hybrid battery continually charging even when full

[steviehay]

I have a 2019 toyota corolla sports tourer and recently ive noticed that the hybrid Battery continually charges even when it seems full. Of course this means that my MPG has gone down and continues to do so. Any thoughts would be appreciated

[Stopeter44]

Just now, steviehay said:

ive noticed that the hybrid battery continually charges even when it seems full.

How do you see that ? For instance, when the Battery on my Yaris is full the green and yellow arrows on the "flow" diagram still show, but the Battery is not really being charged. With current cold weather MPG would be expected to decline.

[steviehay]

Well on the Battery indicator it shows when the engine is charging the Battery, can also hear it kicking in while idling, and the MPG has been steadily decreasing from 51.5 a few weeks ago and now siting at 48.6

[Jiff]

Same as mine, winter mpg is always lower & I think the engine runs just too keep itself and the occupants warm. 

I don't worry about it but have noticed a change in the charging / e running cycle, I wonder if the computer has been reprogrammed as they've found a more efficient regime 🤔

[steviehay]

Well it never happened last winter

[Cyker]

It's probably the heater; The car will run the engine much more than normal while it's trying to heat the car up.

On my Yaris, if the engine temp gauge is less than 4 bars and the heater is set to more than 18C it will run the engine continuously, which tanks the mpg if I'm crawling through traffic.  

[yossarian247]

Our cars do it in cold weather too. The engine isn't running to charge the Battery, its to heat the heater. The colder the weather the worse the MPG, same on any petrol or diesel car not just hybrids.

[Cyker]

It's one unfortunate side effect of being so efficient - The more thermally efficient the engine, the bigger the hit it takes in winter. Petrol cars see much less variation as their base efficiency is pretty awful to begin with, but you can see much bigger swings with diesel and hybrids.

If you primarily do long journeys the effect is greatly lessened as the engine spends more time nice and hot, but short journeys will crater the average mpg.

Using the heater just exacerbates the problem as it's sucking what little heat the engine generates out and into the cabin instead, so the engine can't stay at operating temperature.

With the hybrids, you can mitigate it by not using the heater, which I was doing initially as I wanted to stay in the 70's mpg, but I've decided on balance that being able to feel my face and also not see my breath in the car is worth spending a few mpg!   

[yossarian247]

I think the reason even the lowest spec Corolla comes with heated seats is so that use of the air blower heater can be minimised to preserve fuel economy. Well in theory anyway. In this weather I just drive around with the heated seats on max and the heater on full blast too!

[Cyker]

That's why I'm so mad the Yaris doesn't even get an option for heated seats! I think every other model gets them, even the smegging Aygox! Why Toyota whyyy! In fact, Why Toyota GB, Whyyyy - The Euro-spec ones can have heated seats! Why can't weeeee?? I'm so cold...

They even left it out of the new 130HP models coming up so I know they're doing it deliberately!!

I can't even install a janky 12v heated seat pad as they all tie round the seat, but the Yaris Mk4 seats are full of explosives and I don't want to put any straps in the way of said explosives!   (I tried not using the straps and the whole thing, and me, just slid off the seat as soon as I braked so decided probably wasn't a good idea!   )

[steviehay]

Its not the heater, on the Battery screen it clearly shows that the engine is putting power into the Battery even when its full. I'll just take it to the dealership see if they can find out whats happening.

[TonyHSD]

1 hour ago, steviehay said:

Its not the heater, on the battery screen it clearly shows that the engine is putting power into the battery even when its full. I'll just take it to the dealership see if they can find out whats happening.

Hi, 

you don’t need to worry about it or anything else to do.  
It is a normal hybrid behaviour during winter season.
The colder the temperatures are the longer time the engine will work.
There are also different scenarios where the engine will run even with full Battery, it so not only limited to charge or heat, it is to discharge too or balance the voltage between the different cells.
Another event in cold or hot weather you may notice is that the engine will engage more often and stay for longer to take off any excess load from the Battery, all that to extend the life and prevent any accelerated wear. 
If no warning lights on dashboard, then there is nothing wrong with the car in most cases. 👌👍
 

[Chas G]

I have taken a different approach. I got tired of looking endlessly at the dynamic graphic showing what the engine, motors and Battery were supposedly doing.

I changed the screen to static audio display. 

Ps when I come down Ducks Hill on my way back from Watford my hybrid Battery normally shows it is full to overflowing. Shame it can't put more of it into the 12 volt Battery.

[Bos]

On 1/19/2024 at 12:32 PM, steviehay said:

Well it never happened last winter

It is a lot colder this winter compared to last, well it is around here in South Devon.

[Don Mac]

21 hours ago, Chas G said:

Ps when I come down Ducks Hill on my way back from Watford my hybrid battery normally shows it is full to overflowing. Shame it can't put more of it into the 12 volt battery.

Ducks Hill, I know it well...

Look on the bright side: if the engine is spinning whilst you're going downhill it's probably clearing out the particulate filter. 🙂

[taxidriver50005]

Depending on on how and we're you drive the car might also be trying to regenerate the petrol partical filter, not 100% on how these work on Toyota but most cars try to load the electrical system so to make the engine work harder and generate more heat in the exhaust system, so it would stand to reason charging Battery would fall into the making the engine work harder. 

