12v Battery life in Accessory Mode

[Greybeard]

I have had my Yaris hybrid for a couple of weeks now.  When switched to Accessory Mode (ie one push of the start button) we listened to the radio for 15 minutes with nothing else switched on. After 15 minutes I got a "Battery Low" warning. I know from a previous experience that if I ignore it the car will shut down, won't lock, won't start, won't do anything until the Battery is charged so I immediately switched off.  Spoke to the dealer today who firstly tried to tell me this was normal, than asked what Accessory Mode was which made me quite cross!  Surely the car's 12v Battery should be capable of powering the radio for more than 15 minutes?  If not, it's hardly fit for purpose.  Could anyone tell me if 15 minutes is normal or would you expect to be able to listen to the radio without the engine running for at least several hours. What is your experience please?

[TonyHSD]

33 minutes ago, Greybeard said:

I have had my Yaris hybrid for a couple of weeks now.  When switched to Accessory Mode (ie one push of the start button) we listened to the radio for 15 minutes with nothing else switched on. After 15 minutes I got a "Battery Low" warning. I know from a previous experience that if I ignore it the car will shut down, won't lock, won't start, won't do anything until the battery is charged so I immediately switched off.  Spoke to the dealer today who firstly tried to tell me this was normal, than asked what Accessory Mode was which made me quite cross!  Surely the car's 12v battery should be capable of powering the radio for more than 15 minutes?  If not, it's hardly fit for purpose.  Could anyone tell me if 15 minutes is normal or would you expect to be able to listen to the radio without the engine running for at least several hours. What is your experience please?

Hi, 

what you have done is wrong and absolutely not recommended to keep the car in accessories mode for any reason other than some sort of maintenance purposes. 
Toyota hybrids should always be kept in ready mode when seating in and using my electric accessories. 
Regards 

[Greybeard]

10 minutes ago, TonyHSD said:

Hi, 

what you have done is wrong and absolutely not recommended to keep the car in accessories mode for any reason other than some sort of maintenance purposes. 
Toyota hybrids should always be kept in ready mode when seating in and using my electric accessories. 
Regards 

Thanks Tony. That's very interesting.  The handbook says "In Accessory mode some electrical components such as the audio system can be used.  ACCESSORY will be displayed on the multi-information display".  While I definitely am not doubting your word, this indicates that it's ok to use "Accessory" to listen to the radio, so I'm confused!

[MikeSh]

54 minutes ago, Greybeard said:

Surely the car's 12v battery should be capable of powering the radio for more than 15 minutes?

But it's not just the radio. There's a bunch of little computers and stuff being powered, and modern radio/head units are quite power hungry with their large screen and powerful sound systems.

 

4 minutes ago, Greybeard said:

The handbook says "In Accessory mode some electrical components such as the audio system can be used.

And you can. Just not for very long.

As Tony says, keep it in Ready mode. If the main Battery gets low the engine will start and run for a few minutes, but that's the way it is.

[Roy124]

Did it actually say Battery Low or to preserve the Battery?  I agree with Tony though, before I knew better, waiting for my wife at the dentist I had the motors off and radio on, as per an ICE.  It would switch off as you say. 

If you leave it in Ready mode you can, if you want, switch on aircon or operated the windows.  The power management system will operate to meet your requirements. 

Switching off lights, wipers, aircon, fan, heated seats etc will reduce your demands and the system WILL run the ICE less frequently while keeping the 12v Battery charged. 

 

 

[TonyHSD]

The idea of keeping the car in ready mode always and for as long as you can is not only to preserve the life of the 12v Battery but also to recharge it and keep it in top condition. Hybrids and electric cars use small 12v batteries to supply electricity to all auxiliary system of the car except traction motors and AC. Since they does not turn the crankshaft to start the engine they does not require to be powerful and heavy but been small and light comes with a trade off and this is the fact they are not suitable for use as an accessories power source unless the car is in ready mode where electricity will come off the main hybrid Battery which when low will be charged by the engine that works as generator.
Best practice to have healthy 12v Battery is to keep the car in ready mode for anything and as long as you can. 👍

[flash22]

15 min cut off in accessory mode it to protect the Battery - low Battery is just a shock warning in those circumstances - Naughty boy don't do it again type thing 😁

[Derek.w]

58 minutes ago, TonyHSD said:

Hi, 

what you have done is wrong and absolutely not recommended to keep the car in accessories mode for any reason other than some sort of maintenance purposes. 
Toyota hybrids should always be kept in ready mode when seating in and using my electric accessories. 
Regards 

Thats normal but you still  have Battery power left to start the vehicle.

Next time I am leaving my solar panel in the window while I wait 

I have also seen a setting for turning off the display screen I not sure what memory location it was in possibly settings.

