HV Charge MPG experiment and results

[Danks]

Did an experiment on Sunday on a trip. Ran 41 EV miles to bring EV to 0 and then turned on HV charge. Charged as much as it allows. 68.5 miles in HV Charge mode @ 65-70 mph. Added back to 20.4 EV range. So gained about 0.3 miles EV per mile driven in HV charge. Ran some EV miles and some more HV charge. In all ran 108.2 HV charge miles on the way there. FIlled with 3.022 gal.

Drove HV on the way back home. Turned out to be 108.7 coming home. (We didn't start the trip from home so that explains the miles difference on the trip halves.) Filled with 2.912 gal.

So HV Charge was 87.8 miles / 3.022 gal = 29.05 mpg - BUT - that added 20.4 miles range. If I add those miles in it is 108.2 miles / 3.022 gal = 35.80 mpg.

HV was 108.7 / 2.912 = 37.33 mpg.

So not a lot of difference. Very little elevation change in West and Mid Michigan - 100 ft difference between start and mom's house. Light tailwind of 5 mph on the way home.

FWIW - When we switched to HV Charge I expected the tenths of miles of EV range to start climbing. They didn't. We drove for a while with the EV range showing a steady 0 until it had added enough to add a bar the the EV range indicator at which point the EV range jumped from 0 to 1.9. After that the tenths started incrementing.

 

[MrFixit]

Interesting test. Although not explicit, I assume you began with a full tank of gas.
I have not used HV Charge, but It is surprising that there is only a 4% penalty to do so.

Some will probably argue that your test was done entirely on flat terrain, and there may be a greater penalty under more severe conditions, blah, blah...
But your test is good because it maintained as many things the same as possible. That is the best way to get a truly fair comparison.

I am curious... When running in HV mode, the vehicle alternates between the battery and the ICE. When you operate for an extended period in HV Charge, does the ICE run 100% of the time? Also, with the flat conditions, was the ICE running low to medium RPM's (not the high RPM's referred to as Angry Bees)?

 

[Sandroad]

That’s some very interesting information, in particular the adding of 0.3 miles EV for every mile of HV charge mode. And yes, that part of Michigan is flat! However, I don’t think the gas usage comparison is reliable data. Just the difference in the auto shut off between the 2 pumps you used could account for some of what you found.

 

[Philemon]

So, depleting the battery and charging up to about 55% and doing that over and over is cheaper than just running in HV mode? Sorry to oversimplify something... Thanks


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[Danks]

Interesting test. Although not explicit, I assume you began with a full tank of gas.
I have not used HV Charge, but It is surprising that there is only a 4% penalty to do so.

Some will probably argue that your test was done entirely on flat terrain, and there may be a greater penalty under more severe conditions, blah, blah...
But your test is good because it maintained as many things the same as possible. That is the best way to get a truly fair comparison.

I am curious... When running in HV mode, the vehicle alternates between the battery and the ICE. When you operate for an extended period in HV Charge, does the ICE run 100% of the time? Also, with the flat conditions, was the ICE running low to medium RPM's (not the high RPM's referred to as Angry Bees)?

Yes. Full tank of gas for both halves of the trip. No. The ICE did not run 100% of the time. I did notice it not running at least on some of the few downhill stretches we had. I don't remember it not running otherwise. According to the energy flow, the ICE did not charge the battery 100% of the time when it was running (as I remember it). The power draw indicator on the dash was essentially the same for HV and HV Charge. The RPM were low to medium - really no noticeable difference between HV and HV Charge.

Regarding the penalty. The mechanical difference is 37.33 to 29.05 mpg a 22% penalty. What I would consider the effective difference - since HV Charge does add miles back to the range - is a 4% difference.

Another couple of things worth noting. No gear mode in HV Charge. Hardly any temperature difference between the two trips ~ 33 F. Also was running in Econ mode both ways.

 

[Danks]

That’s some very interesting information, in particular the adding of 0.3 miles EV for every mile of HV charge mode. And yes, that part of Michigan is flat! However, I don’t think the gas usage comparison is reliable data. Just the difference in the auto shut off between the 2 pumps you used could account for some of what you found.