[Don Mac]

48 minutes ago, taxidriver50005 said:

Depending on on how and we're you drive the car might also be trying to regenerate the petrol partical filter, not 100% on how these work on Toyota but most cars try to load the electrical system so to make the engine work harder and generate more heat in the exhaust system, so it would stand to reason charging battery would fall into the making the engine work harder. 

As I understand it:

Diesel particualte filters clear out when the engine is under load, so they're running hot. (e.g. long run at 40+ mph speeds)

Petrol (gasoline) particulate filters clear out when the engine is running 'lean' (no load), so there is more oxygen in the exhaust. (e.g. lifting your foot off the throttle going downhill)

[TonyHSD]

This about particulate filter cleaning process, is that noted in any Toyota official documents or it’s just another myth? 
My car from 2010 does behave exactly the same way as yours from 2019 onwards, I do believe it also has a particulate filter , the second cat in the exhaust system if that’s yours too or it is something else in addition to all above. 
I am questioning these about GPF regeneration as in many cases the strange  behaviour is on a brand new cars with ultra low miles, perhaps their gpf’s hasn’t been clogged up with soot of yet. 
 

[Don Mac]

1 hour ago, TonyHSD said:

This about particulate filter cleaning process, is that noted in any Toyota official documents or it’s just another myth? 

The thing with petrol (gasoline) particulate filters (GPFs) is that they are nowhere near as prone to clogging as the diesel ones, it almost never happens.

As long as you lift your foot off the accelerator every so often the extra dose of oxygen making it through the engine into the exhaust (which heats up quicker in a petrol engine) will be enough to burn off the particulates. Direct injection petrol engines produce more particulates than port injection, but still nothing like as many as a diesel. No special cycle or behaviour (the long 'blast' run) should be required.

A GPF is smaller and cheaper than the diesel equivalent and shouldn't need replacing. A normal driver shouldn't have to worry about them.

[Cyker]

Hmm I forgot about the GPF thing.

I had some interesting observations in my Mk4 last year when my windscreen got cracked; Because going at speed seemed to make the crack grow alarmingly, I changed some of my routes to go through the torturously slow and gridlocked roads I normally avoid.

After a couple of days of this I noticed the engine would just continue to run for no reason, sometimes even with the HVAC off and when the car was being moved by the electrics - Because the HUD has a tacho it's very easy to see when the engine is running as the RPM isn't zero  

A few other members had reported this sort of thing a few weeks prior and put it down to the engine trying to regen the GPF. I found it curious mine had only started doing it now, and can only put it down to the engine running much colder and less frequently, due to my slower routes, somehow causing a more rapid build up of particulates.

One member found if they drove along in B-mode for a few minutes, that stopped the weird engine-running-for-no-reason behaviour. I tested this and found it seemed to work as long as you coasted in B-mode for long enough.

The theory was the engine-running-for-no-reason state was caused by it trying to regen/burn-off the particulates in the GPF, and B-mode was allowing the engine to pump much more oxygen into it and allow it to do so easier (Normally the engine just shuts off when you let go of the accelerator, so under normal circumstances, no oxygen would go into the exhaust - In B-mode the engine will happily spin up to 4000rpm with no combustion, sending plenty of fresh air through the exhaust!)

[Don Mac]

1 hour ago, Cyker said:

The theory was the engine-running-for-no-reason state was caused by it trying to regen/burn-off the particulates in the GPF, and B-mode was allowing the engine to pump much more oxygen into it and allow it to do so easier (Normally the engine just shuts off when you let go of the accelerator, so under normal circumstances, no oxygen would go into the exhaust - In B-mode the engine will happily spin up to 4000rpm with no combustion, sending plenty of fresh air through the exhaust!)

That sounds convincing to me.

I'm going to try the B-mode trick next time I notice 'unnecessary' engine running (why didn't I think of that...?)

What we need is a Toyota technician/engineer to tell us whether we're just making this up......

[yossarian247]

I've wondered whether our cars have GPFs and found it difficult to find a definitive answer, so I paid 4 Euros for an hours access to the toyota-tech.eu site. It appears that (as far as the Corolla goes) the 2.0 M20A-FXS engine had a GPF from the start, whereas the 1.8 2ZR-FXE engine only got a GPF from October 2020 onwards. 

[Roy124]

I have been doing a regular 5 min run to the school bus and from idle curiosity had the display set to the energy flow.

Starting I had the AC off.  At the car park the car was up to temp and we sat in Ready mode.  The HV showed 7 bar.

Both seat heaters were on.  I switched the AC on and the system fired up.  The HV bars dropped then the engine kicked in but there was no energy flow to the HV.

[TonyHSD]

Perhaps for a third time I can say that the engine is running to maintain the Battery charge which does not mean charging only but also discharging. And when this happens not necessarily the hybrid energy flow meter will show correctly what is going on. 
I am experiencing a dead hybrid Battery at the moment with my car and constantly monitoring with an app what is going on behind the scene, very different from what we see on dashboard. There are constantly changes between charging and discharging cycles while stationary, when driving at constant speeds or while under acceleration. These cars are very smart, but they does not show us all that happens behind the curtains, no need to worry about it.