Heading to Mammoth Mountain from the Bay Area

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I still wonder about 'resetting the HV' mode to reduce rpm's on climbs. I do it in NY, but my hills seem to be shorter, and farther apart.

By switching out of HV, and back into HV, the car will go back into gear mode, and keep the rpm's down. Each time you do this, it costs some EV range, so there is a limited amount of resetting available.

Has anyone else tried the reset?
 
ClarityBill said:
I still wonder about 'resetting the HV' mode to reduce rpm's on climbs. I do it in NY, but my hills seem to be shorter, and farther apart.

By switching out of HV, and back into HV, the car will go back into gear mode, and keep the rpm's down. Each time you do this, it costs some EV range, so there is a limited amount of resetting available.

Has anyone else tried the reset?
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Ideally you want to use the engine as the main source of power and the battery as backup for some assistance. Resetting HV might help to accomplish this. The closest driving mode is EV sport, but it relies mostly on battery, so you lose charge relatively quickly.

I don't think the car can climb in gear mode in our steep mountain roads.
 
My experience with gear mode, is it stays until you lose about 2 miles of EV range (most of my experience is at cold temperatures, so 2 miles of EV range is about 5% SOC)... I would be curious to see if it does not stay engaged on your steep mountain roads, until it has lost some EV range: Is there something else that causes it to go out of gear mode? (besides low speed)

Speeds below 45 mph will drop it out of gear mode, but resetting HV at lower speeds should also reduce the rpm's. If HV is not reset, the ICE will be working to maintain battery charge and provide power to the drive wheels, rather than using the battery to supplement the drive power.

The goal is to avoid high rpm's while using ICE and battery for power, not just battery, and not just ICE.

Just my opinion, based on the way I like to drive.
 
Agzand said:
If I was going to do this trip again, I would use EV sport for some of the climbs and I will also use HV charge mode to regain battery charge during easier and downhill sections of the road.
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As I've previously stated it would be nicer if the car's brain took a long term view of battery usage in HV rather than a short term view, kind of like what you are trying to do but with the engine on constantly. Our batteries are much larger than non PHEV hybrids so the car doesn't have to operate like them. The engine could then just run at a near constant but reasonable rpm (2000-3000) and let the EV range drop 10 or 15 miles on an uphill, then put it back in on the downhill. Of course as EV range was used it would gradually have to go into a shorter and shorter term view of the situation.

This would also help a situation I often find, in HV the car decides its caught up in replenishing the battery so it turns off the engine on a long slight downhill, then it starts climbing the next hill in gear mode but halfway up its back out of gear mode because the EV range has dropped 2 or 3 miles again because it didn't save enough charge.
 
David Towle said:
This would also help a situation I often find, in HV the car decides its caught up in replenishing the battery so it turns off the engine on a long slight downhill, then it starts climbing the next hill in gear mode but halfway up its back out of gear mode because the EV range has dropped 2 or 3 miles again because it didn't save enough charge.
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Wow. Great observations and insights by everyone. I’m learning a lot from you all.
One question. Isn’t the gear mode stopping due to torque and speed considerations and not because of EV range or SOC dropping. I thought it came out of gear mode because there is no gear ratio to change so the rather small Atkinson cycle engine has a narrow range of rpm, speed and torque that it can work in when in gear mode. And I have seen charge flowing into the battery while in gear mode.
So have I got this right or not?
I cheerfully defer to the Clarity Brain Trust on this.
 
KentuckyKen said:
Wow. Great observations and insights by everyone. I’m learning a lot from you all.
One question. Isn’t the gear mode stopping due to torque and speed considerations and not because of EV range or SOC dropping. I thought it came out of gear mode because there is no gear ratio to change so the rather small Atkinson cycle engine has a narrow range of rpm, speed and torque that it can work in when in gear mode. And I have seen charge flowing into the battery while in gear mode.
So have I got this right or not?
I cheerfully defer to the Clarity Brain Trust on this.
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No that's not correct. Here's what the system does, starting with a hypothetical steep downhill transitioning to a long steep uphill:
1. Regen going back to the battery to maintain speed, engine off.
2. Coast, no regen, engine off
3. Battery/motor propulsion, engine off
4. Engine turns on, once it gets its bearings goes into gear mode, excess engine power goes to generator and then battery
5. Engine output balanced with car needs, all engine power goes to gear drive propulsion
6. Battery/motor adds power to what gear mode provides. This could go on a long time if more battery depletion was allowed.
7. But after a mile or two the system decides the battery has depleted too much, stops gear mode, increases engine revs to generate more power for just electric propulsion.

