12v battery maintenance, issues, etc.

[ernieb]

With the PHEV and a charged traction Battery the moment the car is in READY mode the 375v to 12v Battery inverter is operational. You can hear it whine is you listen carefully, if you have a 12v accessory voltmeter you should see that the  battery is receiving a charge. I think this is true even if the traction Battery is at the zero user EV level i.e., 30%.

[philip42h]

24 minutes ago, TonyFR said:

Thanks for the reply. Maybe my trying to input the destination address when not in Ready mode did the dastardly deed, but nothing else I am aware of!

One more question: you write "As long as the auxiliary battery is healthy, and the car is used reasonably regularly, there is no issue with this system at all. Toyota guidance is that 60 minutes in Ready mode per week is sufficient". Well, I use the car almost every day, in EV mode when charged as it usually is. Does the reference to "60 minutes in Ready mode per week" refer to being stationery and letting the traction battery charge the 12v battery, or does it mean, you need to drive the car at least 60 mins per week, when by definition it is Ready? That's a dumb question perhaps, but I need to be clear.

You just need to be in Ready mode - it doesn't matter whether the car is being actively driven or not.

If you are using the car for, say, 10 minutes every day there should be no issue at all ...

... and in this case it really makes no difference whether the car is a PHEV or a HEV.

[Nick72]

15 hours ago, TonyFR said:

I know there have been other posts concerning the 12 volt battery but here’s another as I consider this item to be the achilles heel of an otherwise excellent car.
My car had its first annual service on 8 September and on the 11th we drove 700km to a Spanish destination. Obviously in HV most of the time. Left it for three days (the first night of which the front windows were accidentally left open but discovered and rectified in the morning - would the 12v battery have been affected by this?). No problem then driving it to next destination about 50km away. Three days later the car (unused again for three days) died on me shortly after I tried to put a new address into nav system - without having put the car into Ready, I should add. Car completely dead. Won’t mention all the pain involved but eventually the breakdown guy arrived and jump started it from under the bonnet (which I admit I didn’t know could be done, thinking he would have to go to boot for 12v battery - but have since learned a bit more by properly studying the manual.) I then drove to the nearest Toyota dealer who recharged the 12v battery, stating it had been too low.
On the way home we got stuck in a monstrous traffic jam in the late evening on the A43 near Grenoble, and hardly moved for an hour, but with lights on, worried that the car might die as the traction battery was at what I call the Hybrid setting (30% ?), and the ICE wouldn’t run, being mostly stationary, unless I  put it onto the Charge setting. Fortunately we managed to get off the motorway and get home safely.
Questions:
1  is there a simple way to monitor the 12v battery health? On the US forum some people suggest a simple voltmeter to plug into the 12v socket (aka cigar lighter!). Would this give a useful reading?
2  what parts of the car are directly powered by the 12v battery once we are under way? Could the lights have failed in an enforced nighttime stoppage? Or would the ICE kick in to charge the traction battery to then trickle charge the 12v battery? Dare we use the heaters or AC in that sort of situation? (We didn't)
3  More generally, if, as in my case, most car trips are around town and solely in EV, should we routinely charge the 12v battery by (as I understand) leaving the car in Ready for 20 minutes to let the traction battery charge the 12v battery? If so, how often? Or does the act of charging the traction battery do that sufficiently anyway? There seems to be some ambivalence in the posts I have read on the forums.

I find the lack of any warnings concerning 12 v battery on the dashboard to be a real negative!  Sorry to go on about this but my faith in the car has been shaken.

 

Sorry to hear this Tony. I was having flashbacks to my Peugeot 3008 GT 300 hybrid 4 PHEV as I read it. That was permanently chronic.

Just thoughts ahead...

I've not had any 12V issues other than a brief weird event I mentioned here which may have had a 12V origin (loss of power and weird message). 

Sometimes I don't use the car for over a week and then only take it to the shops 5 minutes round trip away once or twice in a week. That can go on for weeks before I go on a long business drive of several hundred miles round trip. I've been overseas having hardly used the car previously and for over 2 weeks. No problems at all.

So I'm wondering if this variance in experience of the 12V Battery is related to...

1. As Ernie says, a dodgy connection somewhere and which could include a very low level short. Like a leakage current.

2. Things plugged in like accessories. I don't leave anything plugged in. No Dashcam (though I'm tempted to get one), no cigarette lighter, etc. Oh, yes, one thing I do leave plugged in is a 3 pin power adaptor plug, plugged into the boot euro socket. 

3. Whether you leave the car plugged into the Wall Box. Even though I may not use the car for a while and then rarely use it, I tend to leave it plugged into the 7.4kW wall box a lot. I can't recall what the verdict on this was but I'd be very surprised if the 12V Battery wasn't being trickle charged off the traction Battery when plugged in. Preconditioning runs off the Wall Box without wasting any traction battery charge so I'm wondering.

