PHEV Remote Aircon... which battery is used when?

[ernieb]

First get into the car as that needs 12v unless you use the mechanical key. So don’t leave anything in the boot. If the traction Battery is charged then you only need to put the car in the READY mode for awhile and that will top up the 12v Battery. 

[philip42h]

55 minutes ago, Nick72 said:

Thanks. I'll just need to make sure I take it for a drive once a week or I'll need to be charging the 12V battery which is a faff as that means taking it out to put it in the shed to charge it. Really feels like a backward step when my 17 or so old Corsa would start first time even after 6 weeks. 

Got me thinking. So, if the 12V battery is dead why exactly won't the car start? I mean it goes to EV mode first in any case and when it says ready the traction battery via inverter is charging the 12V battery? Or is it the case (oh god please don't agree) that the car electronics are all powered off the 12V battery and in which case a dead battery probably means a world of pain?

Your old Corsa was probably completely 'off' when the ignition was off so you had only to worry about leakage currents and short circuits. Welcome to the age of modern, and far more sophisticated, cars.

I don't know, but I would reasonably assume that all the normal car electrical system would be run off the 12V supply. Why on if you replaced earth would Toyota invent a whole new rang of systems when 12V ones are readily available off the shelf. So that's a 'yes' - sorry. The owners manual lists the things that you would need to reinitialise if you replaced the 12V Battery - so probably not a good idea to remove it from the car if you don't have to. But there's a world of difference between a Battery that's a bit run down and one that is completely missing in action.

33 minutes ago, ernieb said:

First get into the car as that needs 12v unless you use the mechanical key. So don’t leave anything in the boot. If the traction battery is charged then you only need to put the car in the READY mode for awhile and that will top up the 12v battery. 

So, as Ernie says, all you need to do is get the car into Ready mode.

But, and a really, really don't know for a fact but I believe it isn't quite as simple as that!

In order to get into Ready mode you need to put your foot on the brake and press the Start button. Why do you have to depress the brake pedal? And what happens when you do?

I believe that it is a safety interlock - you need to have working brakes, and the brake servo is an electric pump, running off the 12V system. So, you need to have enough oomph in the 12V Battery to apply the brakes before you can get into Ready mode.

You (we) need only a tiny 12V jump start pack to get over this hurdle ... 🙂 

[Thermal]

2 hours ago, Nick72 said:

So, if the 12V battery is dead why exactly won't the car start?

The 12V Battery is also used to initialize some of the car's computers and to close the "contacters" in the HV Battery to activate the hybrid system.

[Nick72]

3 hours ago, philip42h said:

Your old Corsa was probably completely 'off' when the ignition was off so you had only to worry about leakage currents and short circuits. Welcome to the age of modern, and far more sophisticated, cars.

I don't know, but I would reasonably assume that all the normal car electrical system would be run off the 12V supply. Why on if you replaced earth would Toyota invent a whole new rang of systems when 12V ones are readily available off the shelf. So that's a 'yes' - sorry. The owners manual lists the things that you would need to reinitialise if you replaced the 12V battery - so probably not a good idea to remove it from the car if you don't have to. But there's a world of difference between a battery that's a bit run down and one that is completely missing in action.

So, as Ernie says, all you need to do is get the car into Ready mode.

But, and a really, really don't know for a fact but I believe it isn't quite as simple as that!

In order to get into Ready mode you need to put your foot on the brake and press the Start button. Why do you have to depress the brake pedal? And what happens when you do?

I believe that it is a safety interlock - you need to have working brakes, and the brake servo is an electric pump, running off the 12V system. So, you need to have enough oomph in the 12V battery to apply the brakes before you can get into Ready mode.

You (we) need only a tiny 12V jump start pack to get over this hurdle ... 🙂 

Complicated I guess. Wished they just put a larger Battery in it then I wouldn't need to worry at all. 

I heard that putting it in Ready doesn't always mean the 12V Battery is being charged. That is also depends on current voltage?

[ernieb]

If you have a convenient mains supply then the trickle charge route is a probably the best option and some people have installed a connector so that they can just 'plug' in the charger. In fact some chargers come with the kit or it can be bought as an option. As I've said elsewhere I carry a Lithium Battery booster accessible from inside the car. (it's actually in the boot but I have a boot box with a pouch that i can access from inside the car by lowering the rear seat). It's powerful enough to start a normal car if required and I've been a good samaritan to a number of neighbours since I bought it, better than the 12v standard Battery I used to have by miles.

[Yugguy1970]

I would imagine that sitting in Ready will charge the 12V to what it deems as sufficient capacity, which is likely not 100%.

Toyota's own advice during periods of long inactivity is to run in Ready for an hour which would imply that it also keeps the 12V in the right condition.

I can't even locate the 12V in my HEV.  Where is it?