Remember in EV mode the car could go up the hill fine on just electric, so obviously it can also go up the hill fine on electric plus gear drive. But the drop in SOC doesn't allow that to continue as long as I would like..
 
I forgot to say this is what happens in favorable weather. In the winter there were times I would see no gear mode operation at all, I assume that's because somehow the generator mode is usually more efficient than gear mode in cold weather. But I have no idea why that is.
 
I live in cold weather, and gear mode works in cold weather: But the heater draws down the battery faster, so it drops out of gear mode. Resetting the HV brings back gear mode, even in cold weather.

It seems like the heater runs, even when the ICE is operating: I still need to figure out how to get an amp meter on the Heater, to be sure when it is operating.
 
In gear mode the ICE produces about 1/4 of the power gauge at 65 mph. (3/16 at 60, and 7/16 at 70.)

The battery will add or subtract power to match the driving power requirement. If the battery is subtracting power (regen), and the SOC rises too much, the ICE will shut off. If the battery is adding power and the SOC drops too much, the ICE will end gear mode, and increase the rpm's to supply more power to try and keep SOC from falling. RPM's will rise gradually as the SOC drops: If SOC keeps dropping, rpm's will max out about 5500.

Switching out of HV and back into HV (HV reset), will start the process over, and the ICE will begin in gear mode rpm again.

As David Towle said, the problem with this is the system does not matter what the absolute value of the SOC. It just tracks the drop from the initial SOC. It only allows about 2 EV miles lost on battery before ending gear mode. It should allow drop to 5 EV miles remaining before ending gear mode.
 
KentuckyKen said:
One question. Isn’t the gear mode stopping due to torque and speed considerations and not because of EV range or SOC dropping. I thought it came out of gear mode because there is no gear ratio to change so the rather small Atkinson cycle engine has a narrow range of rpm, speed and torque that it can work in when in gear mode. And I have seen charge flowing into the battery while in gear mode.
So have I got this right or not?
Click to expand...
Not sure if we had clearly answered this question, so try this:

I am pretty sure gear mode does not stop due to torque and/or speed considerations. The speed has stayed the same. The torque is conditioned by the output from the battery. The ICE is just happily running at 'synchronous' speed, the charge flows in and out of the battery to make up the difference to the drive conditions: Until the battery SOC decides the ICE needs to do something different.
 
Thanks to all for sharing their observations and very cogent explanations.
“If I have seen further than most, it is because I have stood on the shoulders of giants”. I appreciate that the collective Clarity Brain Trust has so many giants as the above posts prove.

OTOH, since my Clarity gives me 48 mpg (after accounting for SOC loss) on my occasional long highway trips, I’m not going to obsess over how often it stays in gear mode. Especially since I’m already obsessing somewhat over EV range and winter cabin heat. (I may have to ask @insightman for his preferred brand of winter coat and gloves!)
So HV for me is so economical with no angry bees or power loss, that I’m happy to let the algorithm choose whatever it wants. (Although it’s nice to know about the HV reset idea if I ever need it.)
 
ClarityBill said:
I live in cold weather, and gear mode works in cold weather: But the heater draws down the battery faster, so it drops out of gear mode. Resetting the HV brings back gear mode, even in cold weather.

It seems like the heater runs, even when the ICE is operating: I still need to figure out how to get an amp meter on the Heater, to be sure when it is operating.
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I have gone as much as 100 miles on the highway in the winter with no gear mode. It probably is speed related, do you keep your speed down in the sixties?
 
I normally have ACC set at 74 (running 72-73 mph). In cold weather (below 20F), the battery does not receive charge very well, so have to run SOC below 30%.

Once the SOC drops below target, it has to come back up for gear mode: In cold weather and high SOC, the SOC does not recover very well. At lower SOC the battery receives charge better, and offers more flexibility in gear mode. Alternatively, the HV reset gives a new target that ICE can reach (since it is already there).

I am just starting to experience warm weather driving - gear mode seems to be less elusive. I am assuming KentuckyKen does not live in the frozen north, and has been enjoying gear mode in warmer weather. I have trouble getting 40 mpg when not driving in gear mode.
 
