EV deactivated as battery low

[purplefleece]

Driving along today a message flashed up briefly saying “EV deactivated as Battery low”. Nothing abnormal was heard or apparent at the time. 

I have a 2018 Prius Hybrid. Drive mostly in Eco mode. 25,500 miles on clock. 

Recently there have been a couple of occasions when the engine (meaning the petrol side of things I guess) has been running fairly loudly for short periods (a minute) when there wasn’t any need. Electric Battery showed charge. For example, today when it was at a standstill and in park. And nothing like heating or radio or lights were on. I turned engine off and on again and it was normal again, ie silent.

E Battery generally goes up and down as we drive - very hilly round here so is between 2-9 blips on the gauge depending on how much downhill we’ve done!

Any thoughts? 

[Trewithy]

I also live in a hilly area and it is much better to to drive in normal mode.  Eco mode is only beneficial when driving in city conditions with a lot of starting and stopping.  Although when in normal mode you can put the climate control in eco to help with economy.  

[purplefleece]

Thanks for advice about hill driving.

I would still appreciate any advice people might have about this message and over-revving at times. 

[Harters]

12 hours ago, purplefleece said:

..... I would still appreciate any advice people might have about this message and over-revving at times. 

The only time I have seen the message "EV deactivated as Battery low" is when driving in EV using the EV button and the Hybrid Battery gets low or when pressing the EV button when the Hybrid Battery does not have enough charge, if that was your situation, then it is perfectly normal.  

When the ICE goes through a charge cycle when the Hybrid battery needs to be charged, the engine is often revving more than normal and it will go down in revs and then up in revs generally just before it is about to finish the charge cycle.

[purplefleece]

5 minutes ago, Harters said:

The only time I have seen the message "EV deactivated as battery low" is when driving in EV using the EV button and the Hybrid battery gets low or when pressing the EV button when the Hybrid battery does not have enough charge, if that was your situation, then it is perfectly normal.  

When the ICE goes through a charge cycle when the Hybrid battery needs to be charged, the engine is often revving more than normal and it will go down in revs and then up in revs generally just before it is about to finish the charge cycle.

Not sure I follow that. While my car does have an EV button, it doesn’t work as the car is a hybrid. On adjacent button, have choice between ECO, Normal and Turbo. 

[Harters]

1 hour ago, purplefleece said:

Not sure I follow that. While my car does have an EV button, it doesn’t work as the car is a hybrid. On adjacent button, have choice between ECO, Normal and Turbo. 

The button will work and drive the car is electric vehicle mode, but only at low speed and for a very short distance.
 

I only use it to enable me to take my car out of the garage for washing without having the ICE start up. 
 

BTW when you say Turbo, I guess you mean Sport?

[TonyHSD]

Good advice given and correct 👍

The only time the car will show ev mode not available and will point a reason is when manually selected via ev mode button. In any other cases and they can be numerous the car will do it’s things without displaying any messages. 
Toyota hybrids may rise engine rpm to very high 3k and above after a long downhill and when hybrid Battery is fully charged. In this situation if ev mode buttons is pressed the car will refuse to go in ev mode and the message displayed will be “ ev mode currently unavailable “. When Battery is low and you select ev mode the car will again refuse to go in ev mode but this time the message will be ev mode not available, Battery too low, and the third time when the car can refuse ev mode manually selected via the button is when the vehicle speed is too high, the message will be ev mode not available, excessive speed. 
In normal driving circumstances the car will not display any messages about driving modes. 
For eco or normal or power ( sport) the best one is Normal mode. 

[purplefleece]

6 hours ago, TonyHSD said:

Good advice given and correct 👍

The only time the car will show ev mode not available and will point a reason is when manually selected via ev mode button. In any other cases and they can be numerous the car will do it’s things without displaying any messages. 
Toyota hybrids may rise engine rpm to very high 3k and above after a long downhill and when hybrid battery is fully charged. In this situation if ev mode buttons is pressed the car will refuse to go in ev mode and the message displayed will be “ ev mode currently unavailable “. When battery is low and you select ev mode the car will again refuse to go in ev mode but this time the message will be ev mode not available, battery too low, and the third time when the car can refuse ev mode manually selected via the button is when the vehicle speed is too high, the message will be ev mode not available, excessive speed. 
In normal driving circumstances the car will not display any messages about driving modes. 
For eco or normal or power ( sport) the best one is Normal mode. 

It’s very helpful to hear about the role of that high periodic revving. And also explanations for EV mode. 
 

It sounds as if the brief message that flashed up on dashboard “EV deactivated as Battery low” was a random thing. 

[TonyHSD]

19 minutes ago, purplefleece said:

It’s very helpful to hear about the role of that high periodic revving. And also explanations for EV mode. 
 

It sounds as if the brief message that flashed up on dashboard “EV deactivated as battery low” was a random thing. 

This ev mode deactivated message can only show if ev mode was selected beforehand. Perhaps you may have pressed the ev button by mistake without realising that the car drives in ev mode until the Battery went low and the car had switched back to hybrid mode and displayed the message. I think this is what most likely had happened in your case.