MPG "The Perfect Method"

I think he is trying to say that it is not monotonically increasing or decreasing. Which we knew. I think there is a confusion between overall drop in elevation (which obviously provides energy, and thus improves mileage) with local changes in elevation.

 

It should save your EV range once you switch to HV. However, if you switch from EV to HV, at say, 0.1 EV miles left, the car will end up consuming whats left of your EV range during the warm up. However, once the ICE is warmed up, it will take any opportunity it can to replenish the EV range you had when you made the switch.

Another idea you may be interested in is what Paradox here has appropriately named "Stacking" (I think he was the first to point this out). First you have to understand that if you've switched to HV and the car is "saving" your remaining EV range, when you regen, that EV range will still go up in either mode. If you leave it in HV, it will use up what you regen'ed (but will still save what EV range you had before you made the initial switch to HV). However, if you switch to EV, then back to HV, you'd be able to "re-set" your "saved" EV range. So it would work something like this:

1. Switch from EV to HV at 0.1 EV miles remaining
2. Car warms up, you're cruising in HV with 0.1 EV miles of range showing
3. Car coming to a stop, regenerating and adding EV miles
4. Car is now showing 0.5 EV miles once you've come to a stop
5. Hit the EV/HV switch to toggle back into EV mode
6. Hit it again to switch back to HV
7. Now you will have 0.5 EV miles "saved"
8. Repeat the process at the next stop

If I'm in traffic and about to run out of EV range, thats when I'll try to play this Stacking game. I've maybe gotten it up to 3 miles of EV that way. I think Paradox said he's been able to regen all his EV miles this way in traffic.

 

Damn. That is pretty cool. That could make the PIP useful for freeway drivers like myself who still have to navigate a few city miles here and there. I estimate even though my commute is 98% freeway I could get 80+mpg in a PIP just using the EV range on the city streets near my house or taking a back road here and there. Maybe I should have got a PIP instead. With my mad driving skills I'd be more stacked the Dolly err. Nevermind.

 

What is the point of "stacking"? Yes, your EV charge is going up, but you are "buying" it from the ICE when you go up the hills. Is it observed that it is more efficient to run the ICE on the uphill and bank the energy for use on the flats, than it is to just use the ICE on the flats in HV mode?

 

Did I see Brake Specific Fuel Consumption mentioned in the Plugin section. Hah, kinda ironic.

 

No, you're basically storing the energy you regenerated while going downhill or coming to a stop and utilizing that energy when you feel it would be more beneficial.

 

From about 2007 Toyota Japan had "i-Navi" as an option on its cars, being a navigation system that is aware of elevation. The idea being that it could advise the cruise control and try to maintain a near constant speed up- and downhill. This was for any car, not specifically hybrid. Sadly, my mother-in-law's Corolla (with CVT when the Australian Corolla had 4-speed auto) I was driving had standard navi. All it could do was warn me of traffic ahead and say in a cute voice just before an on-ramp, "BING! Careful now. Cars may be entering from the left-hand side."

The closest I can find in the Prius Alpha (Prius v) audio-visual catalogue is ESPO (Eco Passport) that records ECO Drive score, records it in your G-BOOK account and provides advice on your driving. The better your ECO Drive score, the more money is donated to ECO Action (which is a bit backwards, but anyway...) In the Prius PHV G-BOOK has some extra features relating to battery status, charging stations, etc.. That's not quite the same as an elevation-aware navigation, but interesting.

Is the PIP HV battery a single unit that can be charged by mains and by driving? Or is it segmented into a standard HV pile and a storage pile that can only charged by mains? I'm guessing that there would be different strategies for max mpg depending on whether you had a (1) 5.0kWh HV or a (2) 1.5kWh HV with 3.5kWh add-on?

 

It's a single unit with 4.4kWh total capacity, ~2.8kWh usable capacity.

 

Why is that ironic? If you are talking about the engine efficiency of a plug in BSFC is a critical measure to understand when the engine should be used. Even if itsused infrequently like the volt, we still talk about it .

BSFC would be pointless for a BEV.. but even there they have motor efficiency maps but they are different form.

 

4,500 feet of altitude is about 5.5 kWh, or 1/6 of a gallon of gas.

 

dolly madison?

 

Unless it looks like this, you're not actually in HV mode:


This is EV-BOOST mode, which depletes even though the engine is running:

 

you would trade the performance of a 25% efficient ICE over a 90% efficient electric motor? (that is 90% mostly due to conversion losses from the wall)

 

john, can you give us more details please? what are we looking at on the screens and what differences are we seeing? thanks!

 

The top screen with the line in the middle and the ECO icon and the battery with the stripes is the standard Hybrid display, like you would see on a non-plugin. The empty car outline signifies that the ICE is on. If the ICE is off, the empty outline is filled with "EV".

On the bottom, you are in an EV mode, but the the ICE is running for some reason (like needing heat, or going over 62mph), as indicated by the empty car outline. You are getting power primarily from the battery, and the battery is being depleted. Normally in EV mode, the battery icon is solid up the the level of charge, but when you have less than a mile of EV left, it shifts to the HV style. Also note that in the bottom display, the car icon is where the "ECO" icon was in the hybrid display, and it is bigger than in the HV display.

Just at a glance, the bar in the middle is the simplest way to know you are in HV mode.

 

There are 2 different modes available while driving faster than 62 mph (100 km/h).

Regular HV is when you explicitly push the button to halt EV depletion. This causes the Prius to revert to the usual 50 MPG hybrid driving.

If you don't push the button, the default EV mode transforms to EV-BOOST mode. This causes the system to take advantage of the plug-supplied electricity, which results in efficiency above 100 MPG.

When the EV symbol is small and the Eco-Meter has a center-divider to indicator a white zone, that's HV mode. It will remain that way until push the button again or shut the power off.

When the EV symbol is large and the Eco-Meter only has a green zone, that's EV-BOOST mode while driving fast. It automatically turns into EV mode when you leave the highway and changes back to EV-BOOST when you exceed 62 mph... or you accleration hard... or the heater cycles back on.