How to drive up steep mile-long hill?

I'm guessing with a 2010 Prius, your traction battery is significantly degraded to the point that it quickly drops to minimum state of charge and isn't helping with the climb. So you're making a steep climb on the gas motor only, and 20-25 MPH is not in the gas motor's sweet spot for torque. That's why you cannot accelerate further. Low speed torque needs to come from the electric motors, so your only option is replace/recondition your traction battery.

 

if it were me, i would do the speed limit in the right lane and ignore everyone else.

 

You should not use ECO mode to climb hills. Just drive the car normally and don't be so drawn to getting the best MPG.

 

Another thought: do you have a Check Engine light on? A clogged catalytic converter will drastically reduce available power.

 

How much elevation gain does this hill climb? From the problems you mention, it sounds like more than 500 feet.

If you are pushing the pedal all the way down, there should not be any climbing speed difference.

 

+1 EXACTLY.

I have no idea why people are afraid of pushing the pedal down. I've seen lots of people buy super powerful vehicles and drive them by basically just idling it up to speed. If you're using the power of the vehicle properly, ECO and normal will be exactly the same. There is no reduction of power in ECO mode, just a remapping of the pedal.

Floor it and see how fast you can or want to go.

My Gen-2 has climbed Pikes Peak many times, never limited to 20mph and something tells me this is slightly bigger than your hill. Similarly my Gen-2 climbs Vail pass which has 9% grades and goes from 8200ft to 10,600ft. Or Hoosier pass which is done 20+ times a year with a loaded vehicle, 4 miles and 1000ft+ gain starting at 10,500ft above sea level. I've also done this trip many times with a dead hybrid battery. Meaning throwing codes and cleared. It still made it up just fine at 50mph to 60mph.

Push the pedal to the floor.

 

My 2010 (same year, different trim as OP's car) did each of these too, though had to stop at Devil's Playground below Pikes Peak due to a road closure. (So we hiked up the rest of the way.) If a Gen2 can do them, then any Gen3 in proper working order ought to climb them even better.

And no roads in Oregon are at such high elevations, so the engine shouldn't have the high-Colorado, thin air handicap.

 

Yeah, my 2011 does 40-50mph up a bunch of Colorado passes. I floor it and listen to the 1.8 purr like a lion lol. It's going to be loud!

 

How do you drive a Prius up a steep hill, Push the right pedal......

 

^ Plus one on this. There's not much you can do, a hill is a hill.

Also, "ECO" on or off, doesn't really make any difference; you can get the same throttle response either way, just takes more gas pedal travel with ECO on. Personally I used ECO for about the first 6 months of ownership, got tired of the excessive pedal travel, switched it off, and noticed no difference in mpg, just a more "natural" pedal response.

If I recall correctly @bwilson4web weighed in on the best way to deal with long uphills, a few years back too. It was basically to be in the right lane (truck lane (aka slow lane) if available, and even stay under the speed limit, say by 10 mph (if traffic isn't hassling you).

A couple of our grandsons are now going to a school at the top of a long/steep hill. Thankfully it's not often we're called on to run up there. I find it a little frustrating: city planners plunking subdivisions and various institutions up steep grades are contributing to excessive fuel use, engine wear-and-tear, and pollution.

Coming back down a steep hill is a hassle too: hard on brakes on any vehicle, and with vehicles like the Prius can get you into borderline overcharging issues, requiring the need to use B mode. The latter's likely not needed, but still: hills take a toll on the Prius battery up-and-down, I think.

 

IMHO, it depends on the speed limit, as it is possible to go too slowly up a hill. To make an extreme example, driving 1 mph up a hill is basically stationary, and most of the energy used is going to produce the torque required to keep the car from rolling back down the hill, which is basically lost as heat in the motor windings. Going 2 mph doesn't take much more torque than 1 mph but you get to the top in half the time, so it's basically twice as efficient.

My instinct tells me 30-40 mph is about the sweet spot for a 10% grade, as it's about as fast as you can go without bringing in aero drag, or revving the ICE out of its most efficient range which tops out at about 3k RPM. This is based on climbing a rather steep, long hill with a ScanGauge For what it's worth, when climbing the same hill in my F150 the slower I go the more the transmission has heated up by the top.

Another data point with relevance to the OP: On a different 10% grade with a higher speed limit, 60 mph is about 4000 rpm with no draw from the battery (and I make no claim that that is efficient). It seems a hill would need to be extremely steep, on the order of a 25% grade (think "mountain hiking trail") to limit a Prius to 20mph with your foot to the floor. There's very few roads this steep, but they do exist.

 

I'm guessing OP has something else wrong with her Prius. I drive in the mountains often and have gone up very steep hills. There hasn't been a single road that I would top out at 20-30 mph over a mile section. At least not where everyone else is doing 40-50 mph. There are times where I "choose" not to push my engine because I don't like to put stress on it, but the car would respond if I pushed it.

When I want that extra bit of power, I always turn off the AC. That's a trick I learned when I drove my 100 hp 1NZFE Scion xB.

 

This would have an effect if the A/C compressor was belt driven off the gas engine, which in the Prius is not the case.

 

No matter how the A/C is powered, it's certainly not a "free lunch".

 

Are you saying there ain't no such thing?

It wouldn't surprise me if the ECUs automagically backed down the compressor power when you demand maximum acceleration. I don't know it for a fact though. There were some older cars that would release the compressor clutch under similar circumstances.

-Chap

 

Back in the eighties, I would notice if the AC came on (in one of our Accords) while accelerating, it felt like someone threw an anchor out the back, lol. Looked into and installed one of these:



It's basically a vacuum switch, requires high vacuum to keep the circuit closed. Under moderate to heavy acceleration, vacuum in the intake manifold drops, and with this switch spliced into the AC compressor power wire, it switches off the compressor momentarily, say during hill climbs.

Yeah the Prius AC is less imposing, but it's not a perpetual motion machine, lol.

 

Thanks for the info. There's one steep mountain climb while leaving Las Vegas where I would turn the AC off. At least I can stay cool now.

 

About all you can do in a Prius is build up a "head of steam" before starting the climb. The gas engine in Prius is always in "top gear" and cannot "downshift" like a traditional car, The electric motors make up for the torque that would be available in a typical car when you downshift, but when the traction battery is spent, all you have left is gas power, and if you are too slow for the puny torque of the gas motor to maintain speed, there's nothing you can do but slow down.

 

Well ... the "top gear / cannot downshift" part is a bit of a stretch ... there is a transaxle between the engine and the axles, and just like any transmission anywhere, it can vary the ratio between engine speed and axle speed over a good wide range; that's its job. That it does part of that using timed electrical pulses rather than meshing gears is neither here nor there.

When you hear the engine whining away at high RPMs and the car is moving slowly, that's how you know it has "downshifted", no different there from any other car.

The main thing is just that the engine is putting out top power in that situation, and the Prius engine's top power isn't very high.

In this thread, I wonder if it's also possible that the OP's car has an issue resulting in even less power than normal.

-Chap