Corolla 2.0 engine behavior with full battery

[Andinhovsen]

There's one thing I noticed while driving and didn't find an answer in the manual or anywhere on the internet. 

When I'm doing a very long downhill with no need to accelerate, just mild braking, the car shows the green EV sign and zero rpm, as we all know. But when the Battery becomes full, the EV sign turns off after a while, and the engine goes into ~1500 rpm. As long as I can rely on the computer, the fuel consumption remains zero. So my question is, what's the engine doing? Does the electromotor spin the ICU to discharge some of the Battery to prevent overcharging or something? If I use some of the energy, the car returns to its normal behaviour.

I'm just curious about how it works.

[Derek.w]

I suspect engine is turning on to power the aircon.

If Battery is fully charged then your electric motor can drive the car but this is depending on your car speed and other power factors.

Use B mode to slow your decent then brakes.

[forkingabout]

22 minutes ago, Derek.w said:

I suspect engine is turning on to power the aircon.

If battery is fully charged then your electric motor can drive the car but this is depending on your car speed and other power factors.

Use B mode to slow your decent then brakes.

No B mode on the 2 litre hybrid.

Just S with option of 1 - 6

[TonyHSD]

1 hour ago, Andinhovsen said:

There's one thing I noticed while driving and didn't find an answer in the manual or anywhere on the internet. 

When I'm doing a very long downhill with no need to accelerate, just mild braking, the car shows the green EV sign and zero rpm, as we all know. But when the battery becomes full, the EV sign turns off after a while, and the engine goes into ~1500 rpm. As long as I can rely on the computer, the fuel consumption remains zero. So my question is, what's the engine doing? Does the electromotor spin the ICU to discharge some of the battery to prevent overcharging or something? If I use some of the energy, the car returns to its normal behaviour.

I'm just curious about how it works.

Hi. 
you have your answer and you have understood the system correctly 👍 Engine is spinning by the motor generator to waste some energy to reduce Battery level to more appropriate level max  80% 

If you use B mode or pedal shifting on 2.0 this actually accelerates the whole process. 

[2badmice]

8 hours ago, TonyHSD said:

Hi. 
you have your answer and you have understood the system correctly 👍 Engine is spinning by the motor generator to waste some energy to reduce battery level to more appropriate level max  80% 

If you use B mode or pedal shifting on 2.0 this actually accelerates the whole process. 

As mentioned above, there is no B mode on the 2.0, we have park, neutral, drive, reverse and sport

[Cyker]

Your instincts are right - When the Battery is full you loose regen braking, so the car 'simulates' engine-braking as you'd use in a normal non-hybrid car by sending all that excess energy to the engine, making it spin and letting all the parasitic losses slow the car down.

 

[Gray86]

You can help slow the Battery getting to full by using engine braking by pulling the steering wheel paddles to simulate gears. I find using D2/3 downhill provides some engine braking and reduces amount of regen. If you wait for Battery to get full on hilly regions you risk overheating your brakes (which are quite small on the Corolla).