Gasoline vs. Electric motor

Just let the cars computers do the thinking, they will protect the traction battery.

 

Are you attempting to force battery use? If that is the case, then just change the screen view and drive as if you don't know there is anything other than an IDE under the hood. See if that changes anything.

For what it's worth, though, I rarely move from the HSI screen, as it gives me very good and immediate feedback in terms of fuel economy and "stealth" driving. I never worry about whether the battery has six/seven bars or just two, as I know the computer is monitoring everything and will protect the HV battery.

 

At that low average speed, I don't think you have much choice. Once the ICE is warmed, the car is going to heavily favor electric mode, and the battery level will tend to hover near 2 bars.

As a_priori hinted, don't attempt to force electric mode, just drive naturally and let the car make its own choice. If you want to 'force' different operation, I'd suggest trying a traffic-matched Pulse & Glide, pushing the HSI bar to the right and turning on the ICE during the pulses, if you can make it fit traffic conditions and if you can achieve a better round trip MPG than just driving naturally. But if you can't find a pattern that works, or it if takes too much work and attention, or if the resulting MPG doesn't increase, or if the ICE pulses lead to increased braking (regenerative braking is still lossy), then go back to driving 'naturally'.

What MPG are you getting now? What is your approximate location? Outside temperature?

 

I think you may find the mileage will be very good traveling at 45 mph. There are times to use just the battery, but I think they are rather infrequent and occur only when you are trying to avoid having the ICE on for a very short time with no need to really increase speed. For the most part, the better fuel economy comes from getting up to speed and letting the terrain and traffic guide you -- gather more speed going downhill and bleed it off going uphill. Anticipate stoplight changes. Don't clog traffic.

I'd also lower the windows and soak in some of that sea aroma. It will lower your MPGs but increase your enjoyment.

 

Once the engine is warm, it should shut off naturally at stops and during glides, without you having to force it. Then, while you are stationary, the engine ought to stay off until the car decides the battery is too low and needs recharging, or the coolant gets too cool.

One of the goals of traffic-matched P&G is to do the battery recharging during the Pulse phase, so the engine doesn't need to fire up while you are stopped. However ...

You are already doing quite well. I don't know if there is much room for improvement without a ride-along from an expert such as Wayne Gerdes, who'll push for 86 mpg.

You should be using the ICE in the pulse or acceleration phase even below 45 mph, for both propulsion and for battery recharging. Save the electric for the lowest speeds, and to extend glides after reaching travel speed on the ICE. If you keep speeds below 45, then the ICE will quickly shut off when you back off on the gas pedal, for most efficient gliding.

At and above 45, the ICE must still spin even when it quits burning fuel, which makes for a bit less glide efficiency. And in Gen3, this spin can be a bit sticky -- as you slow down below 45, the transition from 992 RPM to 0 RPM can be significantly delayed while the car waits to make sure you aren't soon speeding back up. If you never get up to 45 mpg, this stickiness doesn't happen.

And keep watching the daily round trip MPG. I believe friendliest battery use should align fairly well with high MPG. If MPG falls, go back to your old style.

 

Its always better to avoid relying on the electric motor.

You can minimize your reliance on the electric motor
if you set the Prius throttle to Normal or Power mode.
and if you do mini-Pulse and Glides.
In a mini Pulse and Glide you are going at lower than normal speeds
for shorter time periods
Say you are on a very flat smooth road surface ....
You are at a dead stop at stop sign ,
Press the accelerator lightly never going pass 1/4 of the ECO bar
build up speed to 5mph to 10mph on electric
( this is to eliminate initial inertial forces),
then
(start mini- P&G cycle)
press the accelerator down very fast so
the HSI display is past the 1/2 "ECO" marker on the top
to start the ICE -- the HSI indicator should be slightly past the "C" of the "ECO" marker
until you reach your target max speed (e.g. 18 mph),
then let go of the accelerator so that the HSI indicator is
now on the far left side of the ECO bar
(and the gas engine automatically turns off and the electric motors are off or bearly running)
but regenerative braking is not occuring
Glide until the Prius speed drops down to your target low speed(e.g. 12 mph)
(repeat mini-P&G cycle)

you target max and low speed are based on the traffic you need to work with.

