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Discussion Starter #1
Drove up a very long grade today with cruise control set to 70 mph. PHEV in HEV mode. The battery assisted the engine and it maintained 70 until the battery reached 2%. At that point the engine, without help from the battery, would not maintain speed. I say would not because it was capable, it just wouldn't downshift. It slowed all the way to 45 before it down shifted and accelerated.

On the way back, when the battery reached 2%, I floored it and it down shifted immediately and maintained speed at something less than full throttle. (Cruise is not active with any manual throttle. It will go faster or slower than the cruise setting with any manual throttle.)

At first I thought this a rather poor way to program the car's cruise control. On second thought, however, IC engines are most efficient at relatively low RPM and high manifold pressure, just where it was climbing in cruise control until 45 mph or where I intervened.

That same grade on the way down was well controlled by the cruise control and regenerative braking. I don't think the friction brakes were used by cruise to maintain speed but I don't know for sure.

Interesting way to operate but, I suspect, quite efficient.

The trip was a bit over 200 miles most at 70 mph and produced an indicated 46.4 mpg. This after a full level 1 charge of almost exactly 9 KWH overnight. The geek in me is really enjoying this car.
 

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I've had a similar, but slightly different experience while driving up Cajon Summit in Southern CA. The first time I did this, my PHEV electric range was fully depleted at the outset. I recall that the car struggled to maintain 70 MPH during the steepest parts of the climb and it wandered back and forth between gears frequently. I don't recall how much of the ascent was in Cruise Control though: that road tends to get trafficy and I usually disable cruise when that happens. The second time I did it, I started with a range of maybe 16 EV miles at the bottom, but I had manually switched to HEV mode: the car performed much better, but most of my electric range was gone when I reached the top. And then a really strange thing happened: I had another 20-some-odd miles to go after reaching the summit, mostly flat and much of it highway. I switched to EV at the top and even though I was only showing about 6 miles of EV range, I drove the entire remaining distance in EV mode. Still haven't discovered the explanation for that.
 

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Discussion Starter #3
I wonder if the error in your EV range was caused by the system learning too much from the grade and thus underestimating what you had left.

I'm beginning to think that on a long trip it may be best to use the HEV mode until in EV range of a charge. The little 1.6 needs electric help on a grade.

My last two charges have been 9.0 and 9.4 KWH's respectively. With 10% or so left, the battery has to be 10 KVA plus whatever overhead it allows at full charge to preserve battery life. If I drive around town, I always get 26 or more miles in pure EV. REALLY refreshing to see a company fairly representing performance figures.
 

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I wonder if the error in your EV range was caused by the system learning too much from the grade and thus underestimating what you had left.

I'm beginning to think that on a long trip it may be best to use the HEV mode until in EV range of a charge. The little 1.6 needs electric help on a grade.

My last two charges have been 9.0 and 9.4 KWH's respectively. With 10% or so left, the battery has to be 10 KVA plus whatever overhead it allows at full charge to preserve battery life. If I drive around town, I always get 26 or more miles in pure EV. REALLY refreshing to see a company fairly representing performance figures.
Yes, the 60 hp electric motor really helps going up hills when in hev mode. The ICE is 1.6 but its only ~100 hp because it is an atchison cycle engine (more efficient but less power density). The same 1.6 engine running the Otto cycle puts out ~140 hp.

FWIW

The current ICE is 100hp and the motor is 60hp. I which they were reversed. ICE 60hp and motor 100hp. More hp when in ev mode but still enough ICE for long trips.
 

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The current ICE is 100hp and the motor is 60hp. I which they were reversed. ICE 60hp and motor 100hp. More hp when in ev mode but still enough ICE for long trips.
That would be great! :)

@Mal : you went down to 2% ?? :eek:
 

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I wonder if the error in your EV range was caused by the system learning too much from the grade and thus underestimating what you had left.

I'm beginning to think that on a long trip it may be best to use the HEV mode until in EV range of a charge. The little 1.6 needs electric help on a grade.

My last two charges have been 9.0 and 9.4 KWH's respectively. With 10% or so left, the battery has to be 10 KVA plus whatever overhead it allows at full charge to preserve battery life. If I drive around town, I always get 26 or more miles in pure EV. REALLY refreshing to see a company fairly representing performance figures.

I really don't know what that was about. Maybe the ICE was running in generating mode after I switched back to EV mode at the top and I just didn't hear it. I just noticed that as I continued to drive at 70 MPH for many miles, the EV range didn't budge. I parked that night with an EV range around 4 miles. When I left the next day, it was around 6 miles if I recall correctly.


When I come back down that same route, I've been disappointed at how little EV range I pick up: only a couple of miles at best, while the car is in HEV mode. I did a different mountain drive at Christmas time over "the Grapevine" headed north from LA. The EV range dropped near the summit, but I kept it in HEV mode and unlike my Cajon pass trip which levels out at the top, the trip over the Grapevine is immediately followed by a steep descent. On that trip, I recouped most of my lost EV miles on the way back down, maybe even to the point of having a couple more than what I started with. Of course, I was in HEV mode the whole time so it's not like it was "free".


