How do you gauge RAV4 EV efficiency?

[Michael Bornstein]

There are several Hypermilers on the Forum, and Tony frequently states how he can drive umpteen +++ miles on a charge. For my normal daily commute I feel good if I get 3.0 miles/kWh. Unfortunately, I can only see this number when I turn the engine off. The Efficiency gauge and the Trip Efficiency gauge is very coarse, having numbers at 5 and 10 and tic marks at presumably 2.5 and 7.5. I find the gauge very hard to read and am usually suprised when I turn the engine off and see a more accurate value. Is there some way on the two screens to get an accurate value of the current and rolling average efficiency? I know that you can count miles driven and bars on the battery gauge and get some idea of remaining range. I usually estimate between 6 and 7 miles per bar which gives a total range of 96 -112 mi on a standard charge and 120 - 140 on an extended charge, but this is only a total trip average not a current average and only valid if you remember to reset you odometer before you start. How do you guys gauge what you are doing?

 

[Khaihon]

I have the small screen show either the ECO Coach or the real-time efficiency while my center nav screen show the map on one side, and energy monitor on the other. The tiny screen is pretty useless to try and measure anything. The energy monitor could stand to use a couple more ticks.

Thanks to SoCal rush traffic, I can hypermile in the carpool lane without pissing off too many people since traffic is about 25-35 mph. I'm able to get an average of 3.9-4.0 mi/kWh on my 32 miles total daily commute. I regularly get my GOM to show between 120 and 137 miles on a standard charge. I have not extended charged in over a year.

On weekends where there's no traffic, my average falls to 3.3-3.4 mi/kWh as my average speed increases and hypermiling is frowned upon by my passengers.

 

[miimura]

I think the most accurate way to measure efficiency is to reset a trip odometer when done charging, then use RavCharge to get the Battery % after you stop. The integer battery percentage reported by the car through RavCharge has the most energy resolution of any reading available. However, I usually don't care and just drive the car. If I care about a certain driving segment, I make a point to glance at right side of the instrument panel when I turn the car off.

 

[TonyWilliams]

There are several Hypermilers on the Forum, and Tony frequently states how he can drive umpteen +++ miles on a charge.

My driving isn't "hypermiling". It's driving down a road with the cruise control on at a set speed. Not an average speed.

Therefore, 65mph will generate 3.4 miles per kWh of economy, which multiplied by 41.8kWh when the battery is new and at room temperature is:

3.4 * 41.8 = 142 miles

Anybody can do it, no skill required.

 

[TonyWilliams]

I think the most accurate way to measure efficiency is to reset a trip odometer when done charging, then use RavCharge to get the Battery % after you stop. The integer battery percentage reported by the car through RavCharge has the most energy resolution of any reading available. However, I usually don't care and just drive the car. If I care about a certain driving segment, I make a point to glance at right side of the instrument panel when I turn the car off.

Just reset the efficiency data from the appropriate screen on the center screen before your drive once "fueled up". It couldn't be easier.

Also, reset the trip odometer.

I do both when I plug in.

 

[Michael Bornstein]

Tony:

I didn't mean any disrespect :roll: You luckily live in SD, and if you stick to I-5 and I-8, the roads are pretty flat (CA-163 and I-805 are a different matter). Here in Bakersfield, even the roads that appear flat are actually on slight grades as we are surrounded by mountains. I have noticed in my Volt that the valley portion of I-5 is a slight incline towards LA and I will only get about 28 mpg. I have come back from LA with my RAV4 and used almost no electricity as I essentially coasted downhill on th "flat" portion of I-5. I therefore never see the 3.4 mi/kWh on my trips.

Just for fun, I am planning a trip to Las Vegas in a few weeks and I think I can make it with three stops, California City, Barstow, Baker, and then on to Vegas. My current concern is whether I can make it all the way up to Tehachapi as it is a steep hill, but once at the top I should be able to coast the rest of the way down to California City.

