Toyota: advice on 12v battery maintenance

[Yugguy1970]

We could be in danger of succumbing to car forum paranoia. 😆

How many actual reported Battery problems have there been?

[IanML]

It's not paranoia if they (the gremlins) are really out to get you 

[Nick72]

So if I don't drive (or switch to Ready mode for a while) my RAV4 PHEV in mid winter when it's like minus 5C for say 2 weeks because I'm on holiday or away on an international business thing is there a risk of the 12V Battery being dead?

If so that would be utterly ridiculous. A.k.a. shockingly Mod edit engineering. My 1999 Vauxhall Corsa started first time after 5 weeks of zero use in winter and it was 16 years old with the original Battery.

[Grompix]

7 hours ago, Nick72 said:

So if I don't drive (or switch to Ready mode for a while) my RAV4 PHEV in mid winter when it's like minus 5C for say 2 weeks because I'm on holiday or away on an international business thing is there a risk of the 12V battery being dead?

If so that would be utterly ridiculous. A.k.a. shockingly Mod edit engineering. My 1999 Vauxhall Corsa started first time after 5 weeks of zero use in winter and it was 16 years old with the original battery.

...my thoughts exactly - if the 12v auxiliary batteries in hybrids really are now so lackadaisical as to needing such tender care... 
Or whether owner-paranoia has a large part to play 🙄 
...although the voltage figures I was getting on my Battery seemed to indicate something tangible is/was going on rather than pure paranoia 😉 

[Grompix]

11 hours ago, IanML said:

That all sounds pretty good, although I am surprised that the low battery could drag the 14.2V down to 13.7.  That could just be a high resistance connection somewhere in the wiring, rather than a fault in the converter.

I'd be interested to hear whether it will keep things up to the mark in the future, or whether you will have to bring out the trickle charger again.

My thoughts were along similar lines (although not as qualified as yours Ian!), especially when I charged/topped-up the Battery three times with the car in 'READY' mode before getting the CTEK trickle charger.
Each time the Battery would appear fine then revert to its old ways of losing voltage - but it hasn't happened after the CTEK charge (yet!).  🙄

[Grompix]

10 hours ago, Yugguy1970 said:

We could be in danger of succumbing to car forum paranoia. 😆

How many actual reported battery problems have there been?

 

9 hours ago, IanML said:

It's not paranoia if they (the gremlins) are really out to get you 

Dr. Sod (and his law) always ready to strike! 😏 

[IanML]

9 minutes ago, Grompix said:

Each time the battery would appear fine then revert to its old ways of losing voltage - but it hasn't happened after the CTEK charge (yet!).  🙄

If you used the Recondition facility of the charger, it may have removed a fair amount of sulphation on the Battery plates, which should cause an improvement.

I don't use my old RAV4 much, so it gets a reconditioning charge about every 6 weeks.  I use a Battery condition meter to see the results, and with successive charges, the SOH (State of Health) has improved from about 60% (50% is reckoned to be the Replace point) to 94%, so it seems to work.

EDIT:  Submarines recondition their batteries before each patrol - they call it a "gassing" charge, so it isn't just marketing blether.

[IanML]

8 hours ago, Nick72 said:

So if I don't drive (or switch to Ready mode for a while) my RAV4 PHEV in mid winter when it's like minus 5C for say 2 weeks because I'm on holiday or away on an international business thing is there a risk of the 12V battery being dead?

If so that would be utterly ridiculous. A.k.a. shockingly Mod edit engineering. My 1999 Vauxhall Corsa started first time after 5 weeks of zero use in winter and it was 16 years old with the original battery.

Arrr, they don't make them like they used to.  The market for automotive lead/acid batteries demands a low price, so they scrimp on materials.

I think we should continue to complain about this problem, to encourage the car makers to modify their hybrid and EV auxiliary charging software, which would help maintain the auxiliary Battery in better condition.  Whereas a "pure" ICE car charges the Battery whenever the engine runs, the hybrid and EV models seem to only charge at widely separated intervals (probably to improve mpg or range).  I think this promotes Battery plate sulphation, which accounts for the problem.

