Not Using EV mode !

[UX250h]

Driving down to Southampton, the UX was not going into ev mode!  Even when braking, the engine would stay at 1000rpm, as a result, the hybrid Battery is 90% full.

I have just restarted it for the 3rd time and it now appears to be working ok....

Any ideas?

[Zotto]

High speed?

[NemesisUK]

Sport mode?

[UX250h]

No, this was at all speeds, I'm wondering if the aux Battery is low so it's charging that?

 

[Herbie]

7 minutes ago, UX250h said:

No, this was at all speeds, I'm wondering if the aux battery is low so it's charging that?

That won't be it. The hybrids don't have an alternator and the 12V Battery is charged by the traction Battery via a DC/DC converter, which also feeds the 12V systems such as lights, radio, wipers etc., etc., and it's very rare to have a faulty converter. Read the OBD codes to see if ther's any clue there.

[UX250h]

I'm thinking, if the 12V aux Battery is low, the engine will remain running to charge it. 

Btw...I've now driven for another hour and it seems fine (has the 12v Battery now charged?)

 

Never ever seen this before

 

[NemesisUK]

12 minutes ago, UX250h said:

I'm thinking, if the 12V aux battery is low, the engine will remain running to charge it. 

Btw...I've now driven for another hour and it seems fine (has the 12v battery now charged?)

 

Never ever seen this before

 

As Herbie says the 12v Battery is recharged via the traction Battery. It doesn't require the engine to run to do this.

I'd suggest it was simply a combination of speed, acceleration and engine load and traction Battery charge level.

[Herbie]

7 minutes ago, UX250h said:

I'm thinking, if the 12V aux battery is low, the engine will remain running to charge it. 

Btw...I've now driven for another hour and it seems fine (has the 12v battery now charged?)

The way hybrids work is that the 12V Battery boots the computers, pressurises the brakes and gets the car into READY mode. At that point the hybrid system is fully functional (charging the 12V Battery and running 12V systems) and you could drive away in EV mode alone, but you'd only get a mile or so, if that, before the hybrid system needs the petrol engine to run. Like a conventional car, the 12V Battery is only for starting and once the car has started, the alternator (or for hybrids, the DC/DC converter) takes over control of the 12V systems.

When the petrol engine is needed the hybrid system energises MG1 (Motor/Generator 1) and uses it to spin it up the engine to 1,000 rpm before applying petrol and a spark to fire it.

Given that, I would think it's just an unusual set of circumstances that caused the behaviour you witnessed but nothing to worry about.

[UX250h]

Great explanation, never this happen before on 3 years, maybe just a unique set of circumstances as you say

 

[Spock66]

In the winter this will also happen so the engine runs to help heat the car.

[Gary H]

I've had the odd 'quirky' moment with mine, but it's usually in the winter months when I usually find it doesn’t like to stay in EV mode very much. It'll take a long time with the engine running before it'll switch and when it does, barely more than the lightest of throttle use will kick the engine back in. 

As we're now approaching warmer months, all is fine!