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RAV4 Prime power adequate for sustained uphill climbing

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#21 ·
crisps said:
177 hp ice engine plus electric to make roughly 219 max power
same deal that extra 42 HP comes from battery
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I believe that due to the maximum rotation speeds of mg1 and mg2, it would be hard or impossible to coincide the ICE's power peak RPM, wheel speed, and peak power from mg1/mg2 for all wheel speeds. So it remains to be seen how the performance and battery regeneration is at high power demands at different vehicle speeds.

The prime with the ten times larger battery is going to have a much greater reserve in case the instantaneous demands exceed the ability to put charge back into the battery.
 
#22 ·
RavForTwo said:
I believe that due to the maximum rotation speeds of mg1 and mg2, it would be hard or impossible to coincide the ICE's power peak RPM, wheel speed, and peak power from mg1/mg2 for all wheel speeds. So it remains to be seen how the performance and battery regeneration is at high power demands at different vehicle speeds.

The prime with the ten times larger battery is going to have a much greater reserve in case the instantaneous demands exceed the ability to put charge back into the battery.
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The quoted numbers for HP are from the Toyota specs. The sum of the HP of the ICE and MGs is higher. Toyota's specs take the factors you mention into account when giving total HP numbers.
 
#23 ·
cdherman said:
The clever engineers at Toyota are ahead of you. The "Hybrid Synergy" setup with M1 and M2 and the funky planetary variable gear ratio allows for some amazing tricks. The one that you folks embarking on a sustained climb will like is this: Its NOT just regenerative braking that can charge the battery. When the battery capacity gets so and so low, the car knows that could potentially need the battery for acceleration, so it starts to use M1 or M2 (that part escapes me right now) to generate electricity to charge the battery. No braking involved. This will result in the little 2.5l 4 banger running pretty much constantly, BUT it will have a reserve charge in the battery to handle periods of additional acceleration.

Now, could you overdo it? I suspect at some point, especially if you were to try to maintain say 85 mph going up a mountain, or you were towing at high speed up same mountain, well then at some point the 4 cyl engine has no reserve left to charge the battery. Then the battery could start to get less and less charge. HOWEVER, I suspect Toyota has made this impossible. Why? Because the traction battery MUST keep a certain amount of charge always, since it functions as the starter as well, the engineers would probably throttle your speed before they let you deplete the battery. This is an educated guess on my part, but I bet its true.
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Toyota's hybrid system does definitely do a great job of keeping some reserve in the battery. That said, my first of four Toyota hybrids was a Prius c. Just once I managed to deplete its traction battery. I was maintaining 80-85 miles an hour westbound on I-70 in Utah on a very very long sustained gradual upgrade. About a mile before the summit the car literally ran out of power. The speed dropped down to about 55 miles an hour with the gas motor running full blast. I crested the summit, and it promptly filled the battery back up.
 
#24 ·
We have a 2029 Rav4 Hybrid. We take it to Lake Tahoe, from the Bay Area, often. We've taken it on a 7 state tour from the Bay Area to: Tahoe, Vegas, Salt Lake, Denver, Rocky Mountain Park, Boise, Bend, Portland, and home......lot of mountains. Never a problem and loaded down with groceries, 2 people, large roof box, and extra gear. Never a problem with power, but the gas mileage takes a beating! Oh, and yes, that little 4 cyl motor makes some noise. 40k and counting.
'
 
#26 ·
TZX4 said:
Toyota's hybrid system does definitely do a great job of keeping some reserve in the battery. That said, my first of four Toyota hybrids was a Prius c. Just once I managed to deplete its traction battery. I was maintaining 80-85 miles an hour westbound on I-70 in Utah on a very very long sustained gradual upgrade. About a mile before the summit the car literally ran out of power. The speed dropped down to about 55 miles an hour with the gas motor running full blast. I crested the summit, and it promptly filled the battery back up.
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One of the design features that allayed my worries about the same thing happening with the Rav hybrid is that the ICE makes 176 HP, which should be enough to sustain 80-90 MPH up a 6-8% mountain freeway grade. It's really just repeated passing attempts while going uphill that concern me about running down the HV battery without the ability to replenish the charge.

