12v battery maintenance, issues, etc.

[CPN]

1 hour ago, Mojo1010 said:

The 12v battery is not needed to start the car,

That is just not true. The 12v Battery is exactly what is used to "start" the car. (for activating ECU's and the HV safety contactors)

1 hour ago, Mojo1010 said:

your driving for a few miles daily will be sufficient to top it up, especially with the long journey. All good 

That is true. 

[Cyker]

He just meant it isn't needed to crank the engine like in a normal ICE car, so it doesn't need to deal with the massive current draw when you start the car, that would then require replenishing.

The relatively low impact/power draw of the hybrids mean the 12v Battery has a much easier life than in normal cars, although that advantage does seem to have been off-set by the weird cyclic charging schedule and smaller capacity.

[CPN]

Right. Having said that, I have watched my 12v at 12.2v, just before pressing start, dip to 11.8v just as the start button is pressed. (this cold weather) That is quite an appreciable dip in voltage for a "normal" start ... 

[Roy124]

1 hour ago, Mojo1010 said:

You got nothing to worry about. The 12v battery is not needed to start the car, your driving for a few miles daily will be sufficient to top it up, especially with the long journey. All good 👍

I don't think 'a few miles daily' is actually true. The important issue is having the car on Ready mode for 30 minutes at least once a week. 

If you drive a few miles, say 4 or 5, you might only be in Ready mode for 10 minutes. 

One thing I don't know about Hybrids is whether the 12v Battery can run in deficit.  Can the HV Battery replace the 12v services drain when all services are selected, heaters, wipers, lights etc.?

[Mojo1010]

What I meant was the 12v doesn't crank the engine therefore it doesn't depletes it, so it only require a top up. 

My understanding is that the HV Battery takes the load in general and charges the 12v. There are members sometimes only drives once a week in the winter and the car starts fine, though the car is garaged. So everyday driving there isn't anything to worry about, especially 2x longer trips. 

[Max_Headroom]

1 hour ago, CPN said:

That is just not true. The 12v battery is exactly what is used to "start" the car. (for activating ECU's and the HV safety contactors)

I think you are being a little pedantic as i did say -

Quote

I was aware the 12v battery doesn't start the car as in a non hybrid car 

I imagine 99% of members reading this got what i meant.

[Cyker]

1 hour ago, CPN said:

Right. Having said that, I have watched my 12v at 12.2v, just before pressing start, dip to 11.8v just as the start button is pressed. (this cold weather) That is quite an appreciable dip in voltage for a "normal" start ... 

Yeah, I think TonyHSD said that was likely all the pumps that are normally powered by the engine in ICE cars that are driven by electric motors, with the largest draw most likely being the brake servo vacuum pump., and that sortof leads on to...

 

1 hour ago, Roy124 said:

I don't think 'a few miles daily' is actually true. The important issue is having the car on Ready mode for 30 minutes at least once a week. 

If you drive a few miles, say 4 or 5, you might only be in Ready mode for 10 minutes. 

One thing I don't know about Hybrids is whether the 12v battery can run in deficit.  Can the HV battery replace the 12v services drain when all services are selected, heaters, wipers, lights etc.?

So this is one thing I haven't gotten my head around - I assumed the 12v Battery was just used to power up the main computers and close the contactors, then the traction Battery would take over and supply power to the whole 12v system and charge the 12v Battery, but now I'm not so sure as there is definitely a cyclic pattern on the 12v where it goes to 13-14v, then back down to 11.something volts, then back again, during normal use.

Powering on the e.g. the AC system, headlights etc. seems to keep it at a higher voltage more, so it does seem like when there is lower demand it might be shifting all the power load to the 12v battery for a bit until it drops to a certain level, then takes over again while slowly charging it back up, instead of just constantly supplying power to the whole 12v system like an alternator would.

I wonder if there is a paper somewhere that documents how it works!!

 

[RobertR]

Yes, it's. 

Only AC electric compressor is powered directly from the HV battery( through Inverter ), everything else is 12V and inverter constantly charging 12V Battery + auxiliary load (heated seats, headlights, wipers etc).

 

Yaris Cross Hybrid hvdm.pdf

[anchorman]

[AisinW]

12V Battery main job is only to start the computer and contactors.  It is rated about 60Amps when it start the car.  After that The DC to DC converter supply the whole 12V lines including recharging the auxiliary Battery. 