Does anyone have recomendations of good places to charge along CA-58 and I-15? I am a member of practically every network, and can charge from practically any outlet out there. Thanks for the advice.

Mike

 

[DevinL]

Just for fun, I am planning a trip to Las Vegas in a few weeks and I think I can make it with three stops, California City, Barstow, Baker, and then on to Vegas. My current concern is whether I can make it all the way up to Tehachapi as it is a steep hill, but once at the top I should be able to coast the rest of the way down to California City.

I did this a few weeks back en route to Utah. Between LA and Las Vegas only charged in Victorville and Baker. Made it from Baker to LV with a lot of juice to spare. Baker is a weird spot, but that RV parking lot is pretty much all we've got. Make sure you're aware of who you pay as there are a lot of chefs in that kitchen and they all start turning up a few minutes after you pull in.

On our way back we made it from Valley of Fire (~50mi NE of Las Vegas) all the way to Baker on one extended charge with AC on.

 

[TonyWilliams]

Tony:

I didn't mean any disrespect :roll: You luckily live in SD, and if you stick to I-5 and I-8, the roads are pretty flat (CA-163 and I-805 are a different matter). Here in Bakersfield....
Mike

Have you driven I-8? It's a 4000 foot pass between San Diego and the desert... Just like the Grapevine. Yes, I've driven it it.

I've driven the Rav4 EV over the pass between California and Oregon on I-5... also 4000 feet near Mt. Shasta.

Elevation is relatively easy to figure out:

One kilowatt hour = 2,655,224 pound feet of energy.

Driving your 4000 pound Electric Vehicle up a 1000 foot elevation requires 4000 * 1000 = 4,000,000 foot pounds of energy divided by 2,655,224 equals 1.5kWh of energy to lift the car.

1.5kWh of energy at an economy of 4 miles per kWh (250 watts per mile) = 6 miles of range used to drive up 1000 feet for a Nissan LEAF type car.

For a 5000 pound Tesla Model S (just two occupants) equals 5 million foot pounds to go up 1000 feet.

5 million divided by 2,655,224 equals 1.883kWh of energy to lift the car.

1.833kWh of energy at an economy of 3 miles per kWh (333 watts per mile) = 5.5 miles of range used to raise the car 1000 feet.

 

[TonyWilliams]

There are several Hypermilers on the Forum, and Tony frequently states how he can drive umpteen +++ miles on a charge.

So, using the above formula of about 1.7kWh of energy per 1000 feet to lift a loaded Rav4 EV for a 5000 foot pass is as follows:

5 * 1.7kWh = 8.5kWh consumed just for the elevation gain of 5000 feet.

Then, 65mph which would consume 3.4 miles per kWh of economy on level ground is now multiplied by 41.8kWh minus the 8.5kWh:

3.4 * (41.8 - 8.5) = 113 miles

Of course, it goes without saying (I hope) that your actual economy will be:

113 miles / 41.8kWh = 2.7 miles per kWh to climb the 5000 hill at 65mph.

 

[Dsinned]

Other than RAVCHARGER, there is another prospective "crowd funded" cell phone app (to be launched in October 2014) called "myEV" by MyCarma that promises to be of additional help. Several of us on this forum have contributed and are waiting for it to try out on our RAV4 EVs.

Here's the link for more info:

https://www.indiegogo.com/projects/myev-by-mycarma-electric-vehicle-logger-app

 

[jimbo69ny]

Other than RAVCHARGER, there is another prospective "crowd funded" cell phone app (to be launched in October 2014) called "myEV" by MyCarma that promises to be of additional help. Several of us on this forum have contributed and are waiting for it to try out on our RAV4 EVs.

Here's the link for more info:

https://www.indiegogo.com/projects/myev-by-mycarma-electric-vehicle-logger-app

Wow that app looks awesome! I just read their site, crowd funding site and watched their video. I want one! I reserved my place in line by giving them my email but I couldn't buy one as part of the first batch due out in October because the crowd funding campaign was closed. What a great app!

