2012 RAV4 EV vs. 2012 Chevy VOLT

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Dsinned

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These cars are totally different yet similar. Totally different because one is an plug-in EREV and the other a purely plug-in EV. Still they are quite similar in that both have almost identical max. HP/TQ ratings in their respective "Sport" modes. But I am here to tell you unequivocally, the 200lbs lower curb weight of the RAV4 EV gives it a definitive performance advantage and quite handily, which may seem somewhat surprising for an "SUV".

I'd say the Volt has the edge as a "smoother", quiter car, but the RAV4 is certain close to that description. Which is more comfortable? Also very close, but I'd have to say the RAV4, only because it seats 5 adults and simply is a roomier vehicle respect to its far larger cargo capacity.

I'd give the RAV4's telematic electronics the advantage as well. It has a one inch larger diagonal center console screen and quite a bit more functionality. The Volt's "green ball" is quite unique but the RAV4 simply has MORE of that kind of feedback that is more representative of "high tech" instrumentation. There is vastly more feedback about driving efficiency expressed in miles per kWh, and the RAV's i/p is quite elegant if not simply an impressive design as in WORLD CLASS!

As far as Onstar (MyVOLT, Remotelink, etc) compared to Toyota's equivalent in the form of their mobile app called EnTunes? No contest; Toyota got it RIGHT right out of the box! (Maybe, GM will catch up once the new ECOHUB cell phone app gets released.) TOYOTA includes two years of free roadside assistance and the RAV4 "SOS" button is for emergencies. ALso, Bluetooth pairing of a cell phone to the RAV4 provides a more satisfying link, including voice commands, which I think is better, as is the center console touch screen. Both cars NAV systems seem about equal, but the Volt has the best audio feedback "navigator" feedback.

Both these EVs are phenomenal cars, but the recently introduced, 2012 late model year RAV4 EV - imho - is the overall winner, which it really should be owing to its $10k higher sticker price. However, Toyota qualifies for $1k more from the CA rebate, and a "white" (zero emissions) HOV sticker vs. a green color AT-PEV (Advance Technology-Partial Emission Vehicle) for the Volt. In reality, for short mileage commuters, neither needs to worry about gasoline EVER!

The RAV4's massive battery (41.8kWh of useable capacity) clearly has much more to offer as far as an electrified vehicle. It is the same "low end" Tesla battery used in the Model S and weighs in at well over 800 lbs. Toyota warrants it at 8 years and 100k miles probably because it allows it to be fully (100%) charged for maximum range. EPA rates it at 102 miles but in actuality that is an average of its "normal" recharge capacity (35kWh or ~80% of fully charged) and its absolute maximum total capacity (41.8kWh). I like Toyota/Tesla's approach to address the issue of "range anxiety". With a conservatively rated 113 miles maximum range from an extended charged battery that should not be too much of a concern unless the RAV 4EV is your ONLY vehicle. (Fortunately, I have my VOLT to fall back on for longer trips.)

How long to charge that bad ass Tesla battery? On the standard charge cord, 115V, 12A? Forget it! 44 or 52 hours depending on the charging mode, regular (80%) or extended (100%)!!!

Toyota has a partership with Leviton which offers an EVSE L2 charging solution at 9.6kWh. That cuts down the recharge time to a much more reasonable (overnight, delay start to early morning completion) 5 to 6 hours. Unfortunately, the SPX Voltec L2 chargers apparently are not compatible with the Toyota. Both support the J1772 charge port connector but are NOT compatible. That sucks the big one I can tell you!!!

I opted for another DIY installation based on Leviton's 240V, 32A "plug-in" charger, which can fully recharge the RAV4 in about 7.5 hours, so I still get the job done during off-peak (lowest electric utility rate plan) hours.

Bottom line, the Volt is a GREAT car for a relatively short term commuter and enables the owner to get by with virtually no gas. It is also a "trip car", which the RAV4 is not. However, the RAV4 is also a GREAT car for even longer commutes, plus ousttstanding straight line performance that an SUV has no right to have . . . SERIOUSLY!
 
Dsinned said:
The RAV4's massive battery (41.8kWh of useable capacity) clearly has much more to offer as far as an electrified vehicle. It is the same "low end" Tesla battery used in the Model S and weighs in at well over 800 lbs. Toyota warrants it at 8 years and 100k miles probably because it allows it to be fully (100%) charged for maximum range. EPA rates it at 102 miles but in actuality that is an average of its "normal" recharge capacity (35kWh or ~80% of fully charged) and its absolute maximum total capacity (41.8kWh).