If the 12V Battery is depleted, it is when the car is off.  One of the cause is the Emergency-Call-System that keeps on for few hours in all new Toyota and cause battery drain especially on small Yaris.  I believe there is a TSB to reprogram the ECU to reduce the E-call time, etc.   Some 2.0L Corolla even got bigger AGM battery as the solution. 

[Roy124]

AisinW, when you say 60AHr Battery are you talking of a specific fit for one model? 

My MY19 Corolla 1.8 had a 35AHr Battery until my dealer fitted a 42AHr one.  I haven't looked to see what is fitter to my Yaris Cross. 

[AisinW]

4 hours ago, Roy124 said:

AisinW, when you say 60AHr battery are you talking of a specific fit for one model? 

My MY19 Corolla 1.8 had a 35AHr battery until my dealer fitted a 42AHr one.  I haven't looked to see what is fitter to my Yaris Cross. 

60 Amps is the amperage of drawing current not Battery capacity. Yaris have 35AHr capacity and 272 Amps CCA. So, the new good Battery can deliver more than 4x amperage the car need. Over time, it gets weaker from aging and sulphation of the electrodes, especially the cathode PbO.  If you maintain the car well and drive regularly, the voltage never drop below 12V. Generally, permanent damage occurs whenever the open voltage drop below 11.8V, you cannot recover the damage but the Battery will still usable flr many more years. It is all because the car only need 60 Amps and even my 7 years old battery still works fine although the capacity is not like new anymore.  My open voltage after fully charge and then turn the headlights for 1 minute to remove surface charge is now 12.6V with Lidl 5A charger.  When it was new, it is about 12.8V.

Corolla 1.8 has regular flooded battery and has higher capacity than Auris or Yaris AGM. Wet cell is much cheaper, about 1/4 price and easy to find upgraded size because it has enough room for bigger battery in the engine bay. 

[Jimota]

This was a topic that I was hoping to make a constructive comment on.  However, the very detailed explanations on Battery maintenance has left me with the conclusion that I don’t have sufficient knowledge on this matter and I’ll leave it to better informed members to give further updates.  

[AisinW]

I think few things we can do to help preventing Battery depletions and leaveus stranded. 

1.  Get decent 12V charger like the one Lidl or Aldi sold with 5A rating.  Hooks it up anytime we leave the car for weeks.

2. Buy Battery pack jumper, something that is certified by independent agent like TÜV. 

3. Visit dealership and ask for any Technical Service Buletin TSB related to the Battery 12V,such as Emergency call.

4. Get Volt meter or OBD2 (Veepeak £15 in Amazon) and install Torque Lite (freeware) that can check the status of 12V battery when we turn it on to ACC mode.  

I hope those help us. 

[Max_Headroom]

I thinks its a disgrace that Toyota are getting away with selling vehicles that you cannot leave for one to two weeks without having to attach something   to stop you worrying the thing may not start the next time you want to drive it.

 

Another day another how to stop the 12v Battery going flat question -

 

[Graham47]

20 minutes ago, Max_Headroom said:

 ……you cannot leave for one to two weeks without having to attach something   to stop you worrying the thing may not start the next time you want to drive it.

 

 

They aren’t !
Mine has been left for 5 weeks (twice) and 3 weeks (twice) without issue.  I don’t have access to charging nor do I possess a solar charger.

 I suspect many of the ‘fears’ you highlight in your post are as a result of (new) owners reading this thread !!

[AisinW]

Look, there aare  indeed some issues with the implementation of emergency call and draw some current hours after the car is off. There is  probably a TSB to resolve that issue.  My car Battery lasted at least 8 years in all hybrid I had since 2006. Identical with the one  Yaris and Auris have, Yuasa S34B20R 35AHr small tiny AGM.  Off course, we do not to worry if you only leave the car for 2 weeks but removing the D/C CUT fuse will prevent any unintended Battery draining like we leave the smart keys near the car and idiotic Emergency call standby time.  