 

[4EVEREV]

Sounds like it is funding other projects. There is no decent business case to make an app for a car with 2600 units, the cost per unit would be very high. The math is easy and only a fraction of owners will be buying the app. Of course it makes sense if you can find takers above the $100 mark.

 

[Michael Bornstein]

Tony: My experience with I-8 dates back to when I worked on Point Loma for what was then the Naval Ocean Systems Center by the bay (which later merged with NELC on top of the hill). I lived in Encinitas and only drove I-8 as far as SDSU to visit my father who lived over there.

Anyway, My first recharge is either at the Hyundai Proving Grounds in California City or at one of a multitude of places in Lancaster. Where is your JdeMO Tony, there is a CHAdeMO in Lancaster. Unfortunately, all of these chargers are probably 30A and maybe even 208V. There are no KOA campgrounds in the area, and Plugshare doesn't list any available 14-50 outlets.

Next stop will be the KOA campground in Yermo (Barstow). This is over 100 mi from Lancaster (less from Hyundai), and as I will be travelling with my wife who is even less adventuresome than I, we will probably spend the night at a motel in Yermo.

Next day its off to the Mobile Home Park in Baker and perhaps lunch at the Mad Greek, then off to Vegas.

Any advice as to an optimal speed? I remember a thread which discussed time driving vs time recharging, but don't remember what the optimal freeway speed was felt to be.

Also, on the climb from Bakersfield to Tehachapi, would it be better to go at 55 or should I stick to 65? Again, I don't want to get to the charging station earlier, only to spend more time trying to recharge. Last time I drove this route, I was in my Jaguar and the average speed was about 75

I am amazed at the number of chargers in Lancaster, and even more so in Vegas. There is even a High School in Lancaster with an L2 charger, and the CHAdeMO is at an Art Museum!! The convenience of these chargers to the main Freeway CA-14 us something I would like to see in LA. Even the Toyota dealer in Lancaster has his charger listed.

Has anyone any experience with the Hyundai Proving Grounds in California City?? I have written them a letter (no e-mail listed on their website) to get permission to charge, but since I am coming on a weekend, they may be closed. If I can charge there, it would save me a lengthy side trip to Lancaster to find a charger.

 

[DevinL]

Any advice as to an optimal speed? I remember a thread which discussed time driving vs time recharging, but don't remember what the optimal freeway speed was felt to be.

Also, on the climb from Bakersfield to Tehachapi, would it be better to go at 55 or should I stick to 65? Again, I don't want to get to the charging station earlier, only to spend more time trying to recharge. Last time I drove this route, I was in my Jaguar and the average speed was about 75

With any trip that requires a charging stop, the golden rule is: the slower you drive, the faster you'll get there. On our Utah trip I tried to stay about 10MPH under the speed limit which put us at 55-70MPH. AC was on the entire time, too. The best thing to do is just find a big heavy tractor trailer and "get stuck" behind it. You don't need to draft, but let them regulate your speed and enjoy the added bonus of not feeling the annoyed glare of other drivers.

 

[Michael Bornstein]

True, but what about the glare from my wife. She's used to going 95 in her Jaguar (she had the sports car, I had the sedan). Now she enjoys her Volt, but still drives fast.

 

[DevinL]

True, but what about the glare from my wife. She's used to going 95 in her Jaguar (she had the sports car, I had the sedan). Now she enjoys her Volt, but still drives fast.

A couple hours waiting to charge in Baker will cure any urge that results in more frequent charging!

 

[Michael Bornstein]

To better continue this topic, I have created a new thread:

http://www.myrav4ev.com/forum/viewtopic.php?f=2&t=1244

that shows just how much time you would have to spend at the Mad Greek in Baker while your car recharges. The chart is based on a 100 mi journey on level ground using the data from Tony's Range Chart: http://www.myrav4ev.com/forum/viewtopic.php?f=2&t=67
I hope this helps people plan their trips.