[ernieb]

On the PHEV it’s on the RH side of the boot, lift the boot floor there is a covered space in the rear wing and the cover can be pulled off to show the Battery. Assume it’s in a similar place?

[philip42h]

According to the handbook: "The 12-volt Battery is located in the right-hand side of luggage compartment." So, it's in the boot, behind / beneath the trim. I believe my car must have one but I've never seen it! 😉

There is an "exclusive jump starting terminal" within the fuse box, under the bonnet - which is more easily accessible. I use this to trickle charge the Battery if/when lockdown etc. has prevented normal use of the car.

When in Ready mode, the DC/DC Converter steps down the high voltage from the traction Battery (244.8V in the HEV, 355.2V in the PHEV) to provide a nominal 14V in order to supply electricity to the electrical components, as well as to recharge the auxiliary battery. The DC/DC Converter is equivalent to the alternator on a traditional car as so I would guess that it keeps the 12V battery 'topped-up' in pretty much the same way. I've no idea exactly how 'smart' the this system is (and I'm not sure that I really care!)

[ernieb]

Philip I agree it does the job. If I sit in my car after a few days parked and set it to READY mode I can hear the whines and clicks as systems clunk into life as well after awhile a blower which I assume is a cooling fan for the DC to DC converter. I also think in this state it powers the cars services, radio etc., and charges the battery so no juice is taken from the 12v Battery. My manual says that if you are going to sit in the car with the radio on just put the car into READY mode the massive traction Battery is then taking all the necessary steps to power the car and charge the Battery, it’s all sorted.

[philip42h]

31 minutes ago, ernieb said:

Philip I agree it does the job. If I sit in my car after a few days parked and set it to READY mode I can hear the whines and clicks as systems clunk into life as well after awhile a blower which I assume is a cooling fan for the DC to DC converter. I also think in this state it powers the cars services, radio etc., and charges the battery so no juice is taken from the 12v battery. My manual says that if you are going to sit in the car with the radio on just put the car into READY mode the massive traction battery is then taking all the necessary steps to power the car and charge the battery, it’s all sorted.

If I were to guess, I'd expect the DC to DC converter to act simply as a 'smart charger' to keep the 12V Battery full charged. And the 12V Battery would power all the 12V components exactly as it would in a traditional car. But that's just a guess / what I might do if designing the car ...

And the whines, clicks and clunk are amazing - it's even 'worse' than our fridge! 😁

[Yugguy1970]

Yep, driving a Hybrid is certainly an event 😁

[ernieb]

22 minutes ago, Yugguy1970 said:

Yep, driving a Hybrid is certainly an event 😁

You do think sometimes that Rick Wakeman had something to do with the orchestration? (Shows my age…..)

[Yugguy1970]

One of my favourite albums

 

 

[PeteB]

3 hours ago, ernieb said:

...I carry a Lithium battery booster accessible from inside the car. (it's actually in the boot but I have a boot box with a pouch that i can access from inside the car by lowering the rear seat)...

Just a thought Ernie, do you deadlock the car?  If so, if the 12V's really flat you'll only be able to unlock the driver's door with the emergency key until you can get some extra power into the system (unless the PHEV works differently in some way to the RAV4 ordinaire).

That would certainly prevent me from getting to the rear seat, though a fitter, leaner (ok, less fat!) person could no doubt manage it(*).  If you've also got an electric driver's seat and therefore can't adjust it, maybe another obstacle?

My 12V jumpstarter came in a neat carry case which holds the lithium Battery, leads and chargers, and fits nicely in the seatback pocket.

(*) In the early days of the Gen 2 Prius there were lots of amusing tales of owners doing all sorts of contortions to climb into the boot to remove some trim on the back door that gave access to an internal release handle so they could connect jump leads or a jumpstarter to the 12V Battery.  As well as explaining about the jump terminals under the bonnet, the 'technical term' RTFM was bandied about quite a bit in that era!  (The issue didn't arise in the Gen 1 Prius - it was a saloon and the boot could be opened with the key or a mechanical cable release handle by the driver's seat.)

[ernieb]

@PeteB, good thought I’d originally put in under the drivers seat where I’d previously stored it in my last couple of cars. So I think it’s best I move it to a fully internal location. I’ll hunt about to see what’s the best place. 
Thanks for the input, don’t you just love forums?

[Yugguy1970]

Looking in my boot I could see the Battery but to get to it looks difficult, a lot of plastic lining would need to be removed.   I guess that's why there are jump start points under the bonnet.

All this talk of 12V Battery flattening is getting even me paranoid about leaving the car in say an airport car park for 2 weeks.

[PeteB]

1 hour ago, Yugguy1970 said:

...All this talk of 12V battery flattening is getting even me paranoid about leaving the car in say an airport car park for 2 weeks.

You'd be very unlucky to have a problem after two weeks unless your Battery is already weakening or the car has an electrical fault.  If you've driven any distance to the airport then your Battery will almost certainly start with a good charge level.

