Auto EV/HV vs HV

[jmk]

Maybe is this a common question : when should the "Auto EV/HV" mode be used, vs the "HV" mode ? In the end, I am still unclear why the toyota engineers have implemented the "auto EV/HV" mode, in addition to the "HV" mode. As for the "EV" mode, this one is obvious. Thank you !

[Yugguy1970]

I'm not sure what you mean by auto ev/hv? Or HV?

You can use EV button to make the car use Battery only, and then only under certain circumstances.

Other than that the car will swap between ice or ev or both or charging all under computer control.  You have a little bit of control by choosing eco, sport or normal but that's it. 

[philip42h]

20 minutes ago, Yugguy1970 said:

I'm not sure what you mean by auto ev/hv? Or HV?

You can use EV button to make the car use battery only, and then only under certain circumstances.

Other than that the car will swap between ice or ev or both or charging all under computer control.  You have a little bit of control by choosing eco, sport or normal but that's it. 

The OP is talking about a PHEV aka US Prime - not a humble HEV like ours ... 🙂

The PHEV owners will respond shortly!

[ernieb]

PHEV owner.  I nearly always leave the car in EV knowing it will switch automatically into HEV mode when the traction Battery has reduced to 30% and pure EV is no longer available to me.  I’ve done some trials when doing trips I know are beyond the EV range and found that after it’s initially run the ICE, I guess to warm it up, runs in EV mode until it’s used the traction Battery more or less as I would have done.  It only switches into HEV with the ICE on if I push the car up a hill or accelerate hard.  I’ve found little difference between me intervening and my normal practices or consuming the traction Battery then letting it switch itself.

[nlee]

EV keeps it in electric only mode. HEV mode keeps it acting like the normal HEV and doesn't use the Battery up. The suggested use of this is if you leave home, straight onto the motorway but want to save the Battery for EV mode at your destination. Auto mode prefers to use Battery but will call for the ICE to support if you accelerate hard or power up a hill.

[philip42h]

So, to answer the OP's question ... Auto EV/HV should probably be regarded as the 'default' normal mode of operation - it let's the car decide how best to balance the power options available to it/you. Use EV when you want to drive as an EV as far / as much as possible. Use HV when you want to save up the available Battery charge for use later in the journey.

I think ... 😉

[ernieb]

It’s interesting that the car defaults to EV mode. As I’ve said above I’ve tried numerous ways to see what comes out best in terms of economy and there’s not much to choose so by default I leave the car in the EV mode and let the HEV mode kick as required.  Even if you save the EV mode for a congestion zone there is no benefit other than a warm glow of satisfaction.

I think in the end it’s down to personal choice, it would be interesting to see what other PHEV owners do by default?

[nlee]

Normally I do the same as you Ernie, other than for longer journeys I'm likely to us the HV mode because it's only 2-3 miles to the dual carriageway/motorway so save the EV for going around town at the destination. I too was surprised the default was EV rather than auto.

[jmk]

Thanks for the various answers, which confirm my feeling : Auto EV/HV (only on PHEV indeed) seems to aim at optimizing the hybrid Battery consumption by triggering the ICE under stronger power sollicitations and reverting back to EV automatically when optimal conditions are met again (if the Battery is still charged enough). In the end, when starting a journey that I know in advance will be beyond the EV range, my feeling is that engaging Auto EV/HV "may be" more efficient than the default EV with automatic switch to HV when the Battery comes to low charge.

But this is not obvious, hence my initial question !

[Lawnmowerman]

Having had an HEV for almost 3 years, it takes some getting used to when it is in pure EV mode at speeds in excess of 60mph. They do say it can be in EV at top speed although I suspect the criteria might be quite rare to achieve this.

[ernieb]

The PHEV will do 85 mpg in pure EV mode and I regularly use the motorway at the legal limit without any problems. Certainly if you use hard acceleration and maximise the speed then the range on EV will be lower but this is the same as using the ICE the harder you hit it the more fuel it uses. I’ve achieved around the 45 miles range at speeds averaging 60+ mph mild temperatures with the AC on, I’m sure this would be lower as it gets colder.  I’ve also used pure EV for passing traffic without the ICE kicking and was still impressed with the acceleration not as good as the HEV mode but no problem in terms of confidence that the move was going to happen.

[Lawnmowerman]

9 hours ago, ernieb said:

The PHEV will do 85 mpg in pure EV mode and I regularly use the motorway at the legal limit without any problems. Certainly if you use hard acceleration and maximise the speed then the range on EV will be lower but this is the same as using the ICE the harder you hit it the more fuel it uses. I’ve achieved around the 45 miles range at speeds averaging 60+ mph mild temperatures with the AC on, I’m sure this would be lower as it gets colder.  I’ve also used pure EV for passing traffic without the ICE kicking and was still impressed with the acceleration not as good as the HEV mode but no problem in terms of confidence that the move was going to happen.

Oh yes, that EV motor set up has grunt in spades 🙂

[ernieb]

Example:

Competed a 114 mile trip today, early so lights on, windscreen wipers, heater/AC, outside temp 16oC so not too cold. I got 51 miles on the EV which took an hour of mixed driving and when the HEV mode kicked in averaged 504 mpg for the rest of the trip. I just used the EV for the first part of the trip and let HEV kick in when EV mode was depleted, my normal driving mode for this type of trip.  This is equivalent to an overall 91 mpg, which is the way the MyT app records the data.