4. How much you use the App to wake the car up, when you do the refresh thing. I think there's a warning somewhere in the App about this.

Phillips advice all good but I've not stuck to some of it and had no problems. I did buy a good battery booster which I keep in the centre arm rest just in case. I probably need to charge that again. 

I wonder if I'm getting away with it from the once a month long business blast.

 

 

[nlee]

5 hours ago, Nick72 said:

Whether you leave the car plugged into the Wall Box. Even though I may not use the car for a while and then rarely use it, I tend to leave it plugged into the 7.4kW wall box a lot. I can't recall what the verdict on this was but I'd be very surprised if the 12V battery wasn't being trickle charged off the traction battery when plugged in. Preconditioning runs off the Wall Box without wasting any traction battery charge so I'm wondering.

I posted about this some time ago. The verdict I came to from the various sources is that the 12v Battery is only getting charge when plugged in when the Battery heating/cooling is running. So only when the traction Battery is charging but not if the cooling/heating isn't called for. I'd make a guess that you are right that it will charge during pre-conditioning as well.

[nlee]

I've not had any actual problems with the 12v Battery but I've had a AA Car Genie from a previous car attached to the OBD port and observed some weird results. 

The device (which has similar functions to MyT) sends a notification and text if the Battery goes low. Below 11.5V, I think. It happens regularly but I presume the way the car works, i.e. it's not turning a starter motor, it doesn't need 11.5V to power up the electronics. 

What is interesting is that I usually get a notification if the car has not been used for 2 to 3 days. However, when I've done longer runs recently, I get the notification in the early hours of the following morning, which is counter intuitive.

I've taken it out now because the device itself will be drawing it's own current continuously, albeit very small I'd have thought.

[ernieb]

I decided to check mine this morning and include 2 images.

first ACC mode voltage 11.7v

Second READY mode voltage 14.3v (immediately on going into READY mode)

The 11.7v seems low as we did a 115 miles run a few days ago and then used every day, a few 10 - 15 mile trips.

 

[ernieb]

….. I should have said that the car was charged over night and I’d just disconnected the charge cable when I took these photos. 

[nlee]

37 minutes ago, ernieb said:

….. I should have said that the car was charged over night and I’d just disconnected the charge cable when I took these photos. 

Thanks Ernie. Would be good to see what it is, say 10 mins, after a decent trip in ACC, then maybe the following morning? To see how the voltage decreases over a period of time.

I might get something like this myself, rather than faffing with the multimeter.

[philip42h]

I thought that I'd have a bit of a faff with the multi-meter - measured at the jump-start point under the bonnet I get:

• 12.0v with the system Off
• 11.8v with the system in Accessory mode - amongst other things, the dash cam fires up in Accessory mode
• 11.5v with the system in Ignition On mode - the car is in the garage and the headlights come on automatically with Ignition On
• 14.5v with the system in Ready mode

The car had been on a good long trip a week or so ago. Since then it has been on a handful of local potters and otherwise been sat idle in the garage - so a fairly normal state for me.

This doesn't tell us much other than with the car Off my Battery delivers it's nominal voltage and that there is a drain in Accessory mode and Ignition On mode that pulls down the voltage but not (in my case) so much as to prevent the car going into Ready mode. It's probably worth noting that under normal circumstances we would go straight from Off to Ready mode.

[Roy124]

What charger did you use Ernie, once charged my CTEK goes to a float cycle at a stated 13.6 followed by pulse at 12.7 to 13.7.

On the tin that is 🙂

 

[philip42h]

2 minutes ago, Roy124 said:

What charger did you use Ernie

Ernie would have used a 7.4kW wall charger or the granny cable - he's talking about charging the traction Battery in the PHEV rather than the 12v auxiliary Battery ... 😉

[philip42h]

On 9/25/2022 at 10:47 AM, TonyFR said:

Three days later the car (unused again for three days) died on me shortly after I tried to put a new address into nav system - without having put the car into Ready, I should add. Car completely dead.

So, going back to the OP's problem ... it  shouldn't be a problem to put the car into Accessory mode for 30 seconds in order to set "tomorrow's destination" - I do this every now and again - but you do then need to press the Start button twice to cycle through Ignition On and back to Off. It would be better to go into Ready mode for this operation to at least give the auxiliary Battery the opportunity to gain charge rather than simply use it.

[nlee]

10 minutes ago, philip42h said:

I thought that I'd have a bit of a faff with the multi-meter - measured at the jump-start point under the bonnet I get:

• 12.0v with the system Off
• 11.8v with the system in Accessory mode - amongst other things, the dash cam fires up in Accessory mode
• 11.5v with the system in Ignition On mode - the car is in the garage and the headlights come on automatically with Ignition On
• 14.5v with the system in Ready mode

The car had been on a good long trip a week or so ago. Since then it has been on a handful of local potters and otherwise been sat idle in the garage - so a fairly normal state for me.