Be careful with battery warranties for EV's. In gasoline cars like the Volt, they must warranty capacity because it's part of the emissions certification. That's why the Volt battery uses such a small percentage of its total capacity; it can degrade for years, and still maintain like new performance.

The opposite is true of pure EVs. They can degrade at will, and you will pick up the tab when you decide you've had enough. That applies quite famously to the Nissan LEAF and of course, Tesla and this Tesla equipped Toyota Rav4.

The battery is 41.8 kWh, but like the LEAF's 24kWh, you never have access to all that capacity. The LEAF uses an amazing 93% of that capacity (22.3kWh), however after the power is extracted, only about 21kWh is "useable" (about 0.5kWh / 2% is left in the bottom at depletion). Significant variations below 21kWh happen with cold (its battery is completely at the mercy of ambient temperatures plus the effects of degradation).

The Tesla / Rav4 has many of the same parameters. I estimate 37.6kWh (90% of 41.8kWh) stored in the battery for use with an "extended" charge. I drove a rental Rav4 for 130 miles, averaging about 3.5 miles/kWh.

130 / 3.5 = 37.1

A normal charge should be 30kWh useable (80% of 37.6).

3.3 economy * 30kWh = typical 100 mile range prediction with a normal charge.

Of course, in hot or cold ambient temps, there will be somewhat less available with the TMS working to heat or cool the battery while drawing energy from the battery. I have no idea how Tesla/Toyota factors this into the economy data.
 
At the end of the warranty, 70% capacity is guaranteed. Real world Tesla battery users (Roadster) find about 2-3%/annum so far, and the early years are the most worstest; it tapers off.

PS; As testimony that (active or other) cooling pays off, an Alaska Roadster owner reports 3+ yrs, >40K miles with about half a dozen miles range reduction. Almost undetectable.
 
Brian H said:
At the end of the warranty, 70% capacity is guaranteed. Real world Tesla battery users (Roadster) find about 2-3%/annum so far, and the early years are the most worstest; it tapers off.

PS; As testimony that (active or other) cooling pays off, an Alaska Roadster owner reports 3+ yrs, >40K miles with about half a dozen miles range reduction. Almost undetectable.

That capacity warranty doesn't exist for Tesla Model S/X, or Toyota Rav4 EV. Or, just about any other pure EV.
 
Toyota consistently specifies, in all that I've read about the RAV EV, its maximum USEABLE battery capacity after an extended charge is 41.8kWh. The operative word here is "useable". Conversely, I have NEVER read anything that states maximum battery capacity in terms of a design limit . Nor, have I read anthing about what is its actual SOC lower limit. Surely, Toyota (and Tesla) has such an operational limit for normal or so-called "extended" use of the RAV4 EV's battery pack.

I am more familiar with the Chevy VOLT's battery limitations. GM has both lower and upper SOC limits. These limits have not been officially disclosed either, but the popular belief is the lower limit is around 20% SOC. The upper limit is probably somewhere between 80 to 90%, leaving about 60 to 70% of "useable" capacity.

Another factor to keep in mind is a VOLT's battery warranty (in CA anyway) is a whooping 10 years or 150,000 miles, which ever occurs first. By comparison, the RAV4 EV's (Tesla designed) battery is 8 years or 100,000 miles regardless of whether the owner is using standard or extended charging modes; with no actual restriction on the latter, other than Toyota's recommendation to not use extended mode repeatedly, to reduce the rate of battery capacity degradation.

The question remains, what is the "actual" RAV4 EV's theoretical or absolute max. battery capacity as designed?

Of course, it is very tempting to recharge in extended mode, even when a normal charge is sufficient for most around town driving situations. Not to mention, normal charging would be slightly cheaper and quicker to complete. However, there is just something almost irresistable about seeing a three digit number, "100" or higher, on the range estimator after a fresh charge.

As a further hedge to prevent battery capacity degradation, I believe recharging at less than the 10kW maximum, as allowed by the onboard charger, is probably a good thing. A slower rate of charge is better for the life expectancy of any battery, and same for the RAV4 EV's battery, regardless of whether it is charged in normal or extended mode. I recharge mine at 240V, 32A (or 7.7kW) using a Leviton EVSE L2 "Evr-Green 320" series charging station. This charging rate lowers the temperature rise on the battery, to help keep in from heating up as much and exercising the battery's TMS to keep it within optimum tempature range.