Until that happens, our only recourse is the CTEK.

Anecdote: 18 months ago, I bought a two year old KIA Soul EV, and, within weeks, I had a flat auxiliary battery, with SOH only 56%, so I replaced it (it was the KIA original) but kept it in the garage, and occasionally gave it a reconditioning charge.  The SOH has recovered to about 80%, so I'm pretty certain the battery was not the problem, but the charging regime was.

[Yugguy1970]

I did wonder how a Battery could be rescued, I thought the chemical changes were irreversible.  Interesting, cheers.

What I meant was it's worth keeping an eye on things but not worrying about it day and night.  I can catastrophise with the best of them but I have Toyota breakdown so do I want to buy an expensive booster or be checking my Battery every week?   Or do I just want to ring them?

You don't hear large-scale reports of the millions of hybrid owners out there having issues.

[IanML]

There is another consideration.  Automotive batteries are designed to be kept topped up, which matches an ICE car, but not a hybrid or EV with software-managed charging.  It could be that a deep-discharge (i.e. recreational/camping) Battery would be a better match, but the challenge would be to find one of the right shape and size.  Another possibility is a lithium-ion Battery, which self-discharges at only 2% per month.  Of course, these batteries are more expensive.

[Yugguy1970]

That's the issue aye, it's all about cost.  If I had bought my RAv rather than PCP I'd be looking at better batteries yes.

[yossarian247]

3 hours ago, IanML said:

There is another consideration.  Automotive batteries are designed to be kept topped up, which matches an ICE car, but not a hybrid or EV with software-managed charging.  It could be that a deep-discharge (i.e. recreational/camping) battery would be a better match, but the challenge would be to find one of the right shape and size.  Another possibility is a lithium-ion battery, which self-discharges at only 2% per month.  Of course, these batteries are more expensive.

I've thought that too. It used to be said that deep-cycle leisure batteries were no good for automotive use as they don't have the cold cranking amps available, but of course with a hybrid it's not the 12V Battery that does the cranking so that shouldn't matter.

[Nick72]

5 hours ago, Grompix said:

...my thoughts exactly - if the 12v auxiliary batteries in hybrids really are now so lackadaisical as to needing such tender care... 
Or whether owner-paranoia has a large part to play 🙄 
...although the voltage figures I was getting on my battery seemed to indicate something tangible is/was going on rather than pure paranoia 😉 

If they just put one in twice the size it probably wouldn't break the bank or make any difference to volume.

[Nick72]

4 hours ago, IanML said:

Arrr, they don't make them like they used to.  The market for automotive lead/acid batteries demands a low price, so they scrimp on materials.

I think we should continue to complain about this problem, to encourage the car makers to modify their hybrid and EV auxiliary charging software, which would help maintain the auxiliary battery in better condition.  Whereas a "pure" ICE car charges the battery whenever the engine runs, the hybrid and EV models seem to only charge at widely separated intervals (probably to improve mpg or range).  I think this promotes battery plate sulphation, which accounts for the problem.

Until that happens, our only recourse is the CTEK.

Anecdote: 18 months ago, I bought a two year old KIA Soul EV, and, within weeks, I had a flat auxiliary battery, with SOH only 56%, so I replaced it (it was the KIA original) but kept it in the garage, and occasionally gave it a reconditioning charge.  The SOH has recovered to about 80%, so I'm pretty certain the battery was not the problem, but the charging regime was.

Thanks. I think I need to see how I get on but be prepared for the CTEK route. In the past 18 months I can go for a couple of weeks at a time without using the car and then only for a short trip or two. Then once every 5 to 8 weeks out on a long run.

[Roy124]

39 minutes ago, Nick72 said:

If they just put one in twice the size it probably wouldn't break the bank or make any difference to volume.

It's not paranoia.  The car was fine when new during the first lockdown and started perfectly normally after virtually no driving for 4 months.  Only after its first flat occurrence and an AA call-out did I start to learn the differences.  After the second flat I got advice on this forum; neither Toyota nor my garage 'reached out' to me. After the third occurrence I got a new Battery. 