[Mooly]

1 hour ago, Greybeard said:

Surely the car's 12v battery should be capable of powering the radio for more than 15 minutes?  If not, it's hardly fit for purpose.  Could anyone tell me if 15 minutes is normal or would you expect to be able to listen to the radio without the engine running for at least several hours.

This isn't going to sound very helpful (sorry) but all these myriad complaints over the 12 volt batteries ending up flat show a staggering lack of competence in the design of all these vehicles. 

Toyota are supposed to be world leaders and yet the forums are awash with folk having these problems, using solar powered chargers to try and ward off failure, constant worry over whether it will start or not. What the actual problem is I don't know, for example is it simply to high a background current draw and/or things not going to sleep when they should and waking up and causing excess power drain. Something is going on though.

This is absolutely crazy in this day and age and with what are supposed to be state of the art vehicles.

As to the question on the radio... a power hungry entertainment set up if it pulled a couple of amps as an average should work fine for 12+ hours leaving the Battery around 30 to 40% charged after that time. And therein lies a problem. It takes a long time to recharge back to 100%, I would think several hours before the charge current has fully tapered off. In less extreme use and if the Battery gets a little discharged and doesn't then have enough running time to replenish then it becomes an insidious downward SOC (state of charge). 99% one day to say 95%. A few minutes running and its back to 97%. The the same happens again and you are now at say 90%. You drive for 10 minutes and its back up to 96%. So day on day it is getting an ever lower SOC.

This seems to be what is happening based on the numerous complaints I read here and the actions people take to mitigate them.

[Greybeard]

Well, thank you guys, I stand corrected🙂. Why couldn't the handbook have told me that? Life would have been so much simpler! I also agree with everything Mr Mooly says.

[Derek.w]

For my situation car needs to travel at least 5000 or 6000 miles a year and this I do not do.

On top of this I do a lot af short jurneys and this is no help.

A alternator can recharge faster than a DC to DC converter.

[Roy124]

Molly, not just Toyota.  Check other user forums. 

Now I believe Kia eNiro has a switch that allows the hybrid to recharge a flat 12v Battery without using jumpers. 

Obviously that hybrid needs to have sufficient capacity too. 

A larger Battery might make a difference but would affect the car weight etc etc. 

Worry not, current Hybrids are a passing phase. 

[FROSTYBALLS]

Our non-hybrid Hyundai i20 also has a warning come up if the multimedia/sat nav unit is used without the engine running. After 15 minutes, power to the unit is cut off to prevent the Battery losing too much charge.

So not just Toyotas which have  Battery warnings in these sorts of circumstances. 

[Cyker]

My Fiesta and previous non-hybrid Yarisuesises would also warn and cut off the radio if run off position 1 (ACC) for 15-30 minutes IIRC.

2 hours ago, Greybeard said:

Thanks Tony. That's very interesting.  The handbook says "In Accessory mode some electrical components such as the audio system can be used.  ACCESSORY will be displayed on the multi-information display".  While I definitely am not doubting your word, this indicates that it's ok to use "Accessory" to listen to the radio, so I'm confused!

It really means you *can* use the radio in ACC mode, not that you *should*. Having the car fully on (Key Position 2 or 'Ready mode') is just the best mode to be in whenever anything on the car is to be used.

TBH I don't know why ACC is a thing on EVs and hybrids - It makes sense on normal cars as you don't want to be running the engine continuously when listening to the radio waiting for your SO/friend/little terrors to come back, but it's pointless on EVs and hybrids. Then again I feel the same way about the idle creep fighting against the parking/handbrake...!

 

[Mooly]

1 hour ago, Derek.w said:

For my situation car needs to travel at least 5000 or 6000 miles a year and this I do not do.

On top of this I do a lot af short jurneys and this is no help.

A alternator can recharge faster than a DC to DC converter.

A 20yr old Corolla that belonged to my father sits on the drive. Some years ago it did as little as 500 miles in the year, it would sit for 2 to 3 weeks in the depths of winter and when it was used it did a mile here and a mile or so there... and never a problem with Battery charge. That low usage level occurred for a few consecutive years. And its still going strong and had a good motorway run this morning. Amazing, and it just drives so well. It pulls like a train.

The output of a modern alternator is in the 70A and above region (won't be quite that when idling but still plenty) and that can really bring the charge level back quickly on a healthy Battery but ultimately the Battery is what determines how much current flows as the charge increases. The current tapers off over time.

 

52 minutes ago, Roy124 said:

Molly, not just Toyota.  Check other user forums. 

Thanks. I remember reading about the Kia, well it getting mentioned anyway on this site some time ago. It might even have been yourself.

 

52 minutes ago, Roy124 said:

A larger battery might make a difference but would affect the car weight etc etc. 