Another factor, I think that plays a role in a battery's health and longevity, is how OFTEN it is recharged. I plan to recharge mine typically once a week, early Saturday mornings when PG&E offers the lowest "off-peak" rates year round. That is, unless I have to drive round trip, anywhere near my RAV4 EV's maximum range. For most of my usual driving needs around town, I will follow Toyota's recommendation to only do normal recharges. Extended charging will be the exception, not the rule.
 
Dsinned said:
I am more familiar with the Chevy VOLT's battery limitations. GM has both lower and upper SOC limits. These limits have not been officially disclosed either, but the popular belief is the lower limit is around 20% SOC. The upper limit is probably somewhere between 80 to 90%, leaving about 60 to 70% of "useable" capacity.

Toyota Prius does that, too. Rav4 is not a hybrid, however. The current crop of pure EVs are about 90% stored energy to advertised capacity. The LEAF is actually 93%.

LEAF laboratory measured battery capacities for 24 kWh advertised capacity:

Energy from the wall from dead to 100%: 25.414 kWh
Energy from the onboard charger to battery: 22.031 kWh (86.6% charger efficiency)
Energy from the battery during discharge (USEABLE): 21.381 kWh (at room temperature)

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/veh_sys_sim/vss030_lohsebusch_2012_o.pdf

http://www1.eere.energy.gov/vehiclesandfuels/pdfs/merit_review_2012/adv_power_electronics/ape006_burress_2012_p.pdf


New 70F/20C temperature fully charged LEAF battery in easy to digest round numbers.
Gid = 80 wattHour units of energy (300 * 80 = 24kWh), doesn't apply to Rav4.
12 Fuel bars segments of 12 total (rated = advertised capacity):

-------------------KWH-------Gid------SOC%
Rated capacity: --24 ------- 300 ---- 100
Max possible. : ---24 ------ 300 ----- 100
Stored energy: --22.0 ----- 281 ----- 95 (4.1v per cell, 393.5 volts)
Usable energy: --21.0 ----- 281 ----- 95 (4.1v per cell, 393.5 volts)
Depleted cutoff: --0.5 ------ 5 -------- 2 (zero fuel bars remaining, 300v)



70F/20C fully charged, 50% dedraded battery.
NOTE: SOC remains at 100% when fully charged, even though 50% depleted:

-------------------KWH-------Gid------SOC%
Rated capacity: --24 ------- 300 ---- (not possible)
Max possible. : -- 12 ------ 150 ----- 100%
Stored energy: --11.2 ----- 140 ----- 95 (4.1v per cell, 393.5 volts)
Usable energy: --10.5 ----- 140 ----- 95 (4.1v per cell, 393.5 volts)
Depleted cutoff: --0.5 ------ 5 -------- 2 (no fuel bars remaining, 300v)


As a further hedge to prevent battery capacity degradation, I believe recharging at less than the 10kW maximum, as allowed by the onboard charger, is probably a good thing. A slower rate of charge is better for the life expectancy of any battery, and same for the RAV4 EV's battery, regardless of whether it is charged in normal or extended mode. I recharge mine at 240V, 32A (or 7.7kW) using a Leviton EVSE L2 "Evr-Green 320" series charging station. This charging rate lowers the temperature rise on the battery, to help keep in from heating up as much and exercising the battery's TMS to keep it within optimum tempature range.


I doubt you could quantify the heating difference and life expectancy between 32 and 40 amps. If you really want the battery to last, keep it in a meat locker with the TMS turned off, and trickle charge between 49% and 51% SOC.


Another factor, I think that plays a role in a battery's health and longevity, is how OFTEN it is recharged. I plan to recharge mine typically once a week, early Saturday mornings when PG&E offers the lowest "off-peak" rates year round. That is, unless I have to drive round trip, anywhere near my RAV4 EV's maximum range. For most of my usual driving needs around town, I will follow Toyota's recommendation to only do normal recharges. Extended charging will be the exception, not the rule.

I don't think how often you charge will be a determining factor. Quite the opposite, actually. Allowing the battery to use a broader range of SOC so that you can charge on Saturday is an economic decision, not a battery health one.

GM and Toyota got it right by using only 60% of the battery, and leaving the upper and lower 20% unused. Those batteries are charged "all the time" while driving, yet last a LONG time. If you follow GM/Toyota's hybrid battery model, and never let the battery get over 70F, I'd say you are doing the best you can do.

The 32/40 amp charging thing isn't a factor in the long life equation, with a 1/4C charge rate or less.

Hope this helps with understanding the battery.
 