As I said before, my garage installed a 52ah in lieu of the defective 45ah original. 

My usage has increased and I have not had to resort to the charger. 

[Nick72]

3 hours ago, Roy124 said:

It's not paranoia.  The car was fine when new during the first lockdown and started perfectly normally after virtually no driving for 4 months.  Only after its first flat occurrence and an AA call-out did I start to learn the differences.  After the second flat I got advice on this forum; neither Toyota nor my garage 'reached out' to me. After the third occurrence I got a new battery. 

As I said before, my garage installed a 52ah in lieu of the defective 45ah original. 

My usage has increased and I have not had to resort to the charger. 

I agree. Last thing I want is to be at 4.45AM mid winter to drive to the station for a 530am train to london on urgent business and the car doesn't start. That really isn't why I went with a Toyota. Quite the opposite.

[Grompix]

After a full CTEK trickle charge and a few days driving, my 12v auxiliary Battery in my Mk4 Yaris Hybrid is showing some strange readings again (see pic).  
The voltage when driving (or in 'READY' mode) initially shows a steady 14.2v then after a few minutes the voltage drops. At first it dropped to 13,7v but now it's shows 13.1v for the rest of a journey.
I'm unsure whether to take this as 'normal' behaviour for the car but I suspect it is further proof of a dodgy Battery (or something!).
Other than that observation, the car behaves OK. I'm watching closely to see in the voltage drops further.     

[Dala]

the problem is in the smart charging of the 12V car Battery while driving

I have a yaris 2020 hybrid and car Battery 35 Ah

the 12V car Battery is recharged 12.8 - 14.3V while driving

driving style and manner, outside temperature, distance traveled, route altitude profile and other factors affect this smart charging

12.6V and higher is a fully charged car battery at 100%

12.4V is 75%

12.2V is 50%

12.0V is 25%

11.9V is 15%

11.7% is 0% - fully discharged battery

I drive 100 km 3-5 times a week

12.7V in the evening

12.4-12.5V the next morning

if the car does not drive for 3 days - in the morning 12.1-12.2V

I have 4k cameras in front and back and a pandora smart PRO surveillance system

By deactivating the smart key, smart entry, welcome light, the battery discharge is reduced

a modern car must not stand in the garage

must drive regularly

when the vehicle is parked for 14-21 days, the car battery is completely discharged

[Roy124]

On 9/1/2021 at 1:51 PM, Nick72 said:

 

Dala, interesting figures that mirror my experience with my original Battery. 

[TonyHSD]

Hm, Interesting. When using the car in ready mode driving or standing still even with all consumables the 12v Battery supply power should not drop significantly from the 14.3v , if drops below perhaps may mean there is something wrong with the inverter., that was the old school measures to check the alternator if it’s working correctly or perhaps latest hybrids are somehow different. Once I checked my one 2010 hybrid and voltage after 4 days in cold winter around 0-5C° was 12.27v when I unlocked the car once I started it went up to 14.7v and stayed there even with all accessories on. , maybe dropped to 14.4v as far as I remember but not below that numbers. 

[Cyker]

It does seem like not all cars charge the same, esp. newer ones - Even my old Mk2 would not hold the voltage in the 14v once it detected the Battery was charged (I assume that's why anyway), but would drop to a lower charge or stop charging completely for a bit; Presumably to reduce the load on the engine to increase fuel efficiency.

Compare with my old D4D, which would be at 14.7v come hell or highwater while the engine was running  

I've noticed my Mk4 also doesn't keep the voltage constant - It'll often show something like 14.2-14.7 on start but quickly drop to 13 or even 12.something while I am driving, and constantly fluctuates up and down.

It may be an economy thing like in the Mk2, but could also be a better charging profile for the Battery type - AGM batteries should not be float-charged; They prefer cyclic charging or they start to off-gas.

Dala is right tho, these cars want to be driven, they don't like being left sitting for long periods. It's a good thing they're fun to drive!  

