Mountain Driving: HV or EV

Douglas Firs

Douglas Firs

Member
I've seen this topic come up in other threads, but I'm not sure the jury is out on this yet. Have you had a better experience driving through mountains in HV or EV?

I'm not interested in what's most efficient, but rather which you have found more powerful. My experience zipping through the hills outside of SF (with +1200ft elevation gain over 4 miles as the biggest climb; 45mph) is MUCH more enjoyable in EV. Car is very sluggish in HV. We're going to Tahoe in a few weeks and if we have electrons to spare when we hit the mountains, I'll be going into EV for some of it. Not sure how it will compare with driving through the gentler hills in the Bay Area.

Are there factors like speed, grade, distance, curves, etc that matter for either?
 
I have only driven on out of town trips in HV with a full or nearly full charge, so I have no experience with EV on hills.
On significant hills (grade not posted), I had plenty of power and no “angry bees” high engine revs. The ICE revved up to what I would call a low-medium speed that was somewhat like my old gasmobile downshifting out of high or OD. It wasn’t unpleasant at all and I had no loss of power.

So my Clarity drives so well on hills that I see no need to switch to EV just for a hill. My Clarity seems quite capable of switching between all the power flows by itself to give me the best economy, power, and comfort for any situation on the Highway.
However, I suspect very high speeds, heavy loading, and/or depleted charge might not give such great results.
 
We often drive over what is the foothills of the Appalachians, between N GA and the Knoxville area. It’s around 100 miles. We usually drive EV until EV range hits 10, then switch to HV. I’ve noticed no appreciable difference in power. All done in SPORT, if that makes a difference.
 
I do wonder if there's something psychosomatic going on. I really do feel like EV is zippier, but I suppose I'd have to do a blind "taste test" to know for sure. Hence my interest in people's subjective/real-world experiences vs. what I *should* be experiencing based on the underlying mechanics of the car. Curious!
 
My .02.
I always think the electric motor is stronger but if you exhaust EV range it will be less pleasant. So due to nature of mountain driving probably always more than 40-50 miles away (or more), I start out in HV mode, and I prefer sport mode. Sport just remaps the accelerator but I like that when going up hills.

Mountains *can* exhaust EV range even in HV mode. Long press HV works if EV gets too low. Say below 10 miles estimated EV range. HV recharge mode works when driving through mountains (albeit very slowly). Don't bother with long press HV (HV recharge mode) at all unless EV goes down to 10 or fewer miles estimated range.

Technically no tuning is required of course. You can just drive it. But I find having some EV range available, especially for hills is way better.

-Dan
 
Dan Albrich said:
My .02.
I always think the electric motor is stronger but if you exhaust EV range it will be less pleasant. So due to nature of mountain driving probably always more than 40-50 miles away (or more), I start out in HV mode, and I prefer sport mode. Sport just remaps the accelerator but I like that when going up hills.

Mountains *can* exhaust EV range even in HV mode. Long press HV works if EV gets too low. Say below 10 miles estimated EV range. HV recharge mode works when driving through mountains (albeit very slowly). Don't bother with long press HV (HV recharge mode) at all unless EV goes down to 10 or fewer miles estimated range.

Technically no tuning is required of course. You can just drive it. But I find having some EV range available, especially for hills is way better.

-Dan
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Yeah, I am DEFINITELY not going to exhaust the EV. We did that on purpose to see what would happen and the engine really strained. We had to go up incredibly steep San Francisco hills on our way home and got the scary revs with not a lot of power. I am a bit worried that the combination of distance (200 miles) and elevation gain (6200 feet) on this trip will exhaust the EV even in HV the whole way. But it sounds like we could do HV recharge to mitigate. Only one way to find out!
 
I drove from Eugene to Tucson via the eastern route (no interstates). That drive is about 50% repeated hills and mountains. More than 1200 miles each way. Clarity did awesome. I did *need* to use long press EV to keep EV range at some points. It's the nature of repeated hills; there's no chance for EV range to naturally recover as it tries to do. i.e. on a flatter route, I may of gone all way mostly retaining EV range and never long-press. But the hill after hill after hill, you get the picture.

Edit: And as I say, if known exceed EV range, start with HV mode on from the very beginning. Guard against losing EV range if big hills and mountains are on your route. I see no downside in doing so. i.e. If my range starts at 38 miles, do not wait for it to go to 35 and then press HV, flipping press HV before you leave your driveway. To help myself I put a sticky note on D button that says "HV?" so I always start out in HV mode on a trip. A trick I learned from others here in these forums.
 
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Sorry I can't help much with this question, as I'd have to drive 10 hours to find the closest thing to a real mountain. :)
 
Fast Eddie B said:
Once we hit HV, our Clarity will pretty much hang onto it’s EV range. It will drop by a few on uphills, but regain it on downhills.
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What's the farthest you've gone in HV at highway speed? I'm wondering how much I'll lose over the course of this trip when in HV mode. It's 200 miles total. 114 will be almost entirely flat, and then last 86 goes from 0 - 6200ft.
 
