Overheating hybrid battery when i go downhill...

[marten88]

Hello. Can you help me or explain it?

When i am going oit from big hill down, hybrid Battery is Very often full charged wih all symboly or icons on displey.  Then is recoperations off, automaticaly is using motor.

 

Problem is,  hybrid Battery is then automatically discharge to min 3 icons on displey And motor is still on. Its about 15-20 mins. Then is recuperation again on and my hybrid Battery is charging again.

 

[Yugguy1970]

This is what it's supposed to do.  On normal driving it will stay 3 to 4 bars, about half full, charging and using the Battery as it needs to, starting and stopping the engine as it needs to.

A long downhill would add charge but then it will just get used.

[marten88]

Before it is fully charged i turn on heating seats, all what I can on to reduce maximum energy but in Prague we have a lot of long downhills so i think better is to buy for example Rav4 or Camry with bigger capacity of hybrid Battery. 

[flash22]

i think you are misreading the information, no the Battery is not overheating, and its not using braking regeneration you can not overcharge or make the Battery go flat

the diagram shows the car is using both the electric motor and petrol engine to drive the wheels and recharge the Battery

your chart tells you that you are getting over 100km/l combined fuel economy

 

this is usual behaviour for a hybrid

[Derek.w]

If it was overheating then it would throw up a charging system warning light.

(red Battery light)

[TonyHSD]

That’s normal behaviour, when you are going long downhill the Battery gets fully charged, then force discharge and then repeat over and over again , this is how the system has been designed to work. Max Battery soc 80% , even with some apps if you monitor this event once the Battery reaches 79% becomes red coloured and the battery cooling fan goes up in speed, they have 6 levels. If you drive on ev only also heats up the battery. Basically the battery gets hot when has been used more in both processes charging or discharging. 

[marten88]

Aha. So 

1 ) sometimes from long downhill is Battery realy fully charged,  then as you said, Battery is going all  discharge to,,minimum,, in case Corolla hybrid to 3 icons on displey. And that time for freezing Battery from fully charge it can be about 15 minutes then it again is using recuperation...

 

2. ) sometimes from long downhill is battery ,,almost,, fully charged, without 1 icons on displey,  then is not activation for ,, fully discharge. And recuperation can continue do maximum if There Will be next downhill.

[TonyHSD]

40 minutes ago, marten88 said:

Aha. So 

1 ) sometimes from long downhill is battery realy fully charged,  then as you said, battery is going all  discharge to,,minimum,, in case Corolla hybrid to 3 icons on displey. And that time for freezing battery from fully charge it can be about 15 minutes then it again is using recuperation...

 

2. ) sometimes from long downhill is battery ,,almost,, fully charged, without 1 icons on displey,  then is not activation for ,, fully discharge. And recuperation can continue do maximum if There Will be next downhill.

That’s right , and when you see fully charged all bars up to top that means 80% checked with the app. This app actually very nice if you want to play with, you can look hybrid Battery individual cells, voltages, deviation, charge and discharge rates, do some tests as well. I usually don’t like to play much but when servicing and have time plus showing valuable information. The picture above is from when I changed engine coolant and did bleeding the system I needed to see coolant temperature and if thermostat works as it’s should, you can see the app shows all temperatures of engine , inverter, cabin, Battery. Cool stuff 👌👍 App is called Hybrid assistant on android, and another one called dr. Hybrid. I also use Carista obd 2 reader from Amazon. If anyone wants to buy and test it’s own car. 👍

[marten88]

Thank you so much ;-)

[King Crimson]

I had experienced something similar when on a trip last summer, there was this road that was 90% downhill and then another 10% uphill, this resulted in the Battery being fully charged and the motor came in to discharge some of the Battery and it started revving all the way up to 5000 rpm. Not really a pleasant experience as the noise was very annoying while i was just going downhill and the car was just screaming as if i was accelarating when in reality i was braking the whole time.