I agree with you. A longer trip using more gas would reduce some of the effect of that variation. If I come up with a longer trip I'm game to try the test again.

 

[Danks]

So, depleting the battery and charging up to about 55% and doing that over and over is cheaper than just running in HV mode? Sorry to oversimplify something... Thanks


Envoyé de mon iPad en utilisant Inside EVs

Actually no. It cost about 4% more doing it that way as calculated by the 100 mile trip I did

 

[Geor99]

So, depleting the battery and charging up to about 55% and doing that over and over is cheaper than just running in HV mode? Sorry to oversimplify something... Thanks


Envoyé de mon iPad en utilisant Inside EVs

No, I think he is stating the exact opposite.

 

[Fast Eddie B]

I think basic physics states there must be energy lost if you’re doing extra and unnecessary discharge/charge cycles. If not, we’d be in the realm of perpetual motion.

What’s significant is how little is lost by invoking HV CHARGE. Still, for economy it’s best avoided.

 

[Mike95465]

I’ve done this experiment a few weeks ago while different results. In my experiment, I seen that I could eek out an extra 5-10 MPG when using HV charge, as calculated by the infotainment system.

I think that I can attribute this gain by pushing the motor into a higher brake specific fuel consumption efficiency rather than finding the elusive perpetual motion machine. If the motor is required to run anyway due to low battery and only a minimal amount of load is required, adding a moderate generator load to the equation could be more efficient.

I have about a 80 mile commute.
Starting with ~10% SOC as indicated by the HondaLink app.
I started HV charge as soon as I left the garage.
I was able to reach HV charge max after 35 miles, right before I arrive to work.
On my way home from work I used EV until depletion then switched to HV the rest of the way. My home trip uses a bit more miles since I have to pick up my kids so the added 10 miles is for that.

I alternated between this and just straight HV mode for 5 days and consistently beat HV mode with HV charge.

Michigan climate but no rain during experiment
Pretty steady route averaging 55 mph the entire time without much traffic or stopping.
No HVAC used during experiment
Seat heaters were used

I guess I’ll try to replicate the experiment next week and document the results. I know the infotainment system might not be the most accurate but it should be close. Close enough where I don’t have to stop to top off each day.

It would be awesome to review this engine’s BSFC maps someday.



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[Landshark]

Some day in the future, probably yesterday, ICE vehicles entering urban areas will be hit with a fee. With the Clarity PHEV, it will be possible to complete a long trip using petrol and recharge the batteries, if necessary, prior to entering the revenue generating area.

A note regarding the trip computer mpg calculation. On 2 recent 700 mile trips I’ve found the computer displays ~4mpg more than actual mileage calculated by using miles and gallons, the old fashioned way. This was consistent for 6-7 fuel stops.
Average displayed ~40
Actual ~36

 

[MrFixit]

Starting with ~10% SOC as indicated by the HondaLink app.
I started HV charge as soon as I left the garage.
I was able to reach HV charge max after 35 miles, right before I arrive to work.

Hum,
This is quite different than @Danks who observed the addition of 0.3 miles EV per mile driven in HV charge.

I think you are saying that you went from 10% EV to 60% EV (max HV charge) in 35 miles...
This would be more like 0.67 EV miles per mile driven in HV Charge (assuming 100% charge is 47 miles). More than double??

@Danks did state he was driving 65-70 MPH while you were more like 55.
Could it be your contention that HV Charge is actually better than HV applies at the lower driving speed and mostly diminishes at 65+ MPH?

If you do run a future experiment, may I suggest that you measure the actual gas consumed and odometer miles rather than using the vehicle reported MPG? There are many here who do not believe the reported values. Yes, an error in the vehicle numbers could be a wash between the two cases, but actual miles and actual gas would be more convincing.

 

[Mike95465]

A note regarding the trip computer mpg calculation. On 2 recent 700 mile trips I’ve found the computer displays ~4mpg more than actual mileage calculated by using miles and gallons, the old fashioned way. This was consistent for 6-7 fuel stops.
Average displayed ~40
Actual ~36

I agree that it is most likely not as accurate as the old fashioned method, however, is the calculation it uses affect the results of both test runs equally allowing for a comparatively answer more than a quantifiable one?