 

 

[Dala]

13 hours ago, TonyHSD said:

Hm, Interesting. When using the car in ready mode driving or standing still even with all consumables the 12v battery supply power should not drop significantly from the 14.3v , if drops below perhaps may mean there is something wrong with the inverter., that was the old school measures to check the alternator if it’s working correctly or perhaps latest hybrids are somehow different. Once I checked my one 2010 hybrid and voltage after 4 days in cold winter around 0-5C° was 12.27v when I unlocked the car once I started it went up to 14.7v and stayed there even with all accessories on. , maybe dropped to 14.4v as far as I remember but not below that numbers. 

"there is something wrong with the inverter" - may not be true 

Vehicle manufacturers are having to comply with increasingly stringent environmental regulations so are continually researching and employing clever technologies to lower fuel consumption and reduce emissions.  One of the technologies that has been around for several years, but which is now becoming standard on new vehicles, is  the 'smart' or 'intelligent' ECU-controlled alternator.

Smart alternators are essentially those that have their output voltage controlled externally via the Engine Control Unit (ECU) rather than by an internal voltage regulator as found on traditional alternators. 

In a non smart charge alternator, when the engine is running, the a constant voltage of between 13.8-14.4 volts is produced, depending on the Battery charge level and engine speed.

As smart alternators are ECU-controlled it enables manufacturers to vary the voltage output more than can be achieved with an internal regulator. This provides the opportunity to bring the voltage below 13.8V during periods when no further charging is required (e.g. when the Battery is nearly full) meaning that engine loads are reduced, fuel consumption is reduced and emissions are lowered, all helping manufacturers to comply with industry environmental regulations.

Regenerative braking is an energy recovery technology that takes the kinetic energy of the vehicle that is normally converted into wasted heat in the brake pads and discs during braking and instead converts it into electrical energy to re-charge the starter Battery. This is made possible because of the use of smart alternators that can be controlled by the ECU when deceleration is detected. During deceleration (for example when taking your foot off the accelerator) the ECU boosts the alternator voltage output as high as 15V+ to create a burst of charge into the battery. This high voltage puts an increased mechanical load on the engine, resulting in increased engine braking, meaning less of the kinetic energy is converted to wasted heat in the pads and discs. So the deceleration of the vehicle is putting charge back into the battery, saving fuel that would otherwise be required to re-charge it. This charge is then used to power the vehicle's electrical systems when the vehicle is accelerating or travelling at constant speed. During this time the alternator output voltage is reduced (to as low as around 12.5V), which reduces the load on the engine with a consequent reduction in emissions.

Regenerative braking is only effective if the starter battery has some spare storage capacity to absorb the charge created by the alternator during deceleration. If the starter battery was fully charged the electrical energy created would be wasted and so the ECU aims to maintain the battery at around 80% state of charge (low enough to have spare storage capacity but high enough to guarantee engine starting if required).

My hybrid has no alternator or starter and charges intelligently - see attachments ( please ignore fuel level - cannot be paired with new Toyota cars )

In the case of other additional electrical equipment in the car (like I have), it is possible to discharge the car battery in a week when the car not in motion. 

I talked to car battery dealers. During the Covid lockdown, they sold many more car batteries.

Smart charging kills car batteries when the car is not in motion.

 

[TonyHSD]

42 minutes ago, Dala said:

"there is something wrong with the inverter" - may not be true 

Vehicle manufacturers are having to comply with increasingly stringent environmental regulations so are continually researching and employing clever technologies to lower fuel consumption and reduce emissions.  One of the technologies that has been around for several years, but which is now becoming standard on new vehicles, is  the 'smart' or 'intelligent' ECU-controlled alternator.

Smart alternators are essentially those that have their output voltage controlled externally via the Engine Control Unit (ECU) rather than by an internal voltage regulator as found on traditional alternators. 

In a non smart charge alternator, when the engine is running, the a constant voltage of between 13.8-14.4 volts is produced, depending on the battery charge level and engine speed.

