How does transition to Hybrid work when EV Battery runs out on highway

It will run in EV until the EV range is depleted. It will start the hybrid mode and start warming up the engine whether it is needed to move the car or not until it is completely warmed up. Then it will come on and off as the car needs it the move the car or charge the hybrid portion of the battery.

#1 in Easley,SC

 

some of us like to warm up the engine before putting a heavy load on it. toyota has taken measures to do that automatically when you run out of ev, but at certain speeds and loads (such as hill climbing) and ambient temps, the engine will be required to submit some power along with whatever hv battery is available, and i contend that that could be detrimental to the engine life. but i could be wrong.

 

Warming up the engine is not a problem. There is enough battery capacity to throughly warm up the engine to efficient operation. I have looked.

Bob Wilson

 

Sorry, Bob I'm not following this. Are you saying the traction battery is involved while the ICE warms up? Even if it is showing as fully depleted (realizing it's not truly depleted at the 'must-switch-over-point)?

I know with my Prime there is a noticeable dip in power at the zero-ev-miles-remaining/ICE cut in point, particularly on the highway. So I assumed there was no battery contribution at that point.

And I, too, try and get the ICE warmed up on a low-load stretch of road if I know I'm not going to make it home on EV, as my approach to home involves big hills.

Posted via the PriusChat mobile app.

 

The traction battery is used to start the engine and provide assistance, especially as the engine heats up. Just like the Prius.
The engine is just to assist the electric motors & charge the traction battery. It is not designed to normally propel the car solo except in "limp home" mode.

 

No, the engine (uses gasoline) can -fully- propel the car and is much more powerful than the motors (electric). Maybe not on a Volt, but on a Prius for sure! Just because it's a plug-in doesn't change the fact it's a hybrid, and in hybrid mode it's the same as the Prius hatchback powerwise.

 

The car automatically turns the engine on with plenty of time to spare.

 

I still don't understand the answer to the OP's question. Should there be a concern (especially up north). That a cold soaked engine will be going from a sitting (off) position to a situation that requires it to suddenly power the car at says 60mph without even a few seconds warm up?

 

What happens is during the engine warm-up, a minute or so, the engine runs at a low power setting but the bulk of the power comes from the traction battery. Although there are no metrics, use the power-flow display and you'll see what I mean.

Bob Wilson

 

Thanks for the clarification!

 

Not a concern at all. It will start in time to drive the car.

 

If the temperature gets to 14 degrees or lower, the engine will warmup no matter what mode you are in. Apparently by engineering design, Toyota must not see it as a criticial issue for the engine to cold start after EV depletion. Just a thought.

#1 in Easley,SC

 

Just to add to the above comments, Toyota has 20 years of real world experience designing Hybrids. I am sure they looks closely at any failures, especially for the first 150,000 miles or so,

 

I believe a regular Prius behaves similarly at cold-start: the engine starts up, but doesn't get a lot of load, just runs at a fast idle, while the hybrid battery supplies electrons to the transaxle, for the first block or two.

 

Some of the confusion might stem from the fact that some may assume that the EV battery is somehow a different unit from the hybrid battery. There is only one 8.8 kWh battery. In EV mode, Toyota allows the battery to drain about ~6.4 kWh before it switches over to hybrid mode. There is still ~2.4 kWh of electricity left in the battery when this switch-over happens.

As the engine warms up, just as in the "standard" Prius hybrid, the electric motor "helps" keep the car going before the gas engine can start being the main driving force.

 

I think we are over thinking this. The regular Prius we all know starts up a few seconds after you hit the start button so it has time to warm up, at least a few seconds or a minute before your going 60mph. When the Prius Prime starts up cold for the first time it could be going 60mph on the highway. So cold the concern is does it harm the ICE. From what people here seem to be saying is no. The ICE is designed to start a little bit before It has to get up to speed. Right?

 

No, it's not like the GEN III that starts and runs until it hits 164° no matter what. The Prime ICE starts but the battery helps it pull some of the load until it warms up even though the EV range is shown as exhausted. The energy monitor shows this is happening.

 

The warmup-on-the-freeway is one factor that turns me off plug-ins. We have the blockheater, and use it virtually without fail before first cold-start of the day, for a couple of hours. It's like starting the day with a hot bath.

 

There is nothing stopping you from putting a block heater in a Prime, if they would ever sell them in your province.