so I am not surprised you averaged a little on the "low side", but still within a +/-1 mile variation.

Of course the ubiqutous disclaimer "YMMV" on these type of range discussions certainly applies here as well. :mrgreen:

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