I've played around with the charge level of the hybrid battery while just driving around town and it's uncommon to get the charge showing three bars or less. Even creeping along slowly in EV mode, the ICE will start up seemingly when it is at three bars so maybe that's the lower threshold when it's used driving in the mountains as well.

Does anyone know if the different modes (eco or sport) affect SOC management of the HV battery in a hybrid?
 
#27 ·
TZX4 said:
Toyota's hybrid system does definitely do a great job of keeping some reserve in the battery. That said, my first of four Toyota hybrids was a Prius c. Just once I managed to deplete its traction battery. I was maintaining 80-85 miles an hour westbound on I-70 in Utah on a very very long sustained gradual upgrade. About a mile before the summit the car literally ran out of power. The speed dropped down to about 55 miles an hour with the gas motor running full blast. I crested the summit, and it promptly filled the battery back up.
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I think your "test" pretty much confirms my theory. At some point, the computer just says "hey buddy, I cannot let you drive this fast anymore because the battery is about to be dead" And it fixes the problem by slowing you down, but NOT slowing the engine. Your engine was running full bore as you experienced, to generate power to replenish the battery.
 
#28 · (Edited)
cdherman said:
I think your "test" pretty much confirms my theory. At some point, the computer just says "hey buddy, I cannot let you drive this fast anymore because the battery is about to be dead" And it fixes the problem by slowing you down, but NOT slowing the engine. Your engine was running full bore as you experienced, to generate power to replenish the battery.
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let’s do some math..

I think the Prius C battery was in the 1KWh realm. It’s well known that Toyota conservatively protects the battery, protecting the top and bottom end. So let’s assume 0.8 KWh usable. It also probably wouldn’t charge the battery to full under a command for full power, so we are talking about a charging demand of 0.4 KWh to get the battery to 50% (I’m making a lot of #’s up for illustration purposes). MG1 ~15KW max. That’s 90 seconds to produce the required .4KWh energy. And I think conservative because the car wouldn’t generate that much, it would only put a 2-3 “bars” into the battery.

73 HP engine. That’s 54 KW. 15KW consumed by MG1 while charging. That’s 39KW left for the wheel or 53 HP. That’s what my grandmothers Isuzu I-Mark was rated at. This is based on specs at sea level.

A long climb was mentioned. I70 crests at 7K feet. Non turbo engines lose about 3% power for every 1K ft elevation change. That’s 21% less power at the top than at MSL (which is where HP ratings are derived from). So back that out of my #’s above and you’re driving a 37 HP car while it briefly recovers (42.6KW - 15KW charge load = 27.6KW = 37HP). IMO it’s altitude as much or more than the drivetrain.

Forget the hybrid system altogether. A 73HP car would SUCK climbing at 7k feet. What I think was happening was the HV system was supplementing power for the climb until it ran out. It wouldn’t be as much the generation losses, it was that the extra power from HV was gone.

Now with the R4H/P platform we have an engine that produces ~2.5x the power. R4 is not 2.5x the weight. It’s never going to be a problem unless you’re towing something very heavy.
 
#29 ·
I completely understand your question. I drive a Ford Fusion Hybrid company car. Acceleration uphill is horrendous.
pressing the accelerator anywhere between 25-100% doesnt matter. It doesnt move any faster and feels like the motor is connected by rubber bands. The Rav4 Prime is like a sports car in comparison.
The acceleration will bring a huge grin on your face.
 
#30 ·
Toyota is one company that has long tested its vehicles at places like Pike's Peak and done so on very hot days. Overheating has never been a problem with their cars and trucks. Quite different with American cars and trucks where often only have the radiator core space was used and one needed to get a special tow package to have both cores installed at the factory. The addition of factory radiator fans has also helped when going up long grades where the heat output is the highest and there is less air moving through the radiator fans.

These small cars are more affected though by rooftop cargo carriers and any tow load with a trailer. But the fuel economy will be reduced and not the cooling capabilities of the engine.
 