As smart alternators are ECU-controlled it enables manufacturers to vary the voltage output more than can be achieved with an internal regulator. This provides the opportunity to bring the voltage below 13.8V during periods when no further charging is required (e.g. when the battery is nearly full) meaning that engine loads are reduced, fuel consumption is reduced and emissions are lowered, all helping manufacturers to comply with industry environmental regulations.

Regenerative braking is an energy recovery technology that takes the kinetic energy of the vehicle that is normally converted into wasted heat in the brake pads and discs during braking and instead converts it into electrical energy to re-charge the starter battery. This is made possible because of the use of smart alternators that can be controlled by the ECU when deceleration is detected. During deceleration (for example when taking your foot off the accelerator) the ECU boosts the alternator voltage output as high as 15V+ to create a burst of charge into the battery. This high voltage puts an increased mechanical load on the engine, resulting in increased engine braking, meaning less of the kinetic energy is converted to wasted heat in the pads and discs. So the deceleration of the vehicle is putting charge back into the battery, saving fuel that would otherwise be required to re-charge it. This charge is then used to power the vehicle's electrical systems when the vehicle is accelerating or travelling at constant speed. During this time the alternator output voltage is reduced (to as low as around 12.5V), which reduces the load on the engine with a consequent reduction in emissions.

Regenerative braking is only effective if the starter battery has some spare storage capacity to absorb the charge created by the alternator during deceleration. If the starter battery was fully charged the electrical energy created would be wasted and so the ECU aims to maintain the battery at around 80% state of charge (low enough to have spare storage capacity but high enough to guarantee engine starting if required).

My hybrid has no alternator or starter and charges intelligently - see attachment ( please ignore fuel level - cannot be paired with new Toyota cars )

In the case of other additional electrical equipment in the car (like I have), it is possible to discharge the car battery in a week when the car is not running. 

I talked to car battery dealers. During the Covid lockdown, they sold many more car batteries.

Smart charging kills car batteries when the car is not in motion.

 

Thanks for the information, it seems technology goes ahead at faster pace, it does make sense those smart charging but then there is something not so smart if many end up with flat batteries on new cars, some even died before been sold., before the cars weren’t that smart and the batteries lasted ages👍

[Yugguy1970]

Yes, even the Battery in my none hybrid 2019 Focus would only charge to 80%.

[Grompix]

On 9/3/2021 at 9:00 PM, Dala said:

the problem is in the smart charging of the 12V car battery while drivingI have a yaris 2020 hybrid and car battery 35 Ah
the 12V car battery is recharged 12.8 - 14.3V while driving

 

On 9/1/2021 at 5:27 PM, Nick72 said:

I agree. Last thing I want is to be at 4.45AM mid winter to drive to the station for a 530am train to london on urgent business and the car doesn't start. That really isn't why I went with a Toyota. Quite the opposite.

 

18 hours ago, Cyker said:

It does seem like not all cars charge the same, esp. newer ones - Even my old Mk2 would not hold the voltage in the 14v once it detected the battery was charged (I assume that's why anyway), but would drop to a lower charge or stop charging completely for a bit; Presumably to reduce the load on the engine to increase fuel efficiency.

Compare with my old D4D, which would be at 14.7v come hell or highwater while the engine was running  

I've noticed my Mk4 also doesn't keep the voltage constant - It'll often show something like 14.2-14.7 on start but quickly drop to 13 or even 12.something while I am driving, and constantly fluctuates up and down.

 

9 hours ago, TonyHSD said:

Thanks for the information, it seems technology goes ahead at faster pace, it does make sense those smart charging but then there is something not so smart if many end up with flat batteries on new cars, some even died before been sold., before the cars weren’t that smart and the batteries lasted ages👍

Many thanks for taking the time and trouble to air your opinions / experiences here chaps. All very interesting (and useful).
My Yaris is still dropping from 14.2v to 13.1 v when in 'READY' mode or driving. I'm waiting to see if it drops further.
If it does not then it might point to the effect of 'smart' charging rather than a defective Battery.
I am tempted to replace my 12v auxiliary Battery with a higher AH one though (as Roy124 has). Anyone know the Toyota part number for such a Battery?