Engine starting down hill

[Rosgoe]

I can’t understand why the engine starts on the hybrid corolla when the traction Battery is fully charged going down hill it then stops after say a couple of minutes and goes into ev if the engine starts is this not putting more charge into the Battery than is required?

If the Battery is fully charged then it should go into ev with your foot of the accelerator pedal incidentally this is with the climate control on low with ac off also when it does this you get a slight surge as though it wants to accelerate and you have to brake harder.

 

 

[Cyker]

Probably one of:

a) Engine is too cold - It will fire up the engine to get it at least a bit warm; Usually does this when you first start the car too.

b) HVAC temp set higher than ambient - The engine will be run if the car needs a heat source to heat the cabin to the set temperature; It will even do this without charging the Battery or powering the wheels.

c) Traction Battery is full and the car is slowing down - Normally the car will do some low-level regen when the accelerator is released, but if the Battery is too full to accept charge, it reverts back to what a normal car does, and uses the engine to simulate engine braking instead of the regen, also does more this when braking with a full traction battery.

 

c) is mostly speculation as I've never gotten mine to get more than 3/4 charge so far so I don't have any first hand experience - a) and b) I've experienced first-hand.

[TonyHSD]

Ice kicks in when going downhill and your hybrid Battery is full to maintain charge levels as when engine is running can charge but also discharge your hybrid Battery. If you hit EV button the car will refuse to go into ev mode and message on the display will pop up as ev mode currently unavailable. Nothing unusual and happens to me often. 👍👌

[Devon Aygo]

1 hour ago, Rosgoe said:

I can’t understand why the engine starts on the hybrid corolla when the traction battery is fully charged going down hill it then stops after say a couple of minutes and goes into ev if the engine starts is this not putting more charge into the battery than is required?

If the battery is fully charged then it should go into ev with your foot of the accelerator pedal incidentally this is with the climate control on low with ac off also when it does this you get a slight surge as though it wants to accelerate and you have to brake harder.

 

 

The car has lower then normal rolling resistance so if you are going down hill normally ( not accelerating with throttle applied ) the car is effectively coasting and will gain speed if the Battery charge is low then the car car regenerate power into the Battery creating resistance and reducing the speed gain same applies if you brake normally the car will use increased regen to slow you adding power to the Battery , with a full battery the car is less able to regenerate power to the battery to stop the speed gain and help control the car, in this circumstance Toyota engage the engine effectively as a large air pump ( no fuel is added ) this creates resistance to aid in controlling the car this also helps reduce brake wear as with a full battery the car can't regen via braking so has to use friction braking instead 

[Rosgoe]

11 hours ago, TonyHSD said:

Ice kicks in when going downhill and your hybrid battery is full to maintain charge levels as when engine is running can charge but also discharge your hybrid battery. If you hit EV button the car will refuse to go into ev mode and message on the display will pop up as ev mode currently unavailable. Nothing unusual and happens to me often. 👍👌

It must have been the same with the auris I had but never noticed the engine starting as it never had the rev counter but yes you couldn’t put that into ev mode going down a long steep hill with a full Battery.

[Trewithy]

I have noticed this too and it is normal.  When you see the rev counter is showing the engine is spinning no petrol is being used, the engine is being spun by the hybrid Battery.  This is to use some of the power in the Battery to prevent it from being overcharged.  

[Bozz]

22 minutes ago, Trewithy said:

I have noticed this too and it is normal.  When you see the rev counter is showing the engine is spinning no petrol is being used, the engine is being spun by the hybrid battery.  This is to use some of the power in the battery to prevent it from being overcharged.  

It is a marvel of automotive engineering 

[twintopp]

even after a 450 mile round trip i have never seen mine more than 5 bars out of 8 .so have never seen a full hybrid Battery.

[AndrueC]

19 hours ago, twintopp said:

even after a 450 mile round trip i have never seen mine more than 5 bars out of 8 .so have never seen a full hybrid battery.

I've seen it a couple of times but it's normally rare. I saw it several times during my holiday in North Wales earlier this year. My B&B was just off the A5 at the 'top' of the hill down into the Conwy valley. Both times that I went down to Conwy the Battery was showing as full about the time I reached the A470 junction. On one occasion I took a really scenic route which meant going up to the moors even higher than the A5 then coming down steep country lanes. That time the Battery became full while I was still descending.

When full it was noticeable that the brakes were a lot sharper (presumably because they were using the discs all the time instead of charging the battery) and the engine kept spinning up while descending. I also noticed (as I have previously) that the car was very eager to enter EV mode, prepared to let me have more power without using the ICE and seemed to have more pep.

[Cyker]

I've yet to find a hill long and steep enough to get that much charge out of it - The most I think I've seen was maybe 6-7 bars out of 8, and ironically I got that on a very long uphill that forced the engine to run the whole way (I wasn't planting it, so it was charging the Battery the whole time)

I have to say, the ICE in the Mk4 is incredible - My friend was warning me that if the car had to rely on the ICE alone I'd soon find it annoying as it has to rev so much more when it can't get assistance from the electric motor, but so far  I've not found that at all in the Mk4; That little 3-pot seems to have plenty of pull whenever I ask for it, and I've not found it wanting for power so far!

 

[dannyboy413]

On 11/7/2021 at 9:28 PM, twintopp said:

even after a 450 mile round trip i have never seen mine more than 5 bars out of 8 .so have never seen a full hybrid battery.

I never get chance to do a 450 mile round trip, but, in general, I only ever see 5 or 6 bars. I did do a post a few months ago about never seeing a full 8 bars and the general consensus was that this was normal.

[Cyker]

Yeah, the car seems to try to keep the charge as near 50% as possible - If you go over it uses more EV, if you go to 3 or less it always fires up the ICE (Very annoying if you're in stationary traffic! I wish I could force it to drop to 2 or even 1 bar when stationary before starting the engine...)

Very good for Battery life - Should outlast pure EV's!

 

[Anthony Poli]

I haven't had the engine start on a decent.

I have seen the Battery only maxing out on a long decent in the early days, but use B mode to go downhill.

I regularly see the car not going into EV with a full Battery, after slowing down on a slip road.

[TonyHSD]

11 hours ago, Cyker said:

Yeah, the car seems to try to keep the charge as near 50% as possible - If you go over it uses more EV, if you go to 3 or less it always fires up the ICE (Very annoying if you're in stationary traffic! I wish I could force it to drop to 2 or even 1 bar when stationary before starting the engine...)

Very good for battery life - Should outlast pure EV's!

 

Yeap, Toyota hybrids batteries are made to charge and discharge a million times, also when Battery shows max bars (full) actual charge is around 78-80% Tbh the self charging hybrids are more of an ice cars with greatest stop start system than electric vehicles, this is important to be differentiated. 👌 These are also best replacement for diesel cars and long trips. To date over 190k miles and 11 years both original batteries with good numbers when measured,I hope to get another 100k miles before eventually a replacement of the Battery or the car will be necessary  🤭✅

[Cyker]

I think you'll get that easily - We have Prius Mk2 people here still on the original Battery!