 

Looking at the HSI, press just enough to remove the regen drag, so that no power or regen is indicated. This is a glide.

 

You will not be in a glide unless you are pressing the accelerator pedal, ever so slightly. If you let off the accelerator, you will be coasting in a mode that Toyota designed to emulate an automatic transmission. The ICE doesn't cause drag, but the one electric motor will be dragging (I believe it works that way). By depressing the pedal, you can cause the other electric motor to counter the spin of the former and produce, effectively, a neutral drive position. This is the glide you seek, and you can see it, more or less, on the HSI screen. It is when there are no bars evident: none to the left (which would be regen) and none to the right (which would be power output).

This happens on a regular basis. So does six bars. Don't let it bother you, unless that is all you ever see. If it is, then you likely are relying too much on the electric drive, meaning you have to be using the ICE to generate power to be stored in the battery. This is an inefficiency you want to avoid more often than create.

 

It sounds like you are pretty far along on the learning curve already. Enjoy!

 

When only 2 bars are left on the HSI SoC gauge (about 40%-45%) the Prius will automatically restart the ICE and recharge the HV battery back up to 50% (usually four bars). If the Prius is standing still (at a stop) while it is automatically recharging the HV battery that trip's FE tends to drop about 5 to 8 MPG. The only time the Prius gas engine will not recharge the HV battery is when the Prius is out of gas - at which point the Prius will run on electric power only until the HV battery is fully drained - which is a very very very very bad thing. If the Prius HV battery is drained to zilch - the Prius will need to be towed to the dealership to recharge the HV battery before it can use gasoline again. The Toyota dealership will likely be the only place you can recharge the Prius HV battery. One cannot jump start the Prius via 12vdc aux battery with a dead HV battery because the 12 vdc aux battery does not power the starter motor. The HV battery powers the starter so when the HV battery is fully discharged - the Prius will be unable to start up regardless of whether it has gas or not. Draining the HV battery to zilch will also shorten the lifespan of the HV battery as well. At least that's how I understand the mechanicals.

 

If you are maintaining a constant speed on a level road, the HSI bar should not vanish as it does in a true glide. If it really vanishes, then either the road has some downslope, or car car is gradually slowing.

It is common in stop-and-crawl traffic, and is normal in such situations unless one makes a special effort to avoid it. On free flowing roads, it is rare unless one is forcing electric mode for some reason.

 

No not really. If you can go 45 mph, and trafic is fine with you at 35 mph, pulse and gliding between the two, or maybe up to 42 and down to 35 might use less gas, and actually save time. If you have juice in the battery accelerating to 10 mph on battery may make sense, but if your at 2 bars, go ahead and giver it a little gas. You are much more fortunate in route to get 65 mpg+. Let us know if you like the pulse/glide game and if i gets your mileage even higher.

On a glide you do want to press on the accelerator until the their is no charge or discharge on the hsi. That is close to neutral and the engine will turn off at your speed, but not waste momentum by charging the battery. I often get to 2 bars, but I have hills and air conditioning. Traffic jams in the heat always get my battery low. If your battery is at 2 bars you may want to just go at a constant speed until it is charged up, instead of gliding down.

 

If you are already averaging 64 mpg, you really don't need much help, you're doing 20 mpg better than I and I also live in Santa Monica.

 

After you do enough P&G cycles, it will become muscle memory/habit and you won't have to look at the HSI display nearly as much.

Assuming you have long enough sections on your commute, I think feathering in a tad more throttle to get the indicator about 1/5th way into the EV side of the display will greatly extend glides while not eating up too much battery. YMMV (literally)