My 2 HV trips were 250 miles each with two significant hill climbs each. I only lost about 10 miles of EV estimated range and that included two stops where I forgot to hit the HV button and drove a couple of miles on EV.
 
Douglas Firs said:
Car is very sluggish in HV.
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The traction motor can produce 121 horsepower when operating on battery power alone. When the ICE is turning the starter motor/generator to supplement the battery power, the traction motor can produce 181 horsepower. When HV is selected, the Clarity can proceed using EV power if it deigns that adequate, or it can start the ICE to deliver more power, as needed.

I can't understand why you would feel sluggish response from HV unless you're really talking about HV CHARGE, which saps some of the ICE's power to charge the non-contributing battery.
 
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Driving through a mountain range in HV mode going 60+ mph I quickly burned through 25m EV range going uphill, then gained ~12 going downhill only to quickly burn through it again going uphill. Overall power felt good, but obviously it was noisy compared to EV only... which wouldn't have gotten me very far ;)

No issues with power though even with EV @ 0 it still had some battery to give when passing big trucks on uphills and small passing lanes. I had the car info up on the main display so could see how it kept giving battery -> wheels along with the gas engine for most of the drive.

Only HV Charge mode should really make it sluggish as then you are gas only instead of Hybrid.
 
Douglas Firs said:
What's the farthest you've gone in HV at highway speed? I'm wondering how much I'll lose over the course of this trip when in HV mode. It's 200 miles total. 114 will be almost entirely flat, and then last 86 goes from 0 - 6200ft.
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I did an 800 mile trip with no charging from Salt Lake City to Las Vegas and back, all in HV mode. There were several mountain passes which reached altitudes of over 6500 feet. I left Salt Lake City with 62 miles of EV and completed the trip with 17 miles. I never used HV charge mode; don't see any sense for it. The speed limit was 80 mph for over half the trip with 70 mph being the lowest.
 
insightman said:
The traction motor can produce 121 horsepower when operating on battery power alone. When the ICE is turning the starter motor/generator to supplement the battery power, the traction motor can produce 181 horsepower. When HV is selected, the Clarity can proceed using EV power if it deigns that adequate, or it can start the ICE to deliver more power, as needed.

I can't understand why you would feel sluggish response from HV unless you're really talking about HV CHARGE, which saps some of the ICE's power to charge the non-contributing battery.
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We were not in HV Charge so... ¯\_(ツ)_/¯
 
Douglas Firs said:
I do wonder if there's something psychosomatic going on. I really do feel like EV is zippier, but I suppose I'd have to do a blind "taste test" to know for sure. Hence my interest in people's subjective/real-world experiences vs. what I *should* be experiencing based on the underlying mechanics of the car. Curious!
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I wonder this too. Logically, the car should be putting out the same power at the same point on the power meter, whether the ICE is running or not. I wonder if folks are correlating the noise of the ICE to expecting more power, when in fact they are getting the same power - or alternatively, when the ICE revs higher than you consider comfortable, the natural inclination is to back off the accelerator, resulting in less power and acceleration. So, I agree - is it the noise of the ICE that skews the "feeling" of relative power, and not the available power itself?
 
Douglas Firs said:
What's the farthest you've gone in HV at highway speed?
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1000 miles in 2 days with no recharge. Still had charge left as I neared the end of my trip--winter, heat on, driver only plus Christmas presents and luggage, speed under 70 mph., ACC generally on.
 
Although the engine on the Clarity can directly couple with the drive train between about 45 to 65 miles an hour, normally propulsion comes from the 181 hp traction motor. The battery can provide up to 121 hp and the engine generator provides up to 60 hp. In HV mode, the car attempts to maintain the battery charge, but will borrow as needed for acceleration and upgrades.

There seems to be a lot of variation in Claritys and how they behave (noise, sluggishness, etc.). On smooth pavement, my Clarity Touring is very quiet in HV mode at 75 mph. There is absolutely no wind noise and I cannot hear the engine. Course pavement results in the expected road noise. I find low speed driving in HV mode (battery depleted) to be far less refined. The engine revs are quite audible. As a result, I always switch to HV mode when driving at highway speeds to save the battery charge for low speed driving.

The longest drive that I have made was a trip from Florida to Ohio and back in 2018. The total trip distance was 2032.2 miles. I fueled a total of 8 times and used 45.8 gallons. Overall mileage was 44.4 mpg. If I subtract out the approximately 50 miles that were driven in EV mode, the gasoline mileage was still a very respectable 43.3 mpg, as calculated by actual miles driven and fuel used. The trip computer overestimated the fuel economy by nearly 10%. The drive included the WV turnpike through the Appalachian Mountains. During the drive I kept the battery charge at about 50%. I never felt any sluggishness.
 
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