prius climbing to 9,000 feet questions

I've driven into and through the Sierra Nevada a few times - the ICE keeps up just fine in my experience. In fact, I've had times where I try to anticipate a long, steep downhill by using as much battery as possible just prior to the peak - but I used too much battery too soon, so it started charging, while still going uphill.

Now, admittedly, I'm not an aggressive driver, and I tend to go easy on the go pedal (I'll sacrifice a few mph going up a hill, I don't feel the need to maintain the speed limit or better at all times). But, especially with the more powerful engine in the GenIII, I doubt you'll have any troubles.

 

Can't really speak for a Gen3, but I have a Gen2 and a couple years ago I took a road trip, West from MN to Yellowstone, South to the Grand Canyon, North to Arches National Park, East to Chicago.

Crossing the Continental Divide twice along with various other changes in elevation, I had only 2 small issues. Both were on I-70 headed East through The Rockies. There was a strong headwind and a pouring rain slowly turning to snow as I gained altitude. With self (obviously), my wife, our German Shepard, our camping gear, and all our luggage, I suspect we had between 700lbs and 800lbs loaded in the car. With the accelerator on the floor, I was just maintaining 70MPH and couldn't seem to get any faster on an 8 mile stretch of road about half way between Vail and Frisco Colorado. Then the same issue again, accelerator on the floor and just maintaining 70MPH between Dillon, CO and the Eisenhower Johnson Memorial Tunnel.

Other than those 2 short stretches of road in those particular weather conditions, I always found I could accelerate easily to pass another vehicle if I wanted.

For that matter, the very next morning after the stretch of road indicated, it was a sunny clear windless day, and the Prius easily made the trip to the top of Pike's Peak. It never once felt like it was struggling on that trip. The MPG on the trip back down was obviously great, and with the regenerative braking and 'B' mode, there wasn't any issues at all with overheating brakes.

 

I've driven mountain roads my whole life
Driving west out of Denver on I-70 into the Rockies you'll find a LOT of vehicles that can't do 75 mph up the steep grades Danny mentioned.
Our Gen III does fine in going well over 10k feet. We manage to do 70-75 mph the whole way. You'll pass a lot more vehicles than get passed.
I love the look on peoples faces when they have the accelerator floored going 65 and a Prius passes them.

 

In very cold conditions and steep grades the car can feel a bit gutless once the battery is drained but I've still never been forced to slow down or not been able to maintain 70mph during the climb. I've been over the Sierra Nevada range many times which is around 8,000ft. ASL and up into the White Mountains which is over 10'000ft. ASL.

 

Slow T, at 9,000 feet, your ICE power will be down to about 60% of normal so the ICE won't be making enough power to cause any unusual wear if you keep your foot on the floor all day.:cheer2:

The two things you need to watch out for is that it will take you a lot longer to pass another car than it would near sea level and to be sure to use B instead of riding the brakes to control speed on downgrades.

Enjoy the scenery and new driving experience and don't worry about the car. 9k feet elevation won't cause any problems except less power.

 

From past discussions, I believe Gen2 and Gen3 handle mountain climbs different. The former does tend to draw down and sometimes deplete the battery, where the latter does not. Gen3's extra power seems to let it keep the battery charged, and mine has topped many mountain passes with the same 6 bars it likes on flat ground.

But this also carries a disadvantage on the downhill. A Gen3 with a mostly full battery has less room to accept regeneration than a mostly empty Gen2, so more gravitational potential gets wasted.

I've taken three different cars to Colorado for vacations. Only the '86 Accord wheezed much, requiring two downshifts on the steepest climbs at 10-12,000 feet. But that was a consequence of its fairly efficient gearing. A '97 Legacy went further before requiring a single downshift, thanks to a bigger engine with shorter gearing that turns it into a fuel sucking pig on flat ground. The Prius' smaller engine had to work harder, but I didn't get to its limit.

 

One minor note, the brake "Bark" may start happening at altitude. It is caused by small air bubbles in the brake hydraulic system passing through the "Brake Actuator". If it occurs, ignore it as it should go away once the air pressure gets back to normal at lower altitude.

JeffD

 

This is theory for me, as MS is if anything flatter than NJ.

While all normally aspirated engines lose power with altitude, electric motors do not. So while a Prius may lose total power with altitude, the part provided by motors is not effected.

(Turbo charged engines can be designed to not lose power at altitude)

 

I've driven my Gen II through 12,000 foot passes, and it did just fine. You won't set any acceleration records, but neither will the rest of the cars along the way.

As for SoC, I found if I took it easy and stayed in the right lane, the SoC stayed on the low side of normal. If I pushed it, the SoC dropped all the way down, making for a slow trip the rest of the way up. Slow and steady is the way to go.

The Gen III should be even better, given the larger ICE.

Tom

 

I took an 850-mile trip through the Colorado Rockies last summer - up and down, 10,000 foot passes, etc.
No problems at all.

 

ICE's lose power at altitude unless they're turbo/super charged. Because the electric motor does not require "air", you should be better off in the Prius than a simple ICE powered vehicle, your overall power loss should be less.

 

But only for a very short distance. Remember that *all* of the energy in a Prius comes from burning gas in the ICE. A very small amount of that energy is stored in the HV battery, which can then be used for a short boost. The total amount of usable energy in the HV battery is equal to just a few tablespoons of gas. Once you use that up, you are back to just a small ICE pulling you up the hill.

Tom

 

This has been my experience as well. The battery power gets used up VERY quickly and you are stuck with a low HP small ICE engine to get you up the hill. Thankfully there is enough power from the ICE to propel you up most standard inclines without a fuss. There is a marked difference in power but not enough to cause trouble.

 

OP should note that F8L and Qbee are speaking from Gen2 perspectives. OP has the significantly larger engine of the Gen3, which doesn't deplete the battery on most hills where Gen2 did so.

Also, Gen3's engine is small only by America's modern 'bigger is always better' mentality. In reality, it is significantly more powerful than the 2.3 liter Ford I bought 27 years ago, and that had all the power that was really needed. It just didn't have the power to pull away from the impatient new 250+ HP beasts behind you on the highway onramp.

 

While this is true I can almost guarantee you that even the GEN III's larger engine and broader torque band will not stop the battery from being quickly depleted on the hills I mentioned.

 

Should you use PWR mode while in the mountains???

 

I have driven my son's Gen II Prius into the Sierra Buttes and over the Sierra Nevada mountain ranges. No problem whatsoever. I didn't notice any difference at all. I haven't had the opportunity yet with my 2011 but can't imagine it's even a consideration. Going to the Sierra Buttes in 6 weeks and am planning on taking the new Prius.

 

Your choice. I don't, even on Pikes Peak.