Tony, do you happen to know if Toyota (Tesla really) employs "shorting resistors" switchable across each cell to level charge equally each cell's terminal voltage during recharge? This is done to all the Li-ion battery cells in the Chevy VOLT, measuring IR drop to within a few millivolts across each cell. My understanding is that this method prevents overcharging and/or overheating individual cells that recharge "faster" than others. No wonder these electric cars can be so expensive! :mrgreen:
 
Dsinned said:
Tony, do you happen to know if Toyota (Tesla really) employs "shorting resistors" switchable across each cell to level charge equally each cell's terminal voltage during recharge? This is done to all the Li-ion battery cells in the Chevy VOLT, measuring IR drop to within a few millivolts across each cell. My understanding is that this method prevents overcharging and/or overheating individual cells that recharge "faster" than others. No wonder these electric cars can be so expensive! :mrgreen:

I'm sure they all use something very similar. LEAF does, too. The maximum variation between cell pairs (they don't monitor every cell) is 50 millivolt on the LEAF.

It won't have anything to do with heating. It is merely measuring voltages during Open Circiut Voltage (OCV), and in the case of the LEAF, shunting the power from the highest cell pairs and when that's complete, minutes to many hours later, it will do a final charge back to 100%.

I don't have any idea of the specific protocols for Tesla, but we will. Since they use thousands of cells, I can't imagine that they monitor all of them.
 
The main advantages of RAV4 EV are-RAV4 EV is a Zero Emission Vehicle (ZEV) and has an EPA-rated driving range of 103 miles (92-mile range in Normal charge mode; 113-mile range in Extended charge mode), which is more than enough range for most daily commutes. It has impressive dynamic performance, and accelerates from 0 to 60 mph in 7.0 seconds in Sport Mode. RAV4 EV has the practical size and cargo capacity of a small SUV, and a 10-kW onboard charger that will fully charge the battery in five to six hours (240V/40A).
 
sam said:
and a 10-kW onboard charger that will fully charge the battery in five to six hours (240V/40A).

I suspect that you're just quoting something, but 240v * 40a does not equal 10kW... 9.6kW. You need 250 volts to hit 10kW.

Also, this is the power draw from the wall, so expect that the actual available (useable) energy put in the battery to be in the 85% area.

Therefore, a 9.6kW charge is likely only giving you 9.6 * 0.85 = 8.160 kW.

If you're planning a trip, and you can drive 60mph at 3.3 miles/kWh will give you about 27 miles per hour of charging from you home 40 amp charger. (8.160 * 3.3 = 27 miles).

However, understand that if you are on the road using a commercial EVSE charging station, it likely is using 208 volts at 30 amps in the USA / Canada, therefore your actual charging would be:

208 * 30 = 6.240 kW * 3.3 = 20.5 miles per hour of charging based on 60mph down a level road at 3.3 miles/kWh.

So, there's two rule of thumbs to remember.

Home 40 amp charger equals 27 miles gained per hour charged @ 60 mph / 3.3 miles/kWh

Away 30 amp charger equals 20.5 miles gained per hour charged @ 60 mph / 3.3 miles/kWh
 
Tony, what is your asumption of "3.3mi/kWh" at 60mph based on? That seems a bit higher than the average RAV4 EV will actually get on the highway. According to the ECO Dashboard app, the highest amongt the top 10 subscribers is 3.6mi/kWh, which is VERY GOOD! But, without extreme hypermiling, I suspect a typical RAV4 EV will get around 3.0mi/kWH for all around driving. On the other end of the scale, some percentage will only get bare 2.0mi/kWh, especially if prone to drive a lot in the "sport" mode. The Eco Dashboard gathers data based on real world driving, so it can be used to more realistically predict things like maximum charging range, miles/kWh, etc. I like the way it averages all trips taken over a 24 hour (daily) period, so if you take multiple drives per day, it tends to negate the skew factor resulting from taking a single trip, driving one way down hill because most people who commute drive both ways round trip in the same day.
 
Dsinned said:
Tony, what is your asumption of "3.3mi/kWh" at 60mph based on? That seems a bit higher than the average RAV4 EV will actually get on the highway. According to the ECO Dashboard app, the highest amongt the top 10 subscribers is 3.6mi/kWh, which is VERY GOOD! But, without extreme hypermiling, I suspect a typical RAV4 EV will get around 3.0mi/kWH for all around driving.

You're confusing steady state speed and economy with average reports on EnTunes.

My estimate of 3.3 at 60mph is just that. I drove it down the highway and got that economy in those SPECIFIC parameters.

I have not yet completed a complete survey, but I will. If you would like to get an idea of what can be done, check out this link:

http://www.mynissanleaf.com/viewtopic.php?p=101293#p101293
 
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