12v battery maintenance, issues, etc.

[Max_Headroom]

A lot of people assume you connect both batteries together and it doesn't matter which lead you connect first, that is why people often cause damage to modern cars.

 

 

[Mojo1010]

Recently came back from 10 days being abroad. Car starts no problem, though the weather has been milder than usually at this time of year. The handbrake were a bit sticky at the wheels to begin with. 

[anchorman]

4 hours ago, Mojo1010 said:

Recently came back from 10 days being abroad. Car starts no problem, though the weather has been milder than usually at this time of year. The handbrake were a bit sticky at the wheels to begin with. 

My garage is level so I tend to leave the car in park with the handbrake off.  At least I do if I can remember 🙄

[Mojo1010]

I don't have that luxury with street parking 🙄

[Roy124]

Same 12 days here, two short journeys then laid up in car park, then two more moves a mile or so. 

Today hybrid Battery was at 50% but no 12v problem. 

[Max_Headroom]

Rather than start a new thread i thought i would ask here.

I am seriously thinking about buying a cross in the not-too-distant future but this 12v Battery thread is a bit off putting as my commute to work is only a few miles daily, can i ask the best way of keeping the 12v Battery charged i.e. if doing short journeys every day go for a longer run on day 3 to top it up, we go to the next town (16-mile round trip) a couple of times a week to do a supermarket shop and visit family would that do it?

 

[Mojo1010]

55 minutes ago, Max_Headroom said:

Rather than start a new thread i thought i would ask here.

I am seriously thinking about buying a cross in the not-too-distant future but this 12v battery thread is a bit off putting as my commute to work is only a few miles daily, can i ask the best way of keeping the 12v battery charged i.e. if doing short journeys every day go for a longer run on day 3 to top it up, we go to the next town (16-mile round trip) a couple of times a week to do a supermarket shop and visit family would that do it?

 

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 👍

[Max_Headroom]

Thanks I was aware the 12v Battery doesn't start the car as in a non hybrid car but having read so many posts about short journeys killing the 12v Battery I was worried my short daily commute wouldn't help.

[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.