PHEV: MPG with depleated battery?

[Roker]

Just a theory for discussion. 

Adding any extra weight to a hybrid like a spare wheel etc or taking in to account of the Battery weight, should not effect the mpg because all of the kinetic energy by accelerating or going up a hill in the weight is returned back to the Battery when slowing down or going back down a hill

[robo1]

Problem is regenerative breaking is only 60-70% efficient so energy is lost.

[nlee]

I drove back to North Wales from Gatwick yesterday. I'd used all the EV range on the way down. I topped up with fuel on the outskirts of Crawley which resets the fuel efficiency (that's the setting I use - Tank Average). 99% of the journey was on motorways doing between 50/75mph depending on traffic and roadworks. Two people and luggage, lights, wipers and A/C on. After completing the journey the MID indicates 52.8mpg. So that's basically using the PHEV as a HEV.

[philip42h]

1 hour ago, ernieb said:

Rightly or wrongly I've always assumed that the PHEV has the potential to recover more energy than the smaller capacity batteries in the HEV model?  Some hills I go down I generate 4 miles or more of regenerated energy.

While that is true, you have also used far more energy to get the PHEV up the hill in the first place. Up and down hills is the situation where the increased weight of the PHEV works against it.

[NASY]

Interesting stuff comparing PHEV with HEV. I previously had a Lexus HEV which always seemed to lack enough Battery reserve to gather all the potential on offer from regeneration. The PHEV certainly does appear to gather more regeneration however that trade off with extra weight may not be a sum gain -  still mightily impressive economy, 50 mpg no problem even on local runs.

[Cyker]

8 hours ago, Roker said:

Just a theory for discussion. 

Adding any extra weight to a hybrid like a spare wheel etc or taking in to account of the battery weight, should not effect the mpg because all of the kinetic energy by accelerating or going up a hill in the weight is returned back to the battery when slowing down or going back down a hill

This might be true in a theoretical model, but in the real world you'll always use more energy going up than you'll get back going down; Even EVs have this problem and they can regen much more energy than hybrids. (Potentially at least!)

 

 

[Flatcoat]

8 hours ago, Roker said:

Just a theory for discussion. 

Adding any extra weight to a hybrid like a spare wheel etc or taking in to account of the battery weight, should not effect the mpg because all of the kinetic energy by accelerating or going up a hill in the weight is returned back to the battery when slowing down or going back down a hill

If that were the case I would be able to charge my Battery going downhill to work and travel home uphill on that charge. Free energy……. There will always be friction and transmission losses amongst others. There is no such thing as a free lunch as they say. 

[AJones]

On 9/18/2023 at 5:00 PM, Nicolai said:

Like you, I will be doing most of my driving locally (60 miles a week in total to and from work). Once every other week, I go a total of 140 miles (70 miles out, 70 miles back) to visit my parents. But other than that that the engine would only be required for holiday trips and such. As such, the PHEV is the better choice compared to HEV.

If that's the typical mileage you are doing, you could skip hybrids all together and jump to a full EV as that's well within the capability of most recent EV models, unless you're needing a hybrid for towing a caravan.

[Roker]

13 hours ago, Flatcoat said:

If that were the case I would be able to charge my battery going downhill to work and travel home uphill on that charge. Free energy……. There will always be friction and transmission losses amongst others. There is no such thing as a free lunch as they say. 

That is the whole point of a hybrid, I acknowledge that there is frictional losses but the extra losses with weight will be negible compare to the whole car. We wouldn't need an engine if we got 100% energy back

[ColinB]

On a few occasions in my HEV I've noticed that after a few downhill sections the ICE has fired up to give engine braking as the small Battery is at 100%. A PHEV would have more potential capacity to make use of the regen, rather than wasting the energy

[Flatcoat]

5 minutes ago, ColinB said:

On a few occasions in my HEV I've noticed that after a few downhill sections the ICE has fired up to give engine braking as the small battery is at 100%. A PHEV would have more potential capacity to make use of the regen, rather than wasting the energy

When the Battery isn’t fully charged, yes. I did add 4 miles of range coming down a steep descent from Tittisee to Freiburg last summer. Otherwise a descent rarely adds more than 1 mile range. 

[TonyHSD]

When Toyota hybrids got their traction Battery fully charged as a result of going downhill they start the engine to reduce this Battery charge to more appropriate levels. The engine may even start after you have finished your descend and you are driving on flat road or being stationary.
With the time and mileage when your traction Battery gets old these events of quick charging and discharging will become very obvious and happens more often, this is the most common sign of worn out traction battery in these cars. 
When the car is new the battery level will remain around the middle most of the times or around 50% if checked with an app. 
All that strictly about hev .
PHEV might be similar if we exclude the larger size and the ev only range,, but since I have no experience with those yet I can’t say for sure. 

[Nicolai]

16 hours ago, AJones said:

If that's the typical mileage you are doing, you could skip hybrids all together and jump to a full EV as that's well within the capability of most recent EV models, unless you're needing a hybrid for towing a caravan.

Based on my mileage, yes I could get an EV. I'd just like to stick with Toyota and the boot of the BZ4X is too small. The boot of the RAV4 Plugin is a little more practical but you're settling for only PHEV and not full EV which will, undoubtedly be cheaper to run. The BMW IX1 is full EV and range is OK for me but not sure it's reliable enough.

[TonyHSD]

Evs has started to decline in sales and popularity around the world and especially uk and Europe. Many who bought those are going back to ice and hybrids. Unless highly necessary to be a full electric car because of town centre commuting the hybrids are better option. 
Today is official, government are talking about extension of the ice and hybrids new car sales past 2030. 
Even with current rate of new bev adaptation we are heading into an environmental  disaster and it’s only a matter of time someone like journalists, a body or authority rep to trigger a new Battery gate similar to diesels back in 2014. If that happens which is very likely imo. The bev will be doomed. 
The bev only has one benefit over others, no tailpipe emissions. Which is a huge step forward but two steps backwards in wider field seen, because of current Battery technology and recycling possibilities. 
Future of automobile is not as is seems to be. 

[ernieb]

3 hours ago, TonyHSD said:

When Toyota hybrids got their traction battery fully charged as a result of going downhill they start the engine to reduce this battery charge to more appropriate levels. The engine may even start after you have finished your descend and you are driving on flat road or being stationary.
With the time and mileage when your traction battery gets old these events of quick charging and discharging will become very obvious and happens more often, this is the most common sign of worn out traction battery in these cars. 
When the car is new the battery level will remain around the middle most of the times or around 50% if checked with an app. 
All that strictly about hev .
PHEV might be similar if we exclude the larger size and the ev only range,, but since I have no experience with those yet I can’t say for sure. 

If I’ve fully charged my PHEV overnight and descend a step hill the ICE will fire.  It will initially take more charge as I figure the traction Battery even though it says full is not actually 100%. I’ve always assumed a major part of that is that the breaking effect of the regeneration is no longer available.

[Flatcoat]

47 minutes ago, ernieb said:

If I’ve fully charged my PHEV overnight and descend a step hill the ICE will fire.  It will initially take more charge as I figure the traction battery even though it says full is not actually 100%. I’ve always assumed a major part of that is that the breaking effect of the regeneration is no longer available.

Traction batteries on any hybrid are never actually full when supposedly fully charged. There is an upper and lower buffer to help manage Battery life.