This doesn't tell us much other than with the car Off my battery delivers it's nominal voltage and that there is a drain in Accessory mode and Ignition On mode that pulls down the voltage but not (in my case) so much as to prevent the car going into Ready mode. It's probably worth noting that under normal circumstances we would go straight from Off to Ready mode.

Ernie has got us all reaching for the multimeter and rushing about to the car 😀

I've just done the same but used the cigar lighter, rather than the jump start points, so don't have a system off value but the others are similar.

ACC - 11.7V

IGN - 11.5V

READY - 14.4V

I did 2x 1 hour trips yesterday using a EV for the first trip and HEV for most of the return trip.

[ernieb]

12 minutes ago, Roy124 said:

What charger did you use Ernie, once charged my CTEK goes to a float cycle at a stated 13.6 followed by pulse at 12.7 to 13.7.

On the tin that is 🙂

 

Philip is more or less correct, I used a granny cable rather than 7.4kW charger.

the CTEK chargers are good and I might invest in one myself for the winter to trickle charge the Battery.. I do have a Lithium Ion booster in the car which I had on a previous car so will easily start a 2lt ICE but doesn’t need to be that big to boost a HEV/PHEV.

[ernieb]

2 minutes ago, nlee said:

Ernie has got us all reaching for the multimeter and rushing about to the car 😀

I've just done the same but used the cigar lighter, rather than the jump start points, so don't have a system off value but the others are similar.

ACC - 11.7V

IGN - 11.5V

READY - 14.4V

I did 2x 1 hour trips yesterday using a EV for the first trip and HEV for most of the return trip.

So similar to mine and I’ve been out a rechecked with an old but very serviceable AVO MK 10, pretty well the same as the little, cheap. LED voltmeter.

[TonyHSD]

Using the car every day 10 min each time it’s not sufficient to recharge properly 12v Battery. Normal daily use will suggest 30 min plus each time the car has been started. If that is not possible best to have solar charger or smart charger available and connect to the car when car is not in use to top up and maintain the Battery.
 

There are few tips and tricks how to preserve 12v Battery some been mentioned already like avoid keeping the car in acc mode one or two presses on start button, keep the car off or in ready mode. Turn off all automatic functions like interior lights coming on when you turn off the car or when walking around the car, you may need to do that with obd adapter like Carista., The side mirrors to automatic fold, home lights if you have any set, pretty much all auto functions, wipers, lights. 
Remember, the biggest 12v battery draw comes from your electric brake booster, this activates when opening and closing drivers door., try not to use unnecessary., forgot something inside, unlock the car and take it from the passenger door instead. 60 min ready mode is for winter time if you don’t drive the car lockdown or similar. Anything over 20-30 min each time should be fine. Car phone charger with voltage meter is a good idea too, Amazon plenty of them. 

[philip42h]

2 hours ago, TonyHSD said:

Using the car every day 10 min each time it’s not sufficient to recharge properly 12v battery.

What is your basis for this statement?

All we require to do is top-up the 12v auxiliary Battery to replace the charge drawn via "parasitic drain" while it has been parked up since it was last used. Whether that is 10 minutes in Ready mode since it was last used yesterday or 60 minutes in Ready mode since it was last used last week doesn't make any material difference. The number of starts doesn't make any material difference either since there is very little power required from the 12v auxiliary Battery to start the car.

Less frequent longer runs may well be better for the car overall, but frequent short trips are just fine when it comes to keeping the 12v topped-up. 😉

[TonyHSD]

1 minute ago, philip42h said:

What is your basis for this statement?

All we require to do is top-up the 12v auxiliary battery to replace the charge drawn via "parasitic drain" while it has been parked up since it was last used. Whether that is 10 minutes in Ready mode since it was last used yesterday or 60 minutes in Ready mode since it was last used last week doesn't make any material difference. The number of starts doesn't make any material difference either since there is very little power required from the 12v auxiliary battery to start the car.

Less frequent longer runs may well be better for the car overall, but frequent short trips are just fine when it comes to keeping the 12v topped-up. 😉

Hi, 

similar to ice cars frequent start and stop of the engine (hybrid system) requires a lot more 12v power than everyone might think . The reason is the electric brake booster, the diagnostics that happens in all ecu ‘s, I have 21 in my 2010 hybrid and you may well have another 10 on top. 👍 Every time you unlock the car and open drivers door or close it the brake booster pressurises itself and de pressurises afterwards, same happens if you stay in the car , car is off but you decided to open your window or fold the mirrors for example, you will set the car in acc mode and again brake booster will do these process again. If your interior lights are on while the booster is working you can even notice how the lights dim, at least if they are standard bulb filament, if they are led I don’t know, people with led lights can check and share. That is my theory based on tests and monitoring the systems of the car while been using it. 👍 Taxis for example almost never has issues with flat Battery or rusty brakes, two common problems on most hev, phev and bev. , the reason is because these cars stay ON for long, sometimes for hours. My car also an example, 12 years old with original batteries. , I use for work and spent 12 hrs a day in, sometimes more and I do travel 200+ miles on daily basis. , the car remains in ready mode for hours. 😉🔋

[IanML]

My old Toyota doesn't get a lot of use, but it is parked outside, and I have a Halfords Solar Panel charger placed on the dash and plugged into the OBD2 connector.