Well it might in some circumstances... but if the problem is that charge out of the battery is more than charge going in... and that is what must be happening now... then a larger battery won't fix that.

What it will allow is a longer time from fully charged to a problem occurring. That might benefit someone who can normally keep the battery close to fully charged and then who occasionally does have to leave the vehicle for an extended period. 

52 minutes ago, Roy124 said:

Worry not, current Hybrids are a passing phase. 

Ultimately yes. 

[Derek.w]

Small Hybrid Battery recomended charge is 2 amps so this is what I expect from DC to DC converter.

New cars have a lot of computers pulling Battery down like looking for keys signals.

Thats one Battery drainage not on old cars & computers that sleep still use some electric!.

[Derek.w]

1 hour ago, FROSTYBALLS said:

Our non-hybrid Hyundai i20 also has a warning come up if the multimedia/sat nav unit is used without the engine running. After 15 minutes, power to the unit is cut off to prevent the battery losing too much charge.

So not just Toyotas which have  battery warnings in these sorts of circumstances. 

I believe it uses the same Battery type as the Yaris Hybrid but has a starter motor.

Please Note Yaris Hybrid depending on year Battery poles are reversed.

[MikeSh]

1 hour ago, Mooly said:

A 20yr old Corolla that belonged to my father sits on the drive. 

Yes, but back then car makers didn't give a ***** about the environment and there were few regulations.

Nowadays there are any number of reasons to save weight, reduce use of many chemicals, etc.

Stream engines were great ... in their day. We are somewhere different now.

[Derek.w]

You can always try just turning accesory mode on again and running it until it stops working then try starting car but you need to be at home so you can charge it incase it fails to start.

But then again why risk it especilly in the winter, just have a alteritive means to recharge the Battery.

I have two alternative for charging solar and mains Battery charging options.

[Cyker]

The hybrids are at a disadvantage as they have constant-current  chargers, the Battery is smaller, and they have a lot more always-on systems then a lot of other cars.

Disabling keyless entry will extend the Battery life considerably when the car isn't going to be in use, and driving it regularly will keep the Battery charged enough that when it isn't going to be used it won't drain so fast.

[TonyHSD]

Turning the car ON and OFF, unnecessary opening of drivers door, and pressing start button twice and then off again., these events activates the electric brake booster that pressurises and depressurises itself and when this is happening the 12v Battery is perhaps most loaded. Avoid those scenarios and keep the car in ready mode for as long as you can after each time you have started it. Example, you have your car parked but you remember that you forgot something inside and you made your way to the car, ok just unlock and use passenger door instead, take your stuff and close the door, lock and walk away. Minimum Battery power have been used, if you did that via drivers door as soon as you have opened the door the brake booster will come to live draining your Battery, then 15 seconds after you shut the door again battery drain as booster will depressurise .
Hope these simple tips can be of some help 👍

[Mooly]

8 hours ago, MikeSh said:

Yes, but back then car makers didn't give a ***** about the environment and there were few regulations.

True enough in itself but that is a different argument to the problem of batteries going flat... however I'd bet the environmental impact of keeping such a car as the old Corolla for 20yrs is more environmentally friendly than total lifetime costs of a modern hybrid or EV when the energy and resources needed to recycle the Battery packs and also the impact of extracting those materials in the first place are accounted for.

 

10 hours ago, Mooly said:

Worry not, current Hybrids are a passing phase. 

Quite timely... latest headlines in the papers today.

 

[IT Troll]

1 hour ago, Mooly said:

resources needed to recycle the battery packs

I don't think that is even possible yet. I believe the plan is to use them as a storage buffer at power stations for a bit, then once they are no longer useful, bury them.

[Roy124]

Is disabling keyless entry a sticky option or does it reset after switch off? 

Frosty mentioned automatic switch off on other makes too.   Depending on sophistication your accessory mode, ie switched off, may allow other options too. 

Yes, a much larger Battery will also drain eventually, but my 05 Merc had a huge stop/start capable Battery but not stop/start equipped.  It was fitted for but not with TV but could play DVD and run the heater fan using residual heat until it reached a safe discharge level. 

[MikeSh]

11 hours ago, TonyHSD said:

as soon as you have opened the door the brake booster will come to live draining your battery

This is true. I usually get in quickly, on the edge of the seat, press the brakes and then the start button or the car in ready mode while the booster is still running to minimise that drain. You can hear the booster speed up as the 12V supply kicks in.

11 hours ago, TonyHSD said:

then 15 seconds after you shut the door again battery drain as booster will depressurise

That's not true of my MK3. The booster only starts on entry if the car has been idle for hours. Often it just runs for a couple of seconds then, so I think it's just 'natural' leakage of the pressure. Certainly going back to the car a few minutes later doesn't make the booster run.

And why would the high pressure pump need to run to depressurise anyway?