[TonyHSD]

11 hours ago, King Crimson said:

I had experienced something similar when on a trip last summer, there was this road that was 90% downhill and then another 10% uphill, this resulted in the battery being fully charged and the motor came in to discharge some of the battery and it started revving all the way up to 5000 rpm. Not really a pleasant experience as the noise was very annoying while i was just going downhill and the car was just screaming as if i was accelarating when in reality i was braking the whole time.

With me happens on daily basis. First I was very surprised and unsure, then after I learned all about it and I am trying  not paying attention to it. 👍

[King Crimson]

1 hour ago, TonyHSD said:

With me happens on daily basis. First I was very surprised and unsure, then after I learned all about it and I am trying  not paying attention to it. 👍

Well what enjoy about hybrids is the car is silent most of the time and that makes for a relaxing commute to work, if i had to deal with the car screaming the whole time beause of my specific commute to work everyday then that would just defeat the purpose.

[Cyker]

The new ones really seem to try and keep the Battery at 50% (4 bars out of 8).

I can drive on MG2 until it drops to 3 bars, then it will switch to the ICE until it's charged up to 4 bars, then it will switch to MG2 again, rinse and repeat.

Only time it gets more than that is if I'm e.g. using the cruise control on the motorway, then I've seen it get up to 7 bars (!!) but even then I've never had it fill all 8.

[marten88]

Ah. So old version hybrid like my 2019 are quickly And easily get to 8 bars ( 100% on displej,  80% in reality)

[Cyker]

Well it might be different between the Yaris and the Corolla so I'm mostly just speculating!

The Corolla counts as a 'new' one tho' as it uses the current gen hybrid system as far as I know?

 

[TonyHSD]

I have recently experience something strange for a first time or it might be second but not so sure. The hybrid Battery went down to a lowest ever level, almost completely empty and the car continued to go on electric. I was expecting to see the warnings on the dash ⚠️🪫⚙️ and called an end of my cheap motoring, but then the engine kicked in and recharged the Battery as usual while I was driving slowly. The route I go is 30mph limit town lane and the car goes mostly in ev this obviously drains the Battery, however this time for some reason the car didn’t started the engine to recharge the battery on time. That was around 3 weeks ago, never happened again since then. All good for now🙂🚙

[marten88]

Yes. This is similar altnernative i was posted here.  It can be large downhill And fully charge for long time, then after downhill is discharging completely to minimum and long time is waiting to next recuperation.( probably because Battery is so hot and its cooling so much )

.... or as you write now,  you drive fluently in town almost straight distance, no hill, almost only on EV mode and then Battery is too discharged totaly and motor engine is on at the end not during drive. And then is long time to recuperation again to fill up 1 bar And more.  

[marten88]

Actually. After downhill was at car displey,,E,, recuperation but very small, Battery was  discharged from 8 bars to 3 bars ( pict1) and  didn’t started the engine to recharge the battery pict2) time from end of downhill And straight way was +-15 mins as is look on picture. 

[Derek.w]

Some of the diffrance is down to new modle as the spec was changed.

I seldom see 4 lights off on Battery display its usually 3 and all lights 8 light on at 90% and above.

Down hill I use B mode if its a long downhill run.

[Derek.w]

If it pulling the Battery that far down then I suspect it will not start if you stop and switch off.

If you unplug your add on monitoring device do you have the same results with the Battery indicator?.

[marten88]

5 hours ago, Derek.w said:

If it pulling the battery that far down then I suspect it will not start if you stop and switch off.

If you unplug your add on monitoring device do you have the same results with the battery indicator?.

If i Will stop with car And turn off during this discharging proces it Will stoped.

How can I unplug my add on monitoring device,  what you mean? I dont undestand

[Derek.w]

Your device that plugs into the ODB2 port is it effecting car self monitoring operation.

[marten88]

Hi. Now its in OBD2...  drive from downhill >>> maximum (69% in OBD2tools) Battery capacity ( 8 bars on  car display ) > going normaly or up to hill > Battery is discharging to ,,minimum,,  in OBd2 show 38% Battery capacity ( 3 bars on car displey)  not fluently discharging but totally disch.,  it takes from maximum to minimum always if battery has >= 69% about 10 minutes .then  charching Very slowly up. More on picts