Can't get up the moutain

I don't recall when that was. All I know is, I had no problems going to Georgetown, CO from Longmont last September and my Brother-in-law took my Prius from Longmont to the TOP of Rocky Mountain National Park last December with three people in the car (all of whom are on the heavier side) and NO problems. It is almost 14,000 feet at the top. He said the battery got low, but there was still enough power to keep going. My guess is the air resistance up there is almost negligible. He took the car down the backside, through Granby and reported full green battery with very little engine running all the way down the mountain.

Don't forget, most mountain climbs are not full ascents, but are sequences of long ascents followed by shorter descents. The batteries charge on the small descents, and give you energy for the rest of the climb.

It's actually quite difficult to drain your Prius to the point of all-gas running. Even the curves on a switchback give the Prius a chance to make some electricity as you let off of the accelerator.

Also, if you live at the top of a mountain, you charge on the way down in the morning, and drain on the way home.

If you live at the bottom of a mountain, you will be charged from the night before, drain on your way to work, and charge on the way home.

If you live at the base of a mountain, and sit with your Prius in the "key on" position until the battery is very low, and THEN try to climb a mountain, you may have a problem.

Nate

 

Well, it's not 14,000 feet, but I had no problem climbing Mt Lemmon (9,000) right outside of Tucson. This was fully loaded: 4 people and luggage in back.

Thanks,
Shawn

 

Also remember that the Prius (THS 2 especially) can run just fine with no contribution from the battery. Climbing mountains should be no problem as long as there is gas in the tank.

 

This doesn't make any sense to me. Worse case scenario is that you pull over for some sightseeing and let the engine run and recharge the battery for five minutes. Big deal. How often does one need to go up a hill so big that the engine actually needs the battery assistance to get up it? How many such roads are there that are that steep? I guess I better buy a hummer so this doesn't happen to me!

 

This sounds like something that will end up being urban legend. About the only way I can see to totally discharge the battery, would be to do some massive kamikazee run up the hill. I took mine through Eisenhower tunnel on I-70 las February. The battery never dropped below 1/2 on the car, and I saw a full "green" battery for the first time ever, since I bought my car. Going back home, I had 400 wh of little yellow "E"s on my consumption screen, and once again, a full battery. I let the cruise control maintain the posted speed limit going up the hill, and the car never dropped below the limit.

 

The battery drain rate has got to correlate to some combination of vehicle load, rate and length of ascent, and vehicle speeds. Our local Appalachians are nowhere near as high as the Rocky's but I made a trip across Route 33 from Harrisonburg, PA a few months ago and the battery was down to about 1 or 2 pink bars by the time I crested the top and started back down. I don't know what the elevation change was since I didn't have GPS at the time.

I never worry about sitting in traffic but I wonder what kind of wear and tear or risk of overheating you would put on the ICE when running it for more than the few minutes that it accustomed to -- not to mention the thinner air at those elevations.

 

The height of a mountain has less to do with the steepness/ amount of climb than it has to do with the air density, and therefore the oxygen content, at that elevation. On a hot day, with a full load, and the A/C on high, the climb will be even worse. Even the V8's start to hurt coming over Eisenhower tunnel. The best cars are turbos and supercharged... or maybe electric, since there is no altitude penalty. The only advantage at altitude is the lower air resistance, but it doesn't balance out. Also, the temperature stays lower at altitude, so the heat is not that much of a concern.

Eisenhower tunnel is at 11,158 feet. By the way, I checked my facts, the top of Trail Ridge Road in Rocky Mountain National Park crests at 12,183 feet, I thought it was well over 13,000, but either way, it's awfully thin up there, and my brother in law reported zero issues going up and over.

Nate

 

Thing is, there is a point where the engine is simultaneously putting power to the ground, generating electricity for the electric motor to assist, and also even adding charge back TO the battery.

It's a sweet system.

 

The only report I have seen that showed the car slowing drastically was the Motor Trend article where they said they tried to run it over 90MPH through the desert and Cajon Pass, and that they had to slow down under 55 for a while to let it charge.

 

It's B.S.

I personally drove across several mountains on my 4,100 mile trip across country from California to Michigan last summer.

The battery bar turns PINK, the engine revs pretty high, but the Prius had no problem climbing long mountain passes. I even passed a semi or two on the way up. A/C was on too.

It's a lot more fun coming DOWN a mountain. It's the ONLY time I ever used the "B" mode.

 

This is my first post after lurking on Priuschat for some time. I recently purchased a salsa blue package 6 in Muskogee, OK back in late Feb.
Anyway, my wife and I took the car up to Santa Fe ski area fully loaded 3000' vertical on snow covered roads going 20-40mph with no problems. There was no problem though the battery did run down to 1 pink bar. I began to wonder if I could take the car over a 5000' climb on some highways like I-70 in CO, I-80 east of Sacramento or I-17 north of Phoenix. There were several posts on Edmund's Prius forum that suggested that the battery would run so low that the 'turtle' mode would limit the car to < 40mph. I'm guessing that their posts were based on experience with the first generation Prius, not the newer one. Anyway, your posts counters theirs quite nicely. BTW, I also get the impression there is a lot of anti-prius posters on Edmund's too.

regards,
Jim

<div class='quotetop'>QUOTE(priusham\";p=\"71261)</div>

 

<div class='quotetop'>QUOTE(naterprius\";p=\"71241)</div>

Nate:

When I used to live in SLC, I frequently took I-80 which takes a long climb past Parley's Summit before you turn off at Kimball Junction and head down into Park City and Deer Valley. I have friends living there, in summer I did a lot of mountain biking and in winter a lot of skiing in the area.