Like I said before, any Lead-sulphate Battery will permanently degrade if the voltage drop below 12V. our pro-active acts  will help. Once the battery is ever drained, cannot start the car, the permanent damage has already done. The battery is not the same as it was and probably had capacity drop for 25%.  If it is not far too long and low, some desulphation process (charging the battery slowly and long above 14.8V) may recover some of the life of the battery and can still be used for few more months or years.  Just, do not expect too much once we ever let the battery far gone below 12V.  Desulphation eats/etch the electrodes and sometimes boil the electrolyte too and we cannot add destiled water to AGM battery. 

 

[Max_Headroom]

20 hours ago, Graham47 said:

They aren’t !
Mine has been left for 5 weeks (twice) and 3 weeks (twice) without issue.  I don’t have access to charging nor do I possess a solar charger.

 I suspect many of the ‘fears’ you highlight in your post are as a result of (new) owners reading this thread !!

The thread is 8 pages long and there are many examples of owners leaving their cars for a few days then having problems its obvious if you drive often enough you will have no issues but i bet the sales men/women don't mention this when they are selling you the car, i leave my second car parked up weeks at a time and it never fails to start this really should have been sorted when it became apparent it was an issue.

[Roy124]

Max, indeed.  When I retired I laid my Escort Cabriolet up for some months. Come late Spring it would not go. 

Started OK but the handbrake was rusted on. 😅

[Roy124]

As matter of interest I just checked my YC.  The voltmeter gave 12.8v (it was driven yesterday).  I plugged in the CTEK anyway and the AGM steps 1 and 2 came on immediately.  Step 2 is increase the BV to 12.6.

Almost immediately after step 3 came on which is increase to 14.5v.

Once it has run through the steps it will allow the voltage to decay and then boost.  Too cold to stand out and wait. 

[Max_Headroom]

3 hours ago, Roy124 said:

Max, indeed.  When I retired I laid my Escort Cabriolet up for some months. Come late Spring it would not go. 

Started OK but the handbrake was rusted on. 😅

You mean you forgot to put bricks under the wheels and leave it in gear with the handbrake off  😉 

[Roy124]

15 minutes ago, Max_Headroom said:

You mean you forgot to put bricks under the wheels and leave it in gear with the handbrake off  😉 

Quite.  Never occurred to me as it was in my garage and I had never laid up a car before. 

Many years ago I did have to leave my Ford Anglia for 3 months.  It was left on a hangar as and I only had time to reclaim road tax and change the insurance. When I went back it was simply a question of starting and driving off.  I don't (60 years on) remember checking tyres etc.  The car was only 6 month old and I had no experience. 

 

[AisinW]

On 12/11/2022 at 4:06 PM, Roy124 said:

As matter of interest I just checked my YC.  The voltmeter gave 12.8v (it was driven yesterday).  I plugged in the CTEK anyway and the AGM steps 1 and 2 came on immediately.  Step 2 is increase the BV to 12.6.

Almost immediately after step 3 came on which is increase to 14.5v.

Once it has run through the steps it will allow the voltage to decay and then boost.  Too cold to stand out and wait. 

Most Smart Charger (CTEK, LIDL, ALDI, NOCO5, Bosch, etc.) have many steps of charging and the cutoff is usually pretty high about 14.5-15V.  Basically, it charge until full but the float voltage of the Battery after surface charge is removed (headlights on for 1 minute), the open circuit voltage is usually about 12.5-13V in good working AGM Battery.  The problem shows up more clearly when we put a load on it.  So, you can turn the heater seat ON, blower motor at max and headlights on for 15 seconds and read the voltage reading. It should be more than 10V for a good Battery. Typically the voltage of the battery with the Ignition ON/ ACC mode (2x pressing power button without pressing brake pedal) for normal battery is 11-12 V after we fully charge the battery.  Below 11V in ACC mode means the battery is at the end of its life. 

[RobertR]

Watch this video and you wii everything about the 12v Battery in your hybrid. https://youtu.be/_V9PiOpaxyE

[Tonanti216]

I have a 2021 model and have exactly the same problem as Joby1 - 

I don't use the car every day but on many occasions, particularly during lockdown etc. the car did not get moved.  

It seems odd to me that I am the one to blame for not "keeping the Battery charged up"  if you have to jump start it and then leave it on charge overnight so that you can be sure it'll start every time.  I'm starting to question my judgement when I decided to upgrade my old 2012 Yaris, so faithful and sturdy for this temperamental "new kid on the block"!