You're about same speed as me so I don't know why the difference. I never noticed a difference in the battery accepting charge as long as it was under 95%. The reluctance to use gear mode was worst with combined cold and precipitation, either rain in the thirties or snow below freezing.
 
Yes, that 48 mpg was on a ~500 mile round trip from Lexington KY to Johnson City TN in July (with AC on) and I accounted for loss of SOC so it’s an honest 48 mpg. The engine ran for ~2/3s of the trip according to the hour meter I installed. I saw every possible energy flow and the gear icon was not illuminated for the large majority of the trip, just for some of it. I also had no angry bees and plenty of power. As far as my wallet is concerned, the Honda engineers hit a home run with the power train algorithm.
 
KentuckyKen said:
Yes, that 48 mpg was on a ~500 mile round trip from Lexington KY to Johnson City TN in July (with AC on) and I accounted for loss of SOC so it’s an honest 48 mpg. The engine ran for ~2/3s of the trip according to the hour meter I installed. I saw every possible energy flow and the gear icon was not illuminated for the large majority of the trip, just for some of it. I also had no angry bees and plenty of power. As far as my wallet is concerned, the Honda engineers hit a home run with the power train algorithm.
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Interesting that your ICE only ran 2/3 of the time. Mine runs almost 100% of my highway time (70+ mph), with the heater running. I may have seen my ICE shut off with the warmer temperatures, but I need to have more warm weather drive time to see what it is doing - probably the same as yours.
 
David Towle said:
You're about same speed as me so I don't know why the difference. I never noticed a difference in the battery accepting charge as long as it was under 95%. The reluctance to use gear mode was worst with combined cold and precipitation, either rain in the thirties or snow below freezing.
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My statement that the battery does not accept charge well at higher SOC is partially guided by the fact that HV charge mode only takes it up to 57%: If the higher SOC did not affect recharge capability, why would they stop at 57%? My impression is cold weather makes this characteristic more pronounced.

I see more loss of EV range when switching to HV at higher SOC.

Precipitation also means the windshield wipers (and/or defroster) are adding to the electrical load: Dropping SOC.
 
ClarityBill said:
Interesting that your ICE only ran 2/3 of the time. Mine runs almost 100% of my highway time (70+ mph), with the heater running. I may have seen my ICE shut off with the warmer temperatures, but I need to have more warm weather drive time to see what it is doing - probably the same as yours.
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LOL. I’m just the opposite. I’ve never run HV in cold weather. So my results are probably skewed due to temps.
I did notice that any downhill at all, no matter how gradual or short, that put the car in regen caused the engine to shut off almost immediately. Thats ok, but the thing is that then it took a while after the engine restarts to get back in gear mode.

As others have mentioned, I wonder if the algorithm could be tweaked to achieve more gear mode and give even better mpg. In any event, I’m happy with the way mine works, just wondering if it could be even better. Too bad there’s no hackers guide to the Clarity so we could play around, try different settings, and then reflash it back to OEM when we inevitability brick the while thing.
 
ClarityBill said:
My statement that the battery does not accept charge well at higher SOC is partially guided by the fact that HV charge mode only takes it up to 57%: If the higher SOC did not affect recharge capability, why would they stop at 57%? My impression is cold weather makes this characteristic more pronounced.
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Then why does the Clarity allow regen braking to charge above 57%? My wild guess for the 57.7% HV CHARGE limit I is to leave room for regen charging on the other side of the mountain. That way there's less chance of regen fully charging the battery and activating the ICE as part of the Clarity PHEV's pseudo engine-braking scheme. (With me, it's always all about the pseudo engine-braking scheme.)
 
insightman said:
Then why does the Clarity allow regen braking to charge above 57%? My wild guess for the 57.7% HV CHARGE limit I is to leave room for regen charging on the other side of the mountain. That way there's less chance of regen fully charging the battery and activating the ICE as part of the Clarity PHEV's pseudo engine-braking scheme. (With me, it's always all about the pseudo engine-braking scheme.)
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I can understand HV charge to 80% to leave room for engine braking... (20% remaining - 6-10 EV miles): The remaining gap seems too big to be just keeping regen available.

Another thread on this forum has some graphs of battery discharge and recharge capacities that show more balanced operation at 50% SOC. They also show the dramatic affect of cold temperatures. My experience with gear mode would agree with balanced operation at mid-level charges, and cold weather impact on the battery.

Seems like you and I have different understandings of the operation of the Clarity.
 
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