Regardless of the explanation for what reads on the EV range, I no longer use up my EV miles at the outset of a long trip. I use up a few so that the battery will have room to accept charge from regenerative braking, and then I switch to HEV mode. On the way home, when I get close to home, I switch to EV mode to use up any miles I have left in the EV range. And if I get stuck in stop-and-go traffic along the way, I switch to EV mode for that too. Having that surplus capacity along the way helps when you want a little more power, or have to struggle with stop and go traffic. And it's just as easy to use it up at the end of the trip as it is to use it up at the beginning - well, almost as easy: you do have to remember to manually flip the switch.
 

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Discussion Starter #8 (Edited)
I watch the energy flow for IC operation. At speed it is hard to tell if it's running and, if running, it seems to maximize energy by driving wheels, generator or both as needed. How I haven't figured out.

I think your methods are sound. No matter how good KIA's algorithms are, they can't read your mind. I will do the same.... EV if the trip is short, otherwise EV for some battery room then HEV until in EV range of a charge. I will be really interested in what the battery does in HEV mode starting at 80+% or so.

Meanwhile, gotta buy gas soon for the 4th time in a bit over 2000 miles.
 

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interesting thread. i thought the ice would only fire up in ev mode with hard acceleration. in a previous post someone mentioned running the tank dry to see what the electric motor could do on it’s own. anybody out there ever try this?
 

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When you run out of gas, it goes into a limp mode and limits your speed severely. Eventually when Kia thinks you will damage your battery, it will shut off.
 

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Discussion Starter #11
The low fuel warning is rather ominous mentioning damage to the battery. It came at 22 or so miles left, a bit after the initial low fuel light. Shortly thereafter it took 10.86 gallons so the remaining miles were just slightly pessimistic.

I tried the HEV mode at about 37% battery and it seemed to try to maintain that but when I shut down, I think it switched back to EV and used my 4 remaining EV miles.
 

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The last fill on my HEV showed 30 miles of range remaining, yet topping off showed over one gallon left in tank (likely more than 70 miles remaining). So yes, Kia doesn't want you to run out of gas.

I'm actually hoping to run out of gas and waiting for a good situation to do that safely (with stations nearby). I have several times filled up within a hundredth of the rated tank capacity of 11.9 gallons so I still don't know how much reserve capacity I have in the filler tube or how far I can really go on a single tank. Two reasons I want to know, one to minimize how often I have to buy gas, and two, for better timing of buying gas when I pass by the best price.
 

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With only limited experience (purchased 2/1/2019), I have an extreme down grade from home to work and the reverse to return home. I generally charge at work, because of lesser cost per kWh than at home. My experience is to use as much of the EV mode going up the grade up to the expected miles to return to work and then use HEV mode. And reverse the process on the way to work the next day. Using the EV mode all the way to work giving me somewhere around 4EV miles left. Once a week a make a 170 mile trip with an overnight stop. I charge fully when I leave and the night over. It seems always best to use about 1/2 the EV mode when you start out and 1/2 the EV mode at the end of the trip. I've done this now for 3 weeks. The mileage is at 1300 and according to the Accumulated mileage and MPG as of this time I'm averaging 74 miles to the gallon and have only used the initial fill up, plus about 1/4 of the newest fill up.
 

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...It seems always best to use about 1/2 the EV mode when you start out and 1/2 the EV mode at the end of the trip....
I share your thoughts on this aspect of taking maximum advantage of the PHEV battery, although I haven't reached any hard conclusions about whether it's better to use half up front and half at the end, or 1/4 up front and 3/4 at the end. In my neighborhood, I'm occasionally confronted with significant climbs/elevation changes, and so I kind of like to only use 1/4 up front. That affords some "room" to accept a charge from regenerative braking, but provides ample assistance from the electric motor when needed for a steep or extended climb.


You didn't mention much about "when the ICE runs". The Niro will happily start the ICE and run it for only 10 or 15 seconds any time you demand extra power, such as (perhaps) when making a quick left turn across a busy highway. In my mind, the problem with that is that some Niro owners (esp PHEV owners) might drive in a way that causes the ICE to start and stop several times during an outing, but never run more than a few minutes total, and more importantly, spend all of its time running (and most importantly: all of its time starting) at cold temperatures. There have been at least a few people on this forum who have noticed that the oil seems to get contaminated with gas (they base this on the increased level reported by the dipstick and also by smelling the dipstick). I suspect that at least some of the people who are experiencing that might be driving in a way that tends to start the ICE, run it very briefly, and then let it shut off, maybe several times during an outing. What I'm trying to suggest is that, in addition to the battery management techniques you've described, there is this other consideration that you might want to keep in mind: if you need to start the ICE, try to let it run long enough to warm up at least part way to normal temperature. That way, when it needs to occasionally start and stop after that time, it will be starting at warm temperature, maximizing fuel efficiency, and reducing the potential that it will be introducing surplus unburned fuel (which it needs when cold) into the engine oil.
 

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Discussion Starter #15
I have also worried about the short duty cycle of the ICE. Conventional wisdom is that's extremely hard on an ICE. I particularly worry when the cold engine is called upon for near max power in a passing or short interval merge situation.

At the same time, I have to think that is part of the design. Not much power and total computer control of the engine makes it possible to largely counter the effects of a short duty cycle. I think oil dilution is a red herring. With computer control and fuel injection; this isn't my old Oldsmobile.

Bottom line is that I'm going to, like with the battery, trust KIA's design. The designers don't know how long a trip I might take or when I'll have a mountain to climb but they sure know I'm going to need sudden bursts of a cold ICE occasionally.
 
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