I've left other Toyota Hybrids for almost a month with no problem and my RAV got left for almost 2 weeks during lockdowns.  It sat in Ready Mode for 20 minutes every 10-12 days in an abundance of caution.

That said, I feel more comfortable knowing I've got the jump starter handy, but that's just me.

[ernieb]

@PeteB, I’d agree with that unless it was very cold and left out in the open when it might be a little more likely to fail.

[Yugguy1970]

Yeah to be honest I agree with you. 

I'm not sure, apart from a slightly smaller capacity, why we think the 12v in a hybrid gets any more load when the car is off, than the Battery in any other car.

My 2019 Focus had remote management and comms and all the stuff the RAV has and it was fine after 3 weeks sat in a carpark.

[Nick72]

11 hours ago, ernieb said:

If you have a convenient mains supply then the trickle charge route is a probably the best option and some people have installed a connector so that they can just 'plug' in the charger. In fact some chargers come with the kit or it can be bought as an option. As I've said elsewhere I carry a Lithium battery booster accessible from inside the car. (it's actually in the boot but I have a boot box with a pouch that i can access from inside the car by lowering the rear seat). It's powerful enough to start a normal car if required and I've been a good samaritan to a number of neighbours since I bought it, better than the 12v standard battery I used to have by miles.

Thanks Ernie. No garage or convenient mains connector so that sounds like the booster route for me. So do you just connect the booster in parallel then start the car (ready mode)? Then presumably the car begins charging the little Battery from the big Battery?

[Nick72]

9 hours ago, philip42h said:

According to the handbook: "The 12-volt battery is located in the right-hand side of luggage compartment." So, it's in the boot, behind / beneath the trim. I believe my car must have one but I've never seen it! 😉

There is an "exclusive jump starting terminal" within the fuse box, under the bonnet - which is more easily accessible. I use this to trickle charge the battery if/when lockdown etc. has prevented normal use of the car.

When in Ready mode, the DC/DC Converter steps down the high voltage from the traction battery (244.8V in the HEV, 355.2V in the PHEV) to provide a nominal 14V in order to supply electricity to the electrical components, as well as to recharge the auxiliary battery. The DC/DC Converter is equivalent to the alternator on a traditional car as so I would guess that it keeps the 12V battery 'topped-up' in pretty much the same way. I've no idea exactly how 'smart' the this system is (and I'm not sure that I really care!)

That's good to know about the jump start terminals under the bonnet. Whereabouts is that since the powered rear door isn't going to open if the Battery is dead?

And when you trickle charge it this route do you have the bonnet up or can you close it if you route the cables somehow?

[Nick72]

7 hours ago, PeteB said:

Just a thought Ernie, do you deadlock the car?  If so, if the 12V's really flat you'll only be able to unlock the driver's door with the emergency key until you can get some extra power into the system (unless the PHEV works differently in some way to the RAV4 ordinaire).

That would certainly prevent me from getting to the rear seat, though a fitter, leaner (ok, less fat!) person could no doubt manage it(*).  If you've also got an electric driver's seat and therefore can't adjust it, maybe another obstacle?

My 12V jumpstarter came in a neat carry case which holds the lithium battery, leads and chargers, and fits nicely in the seatback pocket.

(*) In the early days of the Gen 2 Prius there were lots of amusing tales of owners doing all sorts of contortions to climb into the boot to remove some trim on the back door that gave access to an internal release handle so they could connect jump leads or a jumpstarter to the 12V battery.  As well as explaining about the jump terminals under the bonnet, the 'technical term' RTFM was bandied about quite a bit in that era!  (The issue didn't arise in the Gen 1 Prius - it was a saloon and the boot could be opened with the key or a mechanical cable release handle by the driver's seat.)

Whoa. How do you deadlock the car? I might be looking mine all wrong. I just press the lock button on the key fob. Is there another way?

[Nick72]

5 hours ago, Yugguy1970 said:

Looking in my boot I could see the battery but to get to it looks difficult, a lot of plastic lining would need to be removed.   I guess that's why there are jump start points under the bonnet.

All this talk of 12V battery flattening is getting even me paranoid about leaving the car in say an airport car park for 2 weeks.

Yeh and really any reasonably designed car should be capable of being left for 4 weeks since that's probably a long holiday for some. 21 days is the longest one I've been on. Shouldn't have to d*** about.

[PeteB]

Just now, Nick72 said:

Whoa. How do you deadlock the car? I might be looking mine all wrong. I just press the lock button on the key fob. Is there another way?

Press the lock button a second time within 5 seconds.  Also works with keyless locking; touch the line on the door handle to lock it, second touch within 5 seconds to deadlock.

[Nick72]

Can someone recommend a good jump starter and can point me to the front fuse box jump start terminals? I'll just write down or print it off and leave it in the centre console with the jump starter if it fits in there. Compact preferred.