For some reason, most of the vehicles pulled over in the breakdown lane near the Summit, steaming like crazy, where giant V8 pickup trucks and SUV's. There are black marks on the breakdown lane where a few have even caught fire, always good for a laugh.

Most of these drivers like to show off how much power they have, so they keep it to the mat with the A/C on Max. In most giant SUV's the cooling system is the weak link and you eventually overheat.

I had my Canadian market 1984 Ford F-150 down in St. George for a few years and one summer in SLC. That was brutal as it didn't have A/C. However, it did have a custom made 5 row rad, a 160 thermostat, Edelbrock intake, Moroso 2 inch 4 hole spacer, Edelbrock 500 carb, custom dual exhaust, and no emissions.

I used to have a lot of fun roaring up the Summit at 85, blowing away every SUV and pickup in sight. Also Route 40 north of Heber City, there is a very nasty grade there too.

My coolant temp never went over 195 on the climb, and my trans temp never over 175. It really does depend on the cooling system and oversized auxiliary transmission cooling.

This issue is way overblown. Yes, there are a *lot* of anti-Prius posters especially supporting Chevy and Dodge trucks, and they make up a *lot* of this s***.

If you want to see problems climbing grades, watch people drive Pikes Peak outside of Colorado Springs. I've seen proud Chevy owners keep their foot in it the entire climb up, stop at the top, and WHOOSH they boil out.

 

Is that salsa blue a two-tone?

 

<div class='quotetop'>QUOTE(Ron Dupuy\";p=\"73906)</div>

Ooops, so much for remembering fancy names for simple colors; Salsa red and Seaside pearl. I'll just call it blue - lot's simpler.

Yes there is all sorts of car carnage up the big hills including some in my own family such as the 1978 VW squareback which lost fuel injection. Just go up Mount Washington and you'll see all the stops for those blowing steam out their radiators.

regards,

Jim

 

<div class='quotetop'>QUOTE(jimdaph\";p=\"73847)</div>

Put down that salsa son, it's gone moldy! Salsa's s'posed to be red!

I have a salsa red myself, but would have preferred Seasside pearl.

 

I will say that when I told my in-laws that we had bought a Prius they said 'that is the car that could not make it up the hill to our house'. They live on top of a mountain in Asheville. The last 3/4 of a mile is an unpaved road at 12% to 14% grade (steeper than anything you would find on a paved road). They said at least two Prius have tried to get up the road and failed. Almost any other car can get up the road with no snow. I would think that indicates that either the lowest gear on the Prius isn't that low, or the engine doesn't have that much torque. We may drive there this summer and I am looking forward to the challenge of getting our car up the hill.

rickdm

 

Rickdm keep us posted. If you can't make it up the hill it will be the only first hand reply that I have ever heard of which showed 2G prius is lacking. The rest I have read are all speculation as far as I can tell and most likely urban myths.

 

This whole thing seems unlikely. Physics was over 10 years ago for me, so someone should correct my errors, but let's see:

Consider the torque of MG2 *only*, as if the car is in EV mode, or the engine isn't running. The car can only be stuck on the hill, unable to climb, if the car cannot apply sufficient torque at 0 MPH to accelerate the vehicle.

Suppose the Prius weighs 3300 pounds -- curb weight plus a few hundred pounds for passengers and whatnot. If the hill is a 14 percent grade (7.97 degree slope, since arctangent of 0.14 is around 7.97 degrees) then acceleration due to gravity is 462 pounds. So gravity is exerting 462 pounds of force backwards on the car, trying to push it back down the hill. To climb the hill, you must push forward with more than 462 pounds of thrust.

MG2 is capable of generating 295 foot-pounds of torque. This means if you connect MG2 directly to a wheel with a one-foot radius, it will be able to push with 295 pounds of force. The Prius, however, uses a reduction gear to connect MG2 to the drive wheels. Graham's Prius page puts that ratio at something like 3.905 for some generation of Prius. This reduction gives the axle 3.905 times more torque but it turns 3.905 times more slowly than MG2.

So this means from 0 to 1200 RPM, MG2 can generate 295 * 3.905 = 1152 foot-pounds of torque at the axle.

That doesn't translate to 1152 pounds of pushing power, though, because the Prius wheels don't have a one-foot radius. Their radius is around 11.1 inches. This reduces the force available at the wheels to 1152 * 11.1 / 12 = 1066 pounds of force.

With 1066 pounds of force pushing forward and 462 pounds of force pushing backward, the Prius would shoot forward.

So how much of a grade can the Prius handle? If the vehicle weighs 3300 pounds, and we have 1066 pounds of pushing force available, then a grade of 32.3% (17.9 degrees) cannot be climbed using MG2 alone.

How fast can you climb? As speed increases torque decreases, so we'd have to know both force and energy output (foot-pounds AND horsepower) at various speeds, so that's a MUCH harder problem.

I'm not confident enough with my math to suggest anyone's family is lying -- someone else should definitely look over my numbers.

--Spence

 

Oops, wait a minute, hold on. I forgot about TC.

So if the road is made of loose enough material, then ANY vehicle (regardless of torque) with traction control as aggressive as the Prius would be unable to climb that hill.

So yeah, if the road leading up there was paved, there would be no problem. If it's gravel, maybe there would be too much slipping. (Wait, if the road was like that, wouldn't any car just slide back down the hill, if you tried to park?)