Always starts first flick of the key, even after a month.

[FROSTYBALLS]

Similar topics merged.

[roadster-rav]

On 9/26/2022 at 12:01 PM, nlee said:

Ernie has got us all reaching for the multimeter and rushing about to the car 😀

I've just done the same but used the cigar lighter, rather than the jump start points, so don't have a system off value but the others are similar.

ACC - 11.7V

IGN - 11.5V

READY - 14.4V

I did 2x 1 hour trips yesterday using a EV for the first trip and HEV for most of the return trip.

These readings are worryingly low for a decent Battery. I don't know exactly which accessories were active but I would expect a properly maintained Battery to be able to sustain at least 12.1 volts for a significant period of time under a typical load (say 2 to 4 amps). Surely there is more to this than meets the eye? For example voltage drop between testing point and Battery location.

[philip42h]

32 minutes ago, roadster-rav said:

These readings are worryingly low for a decent battery. I don't know exactly which accessories were active but I would expect a properly maintained battery to be able to sustain at least 12.1 volts for a significant period of time under a typical load (say 2 to 4 amps). Surely there is more to this than meets the eye? For example voltage drop between testing point and battery location.

What folk are demonstrating is that these readings are perfectly normal for a RAV4 hybrid. The auxiliary Battery sits happily at 12v under the types of load that it is designed to support with the car switched Off. Under "a typical load (say 2 to 4 amps)" it sits at around 14.5v while being supported by / charged from the traction Battery. There's nothing to worry about here at all ... 😉

[nlee]

Agree, this does seem low but have never had any issue starting the car so I suspect it doesn't need much to fire up the electronics to get the car into ready. Until it causes a problem, I'm not overly concerned but I'd be very concerned with these voltages if I had a car that needed to crank the starter motor.

I got one of the gizmos similar to Ernie (incidentally with quick charge ports, one USB-A and one USB-C, which are much better than the inbuilt ports for fast charging). I checked it against the multimeter readings and it was spot on. Yesterday morning I checked it in accessory and it was reading 11.6v. I decided to dig out the Ctek and give the Battery a full charge through the day. I took it off charge last night after about 9 hours and when I checked (in accessory again) this morning, it was still only reading 12.1v. I wasn't charging the traction Battery last night. This still seems much lower than I expect. I always thought a voltage like that in a standard lead Battery was about 20% charge.

[ernieb]

17 minutes ago, nlee said:

Agree, this does seem low but have never had any issue starting the car so I suspect it doesn't need much to fire up the electronics to get the car into ready. Until it causes a problem, I'm not overly concerned but I'd be very concerned with these voltages if I had a car that needed to crank the starter motor.

I got one of the gizmos similar to Ernie (incidentally with quick charge ports, one USB-A and one USB-C, which are much better than the inbuilt ports for fast charging). I checked it against the multimeter readings and it was spot on. Yesterday morning I checked it in accessory and it was reading 11.6v. I decided to dig out the Ctek and give the battery a full charge through the day. I took it off charge last night after about 9 hours and when I checked (in accessory again) this morning, it was still only reading 12.1v. I wasn't charging the traction battery last night. This still seems much lower than I expect. I always thought a voltage like that in a standard lead battery was about 20% charge.

I tend to agree it does seem low but as you’ve said the car starts OK even with the lower than might have been expected number. However, it seems to be consistent with what others are measuring so must assume it’s OK. I’ve just purchased a NOCO charger and will use this when it’s colder or if I’m not likely to use the car. I also got the cable with the  eyelets and socket to attach to the 12v Battery so will try to rig that up over the next day or so,

[nlee]

32 minutes ago, ernieb said:

I tend to agree it does seem low but as you’ve said the car starts OK even with the lower than might have been expected number. However, it seems to be consistent with what others are measuring so must assume it’s OK. I’ve just purchased a NOCO charger and will use this when it’s colder or if I’m not likely to use the car. I also got the cable with the  eyelets and socket to attach to the 12v battery so will try to rig that up over the next day or so,

I've ordered the lead for my Ctek charger yesterday because I now realise I left the original one attached to my old car. Doh!