It’s cold out and I don’t like getting gas when it’s cold. [emoji3063]One of the reasons I got this car is to reduce my gas station stops.



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[The Gadgeteer]

Was the initial 41 house current EV miles part of the 108 miles? If it was then the “gas” mileage on that leg will be very inflated.

I have not kept careful accounting but on long highway trips I seem to get low to mid 40’s on HV mode (Not HV charge mode) which decreases if I do activate HV Charge mode.

I have often wondered about the relationship of EV gain vs. MPG drop of HV Charge mode.

 

[insightman]

Some day in the future, probably yesterday, ICE vehicles entering urban areas will be hit with a fee. With the Clarity PHEV, it will be possible to complete a long trip using petrol and recharge the batteries, if necessary, prior to entering the revenue generating area.

Why would the revenue-generating entity believe a PHEV driver would not activate their ICE within restricted urban areas? Would the criterion simply be that the vehicle could roll past the check-station with the ICE off, regardless of available EV range? It would seem that PHEVs would have to be equipped with some kind of state-controlled ICE lock-out device to put them on a par with BEVs.

 

[Landshark]

I agree that it is most likely not as accurate as the old fashioned method, however, is the calculation it uses affect the results of both test runs equally allowing for a comparatively answer more than a quantifiable one?

I don’t really understand the question as worded, but I believe I get it.

I’ll put forward this theory. If the trip computer is off by 10% after a 200 mile drive in HV, it could be off by a greater percentage after a drive of only 35 miles, in either HV or HV+. It’s just a theory.

As mentioned previously, running a gas engine to generate electricity to charge batteries and then using that stored energy to provide electricity to power motors to propel a vehicle is a multilevel display of inefficiencies. It is not unlike my solar/battery backup at the house. It works but it isn’t terribly efficient.

If it were the most efficient method to operate the vehicle then the default HV function should be start with EV full then run EV to zero range, HV+ to 60% charge, EV to zero, HV+ to 60%, etc...

 

[Landshark]

Why would the revenue-generating entity believe a PHEV driver would not activate their ICE within restricted urban areas? Would the criterion simply be that the vehicle could roll past the check-station with the ICE off, regardless of available EV range? It would seem that PHEVs would have to be equipped with some kind of state-controlled ICE lock-out device to put them on a par with BEVs.

I have no idea other than the fact that these vehicles are rolling tracking devices, so it wouldn’t be too difficult to detect the means of propulsion at any given moment.

It was something I read in a Clarity review and if I recall correctly, the article said the practice was being utilized in some European cities.

 

[ClarityBill]

I did notice it not running at least on some of the few downhill stretches we had. I don't remember it not running otherwise.

I don't think the ICE shuts off in HV Charge mode. Even at stop lights, it just goes down to 1200 rpm. (From OBDII)

HV mode has the ICE turning off when the battery charge is high enough, or the drive load is low enough (going down hills).

 

[Danks]

Was the initial 41 house current EV miles part of the 108 miles? If it was then the “gas” mileage on that leg will be very inflated.

I have not kept careful accounting but on long highway trips I seem to get low to mid 40’s on HV mode (Not HV charge mode) which decreases if I do activate HV Charge mode.

I have often wondered about the relationship of EV gain vs. MPG drop of HV Charge mode.

No. The initial - work, not house, current EV miles were not part of the 108. It is HV Charge miles vs HV miles with no EV mixed in.

FWIW - In the warmer weather we got 44-45 mpg on HV. This is our first HV trip running heater - which we ran the same both directions.

 

[Danks]

I don't think the ICE shuts off in HV Charge mode. Even at stop lights, it just goes down to 1200 rpm. (From OBDII)

HV mode has the ICE turning off when the battery charge is high enough, or the drive load is low enough (going down hills).

It turned off on ours in HV Charge going down a hill. It used regen to charge the battery during that little stretch. I remember being surprised to hear the ICE shut off when I knew we hadn't gotten any where near max HV Charge level and looked over to the energy flow to see what was going on.