#31 ·
Calson said:
The addition of factory radiator fans has also helped when going up long grades where the heat output is the highest and there is less air moving through the radiator fans.
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Radiator fans have been standard equipment on cars for a long time. Early cars used fans driven by the accessory belt. Later, heat sensitive fan clutches were used to save fuel. The more recent iteration is electric fans that save even more fuel plus they add a lot of air flow at idle to allow air conditioning to work well in very slow or stopped conditions.
 
#32 ·
I had the opportunity to drive into the lower mountains near me and on a quiet freeway, did about ten consecutive 60-85 MPH near-full throttle acceleration runs on a 6% uphill grade, with each acceleration followed by very light throttle to fairly quickly slow back down to 60 MPH before immediately accelerating again. Each acceleration phase was probably around 8-9 seconds, with about 10-12 seconds of deceleration to get back to 60 MPH.

To recap, we have a hybrid XLE so it has the NiMH battery. The gauge showed six bars at the start of the test and ended at four bars but the 10-12 seconds in between acceleration runs seems to be enough to partially recharge the battery. The power flow was showing the battery to be recharged continuously by the ICE during the deceleration starting after the second acceleration. There wasn't any discernable decrease in acceleration on the final run, and within a minute of the final acceleration, the battery was back at six bars though I was still climbing at about 65 MPH.

I can't imagine needing even ten consecutive acceleration runs like this so I'm satisfied our hybrid will work fine on our upcoming road trip through the Rockies in August. I'd expect the Prime to be even better performing with the significantly larger reserve even when running in auto mode to deplete the battery as much as the battery management allows.
 
#33 ·
Chris B. said:
I am considering buying a 2023 RAV4 Prime but am concerned about power for passing during long uphill drives. We frequently drive from the San Francisco Bay Area to Lake Tahoe in CA. The steepest part of this drive is from Auburn to the Donner Summit, an elevation gain of 5900 feet that takes about an hour at 65-70mph. There are only 2 lanes, and every few minutes we encounter and need to pass a slow-moving semi tractor-trailer in the RH lane.
Twenty years ago, I hated the engine noise and lack of passing power when making this climb in our 160 HP Honda CRV. Will the RAV4 Prime sustain those speeds, AND have power to spare when I need to pass semi tractor trailers?
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Yes, definitely. I just drove my new Rav4 Prime SE across the Mojave Desert on I-15. There are 2 very long hill climbs between Las Vegas and Barstow, one of them being 15 miles of continuous 4% to 6%. The car climbs effortlessly, with plenty of extra power to get around slow moving trucks and RV's. It's not turbocharged, so there's going to be some loss of power at elevations above 6,000 feet, but the 180 hp MG2 motor can compensate for that, especially if the battery is near full when you start the climb.
 
#35 ·
I just took a round trip to Vermont, 150 miles, 10-11k elevation gain (depending on direction), while towing a small travel trailer that weighs ~2100 lbs. On the way there I averaged around 23mpg and did not use up significant amounts of EV miles. On the way back I did use all 30 EV miles and ended up averaging ~26mpg. I had no problems merging into traffic and getting up to speed quickly, nor going up (or down) significant hills. There was one hill I felt a bit better going maybe 5 miles under the speed limit but that was the only one. So I would say the R4P has plenty of power for sustained hill climbing.
ETA: the longest significant hills were one section 9.2 miles long, 3.4% average grade, the other 4 miles long, 4.7% average grade.
 
#36 ·
This week we went to Jackson, WY over the Teton Pass. Posted 10% grade on both sides of the pass. I used Hybrid mode, and there were a few sections where the power meter was near maximum, and the revs bumped up, but the gas pedal never reached the floor, and it never dipped into the EV capacity.

I like that the eCVT eliminates all gear hunting one gets from a standard transmission.
 
#37 ·
A little off topic but took 23 Rav4 Prime I got in August to Eldora Colorado for the first time from Boulder. 25 miles and 3800 foot vertical gain. Started fully charged. Ran out of EV about 2 miles and 600 feet from top. When we got to town coming home we had built up 10 miles of range, and had 1 left when we got home.

Not sure how much gas was used but needle didn't move from start to finish just over 1/2 tank, so effectively round trip just under 50 mile range, on par with what flat drive at similar speed would have been.
 
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