Stealth Mode at Highway Speeds?

When the engine isn't consuming any fuel, but it is still spinning and you are traveling faster than the "stealth" maximum, it is referred to as "warp stealth".

For true "stealth", the engine must be motionless (zero RPM) and the system in HV mode.

 

Electric-only mode has an upper speed limit, so that something doesn't overrev. Somewhere between 70 and 80 kmh, in my experience. A ScanGauge will give better feedback as to when the engine is off than the dash mpg indicator.

The dash will sometimes shows up to the top mpg, which at lower speeds likely does mean the engine's off. But at highway speeds, say on a good downgrade, while the dash may indicate 99 mpg, the scangauge will show it's idling, typically around 900. Still getting very good mileage.

Just my 2 cents, I would take EV mode as it comes, maybe chase it a bit at lower speeds, but back off when the charge starts dropping. At that point pulse-and-glide is almost as efficient, and easier on the pack.

 

To simulate what is happening when in CC and going down a hill simply apply just enlighten throttle to keep the HSI energy bar in the first 1/4 of the display like this:



This is the same display you want to see when doing a true glide or warp stealth.

The key to great FE on the highway is learning to Drive with Load or maintain your speed going uphill but warp stealth on the downhill.

Want to know more about Driving with Load (DWL)? - CleanMPG Forums

 

The take home message is stop look at the arrows. They are useless on the GenIII.

 

Buy a Scangauge. That's all you need. When mpg hits 9999 you know the engine is not comsuming fuel.

 

^ You can also set one of the gages to RPM. Kinda frustrating Prius doesn't have a tach.

 

Aye. 0 RPM for engine off and 992 RPM for warp stealth.

 

3 would be needed... there's an engine, a small motor/generator, and a large motor/generator... each with the their own RPM values. The latter 2 can run backward (negative values) too. So, it's not as simple as one would expect. Knowing the coolant temperature in numeric format is very informative data too.

Fortunately, it's only $25 to add yourself. Get a Bluetooth adaptor to display the values on your smart-phone.

Be thankful we now (starting in 2012) have an indicator showing when the engine is off. Previous models didn't.

 

In Warp Stealth Mode is limited to about 46 mph, above that speed at 60 mph and the ICE willautomatically goes on - at a minimum of 992 RPM which is burning about .30-.50 gallons per hour.

However, the situation you are referring to is a very special situation when the High Voltage(HV) battery State of Charge (SoC) is greater than 73% - this translates to having all 7 bars light up on the Hybrid system indicator(HSI) SoC display. When this happens there is a risk that the HV battery could be damaged by overcharging. To extend the lifespan and performance of the HV battery - the onboard computer works to keep the HV battery SoC between 50% to 70%. Some where when the HV SoC goes over 70% to 75% the Prius onboard computer will temporarily turns off cruise control(CC) and turns off the gasoline engine(ICE) to prevent it from over charging the HV battery. If you have CC on - the dashboard CC indicator light will still be on but the CC has been internally and temporarily dis-engaged - to test this out if you can turn off the CC at this point - you will find that you not be able to turn the CC back on as long as the SoC is over 75% (I encourage you to test this out) - never fear your CC is not broken but just temporarily electronically disabled. To lower the HV battery SoC back to a safer level, the Prius onboard computer will only allow the electric motors to run UNTIL the HV battery SoC drops below 70% at which point CC is then restored and the ICE is re-enabled. I became acquainted with this undocumented *feature* on one of my +600 mile road trips when my ScangaugeII Xgauge SoC =78% and the Prius was going 70 mph in all electric mode along a downhill stretch of road. When your Prius SoC >73% and the Prius is in this all electric mode, the electric motors will whine very loudly (and at-least to me it sounded like a *Star Trek* Warp engine right before it goes super critical and explodes).

The driver can manually avoid recharging the HV battery by putting the transmission into neutral or B mode when braking.

hope this helps

Walter lee

 

I've noticed once in a while, and it could be my eyes are deceiving me, the car will stay in electric-only propulsion even though my gas pedal pressure is enough to push the HSI display bar a bit beyond the mid-way mark. I think this occurs when the state of charge is near or at full. Maybe another tactic the car has to limit charge?