Just got my Clarity Plug-In a couple days ago and I have an efficiency question

Agreed. While highway does use the battery faster it is because of wind resistance and no regenerative braking happening. I use EV mode all the time unless I'm going on a long drive beyond the capacity of the battery. At that point I selectively use HV to have it run only one time and when battery capacity matches my destination distance I go back to EV.

I'm lucky enough to be able to plug up at work with 220v. I only worry that I'm doing alot of charging from the same point up twice a day and the effects of that long term.

 

Where on the display does the gear symbol show up? I've not seen it.

 

In the energy flow diagram. At the junction of the energy from the battery and energy from the engine you will sometimes see a small gear icon appear.

 

Personally, I think those among us that spend a lot of time switching between modes are just wasting their time. It is stepping over dollars to pick up pennies. If your goal is to minimize energy usage, either, or even both, battery and gas, just slow down. Drive the speed limit EVERYWHERE! That one thing alone improved my mileage in my last 2 cars by 15%. I am always amused when driving on the highway at the posted speed limit and a Prius passes me doing 15 mph over the speed limit. Why did he (she?) buy a fuel efficient car if they’re going to drive like a maniac?

For me, I always use electric only until the car switches automatically to hybrid. I have never even felt the accelerator detent. In my regular routine driving, the only time I use hybrid mode is the return trip from work. It’s 37 miles one way to work, so roughly 10 miles of the return is still on battery. According to the mileage ratings, that equates to about 5/8ths of a gallon used per round trip to work. With three trips to work since my last (and only) fill up, that would mean I’ve used 26% of a tank. Corresponds to the gauge indication of 3/4s full.

As always, your mileage may vary, literally. But switching modes from EV to HV to HV Charge to try and outsmart the onboard logic just doesn’t make sense to me.

 

@Tailwind You can certainly let the car's logic do its thing and just drive without using the mode buttons - that's the beauty of the Clarity, it just works. However, it seems that someone else who has a similar distance daily commute as yours might benefit from changing to HV mode if there is a mix of both freeway and city driving. Is your home very close to the freeway, or is there still some local driving? If there is some city driving after you get off the freeway, switching to HV mode while you are on the freeway on the return journey can preserve enough of the battery charge so that last stretch of city driving can be done in EV (pretty much what @Dana Mitchell described in his comment). And you may find that you will end up using less gasoline overall if you only use the ICE during freeway driving while doing all city driving in EV mode, mainly because battery charge drains so much faster at highway speeds, whereas city and stop&go driving uses more gasoline.

 

Unless I've missed it, I didn't see the affect of the electric heater in any of the efficiency calculations. So how does that figure in the numbers?

 

Agreed. There are some Volta charge stations. They are free. http://voltacharging.com

 

I can tell you this much, you'll never see 47 miles EV at 70 mph.

Depends on usage Tailwind - if you are facing longer than commuting distances (like my recent 600+ mile round trips) where there are advantages to preserving EV distance at the destination - all HV to destination; EV at end point; HV/HV Charge back to home if you'll need EV at that end...

to each their own...

 

In general, PHEVs are designed to allow the battery pack to provide as much as possible of the energy for driving, until the battery pack drops to a certain level. Below that, the car uses its gas motor to power a generator which keeps (or at least tries to keep) the battery from being further exhausted. IIRC in the Volt that level is 30%. I dunno what it is for the Clarity PHEV, but presumably it's approximately the same.

Turning on "Charge" mode on the Clarity should increase the level at which the car tries to maintain the battery pack. I'd be interested in seeing if someone can give us an accurate figure for that increased level; the percentage of full charge. For most cars I'd say just look at the instrument panel and see what the gauges report for the charge level, but there have been so many reports of the Clarity reporting range or charge level which is wildly off that it's obvious those gauges are not reliable.
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I care more about engine noise than efficiency, but this simple guideline works well for both:

- if full round trip is within EV range, just drive and don’t change anything.
- if more than EV, then HV regular for freeway, EV for non-freeway.

 

This is exactly what I do. Within range, I drive in eco mode, so all EV easily. Switch to normal if I need more boost. On a longer trip, switch to HV for the highway portion and maximize range of battery in city portions. Works perfect - ended up with an average of 3.5l per 100 km on a 250 km trip last week.


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Kendalf, you hit the nail on the head and I agree with everything you said except isn’t the EPA rating higher for the city than the hwy? 44 vs 40?

 

Right. In fact, that ought to be put into a FAQ somewhere.

No need to keep obsessively switching between HV and EV mode, but if you're going to drive beyond the EV range of the Clarity, then it makes sense to switch to HV mode for some or all of the highway driving, and preserve the EV range for where it will do the most good, which is at lower speed and/or stop-and-go driving.

I'm assuming here that the goal of most Clarity owners is to make as many miles as possible EV miles, rather than gas-powered miles. That also means that on the way back during a trip that will (or is likely to) go beyond the EV range of the car, switch back to EV mode as soon as you're sure you have enough EV miles to get there, even if you're still on the highway.

* * * * *

Now if your goal, gentle reader, isn't to maximize the EV miles in order to minimize the amount of gasoline/petrol used by your car, if you bought your Clarity for a reason or reasons having nothing to do with reducing the amount of gasoline you burn, then this doesn't apply to you.
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You're right!

 

Hmmmm...I knew I read all this somewhere earlier in the thread...

 

I did 53 miles yesterday, virtually all highway, in EV mode at 50-55 mph.

When I got in the car on Friday morning, it said I had 51 miles EV range. It is about 3 miles through neighborhoods until I get on the highway, then 34 miles to the airport at 55 mph. Temperature was 38°F. When I returned yesterday afternoon, temperature was around 60°F and car said it still had 14 miles EV range. After 16 miles on the highway on the return trip, the engine came on for the first time.

 

Is this your first EV car? We have had a Nissan Leaf for 7 years. (2 different cars). Here is what affects range in an EV. Hills and/or inclines. A/C on. Heat on. Speed. When you are driving, you may not be aware of inclines, but the battery knows. Our Clarity typically shows a range, after charging, of about 54 miles. Freeway driving at 55-65 mph does not seem to affect it much. Driving the canyons in Los Angeles is interesting. Uphill the range takes a dive, but it recovers on the way down.

 

In actuality, electricity is still more efficient than using gas period. I can still get close to 100 mpge driving highway miles. However, the problem with electricity is the energy storage. The vehicle has a 17 kWh battery, and after draining it to 9-10% and recharging, it appears we can use 14.3 kWh of this. 14.3 kWh of energy is equivalent to only .44 gallons of gasoline (a gallon of E10 has 32.78 kWh of energy). After looking at those numbers, it's clear why it is best to use HV for sustained highway driving. If you can complete your trip, even with highway driving, within your EV range, then it is still best to use electricity. At some point down the road battery prices will drop enough so that you can get a 75 kWh or 100 kWh (like those found in the Teslas) for a more practical price. At that point, highway driving with electric would be more feasible. We aren't there yet.

 

Maybe our case is unique. Our house has solar power. It costs nothing to charge our EV or PHEV. There are studies that show that EV is cleaner than gas or hydrogen. Bottom line: Use EV whenever you can until it runs out.

 

from the UK-based Transport & Environment