battery flat

[Catlover]

9 hours ago, ColinB said:

The AA man showed me the connection point under the bonnet, but with the tailgate open it's easier to connect straight to the battery. 

Point I was trying to make is that this time you managed to access the boot area, when the 12v is really flat you will struggle to do that.

[ColinB]

On 8/28/2021 at 5:06 PM, ColinB said:

Just had the battery go flat again on my C-HR, hasn't used it much recently so it started sulking. It started immediately when I connected my booster pack and I have it a run. 

The tailgate opened easily so I could get to the booster pack and the battery easily, however I'll have to find somewhere else on my RAV4 when it turns up as it has a power tailgate. 

I've now bought a solar charger that I'll keep connected to the Battery when not using the car, so hopefully I won't have that trouble again. 

[LesU]

Also beware that if the 12V Battery goes too low then it resets the history of the engine performance. I had a similar occurrence earlier in the year and when my service was due not long after the Battery episode, the traction Battery health check could not be carried out. I've had to do over 600 miles before taking it back in for the check, which it passed.

[PeteB]

While on the subject, when the 12V Battery failed on my last Prius (2016 Gen 4) I got lots of messages when I started the car with the jump starter, including:

• MIL light & triangle
• Hybrid System Malfunction
• Lane Departure Alert Malfunction
• Pre-Collision System Malfunction
• Intelligent Clearance Sonar Malfunction
• Braking Pressure Low - Visit Your Dealer

They gradually cleared over the next dozen or so restarts.  I could not use Cruise Control until some of the had cleared either.

Before the cars came with the "Safety Sense" package, a low 12V Battery might bring on the MIL Light and Triangle, and a message on the infotainment screen something like "Park on Level Ground and select P".

Edited September 1, 2021 by PeteB
Oops - said "I could use Cruise Control" instead of "I could NOT use Cruise Control"

[ernieb]

This is what the manual says needs to be initialised after a Battery disconnection (or change).

 

[Nick72]

Really stupid question I'm sure but...

What is accessory mode versus Ready mode? How do you enable either? 

It sounds like if you are sitting there listening to the radio then you need to be in Ready mode?

[PeteB]

Accessory Mode is entered when everything is off and you press the Start button without a foot on the brake.  This only powers up the accessory circuits including the infotainment display.  "Accessory" is displayed on the speedo screen.

A second press of the Start button without pressing the brake pedal enters Ignition Mode.  This is like turning the key on an older car until all the warning lights come on without starting the engine.  Most electrical systems will work, like electric windows, wipers etc.  This all works off the 12V Battery.

Ready Mode is when you press Start with a foot on the brake.  The car can be driven, the petrol engine will run when necessary and the 12V Battery is charged by the HV (High Voltage Traction) Battery.

And yes, it's safer to use Ready Mode when listening to the radio.

[Nick72]

36 minutes ago, PeteB said:

Accessory Mode is entered when everything is off and you press the Start button without a foot on the brake.  This only powers up the accessory circuits including the infotainment display.  "Accessory" is displayed on the speedo screen.

A second press of the Start button without pressing the brake pedal enters Ignition Mode.  This is like turning the key on an older car until all the warning lights come on without starting the engine.  Most electrical systems will work, like electric windows, wipers etc.  This all works off the 12V battery.

Ready Mode is when you press Start with a foot on the brake.  The car can be driven, the petrol engine will run when necessary and the 12V battery is charged by the HV (High Voltage Traction) battery.

And yes, it's safer to use Ready Mode when listening to the radio.

That's brilliant thanks. I had no idea at all.

Wonder why they even have those two modes (accessory and ignition) if the 12V Battery is so titchy. 

 

And My Room Mode is only when you are plugged in to a wall box and only takes power for air con, radio, etc. from the supply from the wall box? I just press start for that?

[PeteB]

9 minutes ago, Nick72 said:

...Wonder why they even have those two modes (accessory and ignition) if the 12V battery is so titchy...

Indeed - the manual even recommends you don't use these modes!

I suppose it's to maintain compatibility with 'ordinary' cars in the same way as there's no real need to use electricity to make the car creep like a conventional auto when no pedals are pressed while in D or R.  For my last 20 years and 330,000+ miles in Hybrids I've wished there was an option to cancel the creep (like Teslas have), but we now have Brake Hold to save the day (at the cost of shining brake lights in the faces of following drivers!).  

And why do we have to select Brake Hold every time we start the car?  Surely it's not beyond the wit of man to write software that says "enable Brake Hold when the button was last used to switch it on and the driver's seat belt is on and the driver's door is shut"!

Can't help with "Room Mode" as I'm not familiar with, having as I do a RAV4 ordinaire!

[Yugguy1970]

My previous Focus would complain if you sat with the ignition on for too long and would ask you to start the engine.

I really like the hold behaviour as you can set it separately to the handbrake. I have autohold off but auto parking brake on.  The brake comes off when I move from P.to D which makes sense to me.

My auto hold setting stays off permanently.

Creep is very useful to me for getting on my drive but that could be a user setting too I guess.

[philip42h]

7 hours ago, PeteB said:

And why do we have to select Brake Hold every time we start the car?

We don't Pete, you may feel the need but I suspect most of us just drive the car as it is ... 😉

[Roy124]

I found it useful after my first experience to log the Battery voltage every day. Immediately after a drive it might register just over 13v dropping quickly to around 12.7v.  It would continue to drop each day between 0.1 and 0.3v.

I didn't check with the new Battery as it always worked.  I started checking 3 days ago. Initially it was 13.8v. The following day it was 14.2v and 13.7v today. 

It seems to show that a Battery with a weak cell or two will loose charge quickly.  

Ideally check how your car battery maintains its charge while everything is working. After your first flat battery start checking again. If it holds charge you are probably OK. 

If it loses charge you have evidence to show the garage. Volt meters are cheap. 

 

 

[ernieb]

I have a useful little gadget that fits into the 12v accessory socket (cigarette lighter in old money) which has a digital volt meter read out of the 12v Battery.  I keep it in the centre consul pocket just in case.

[Roy124]

14 minutes ago, philip42h said:

We don't Pete, you may feel the need but I suspect most of us just drive the car as it is ... 😉

Philip you are being mischievous. 

An alternative is to use ACC and trust it.  This works with queuing traffic but if you are first at lights or a busy crossing I much prefer brake hold (I must check the point about brake lights.)

 

[ernieb]

I guess it’s just a belt and braces measure ensuring the driver is in attendance. I’m so used to doing it it’s second nature.

[Yugguy1970]

Does autohold illuminate the brake lights?

I've never got on with autohold on other cars as it has always given a lurch as it applies drive first then releases the brake.  Havent tried it on the RAV yet as I havent driven it that much.

Stopstart on an ICE normal slush auto was the worst though, and positively dangerous.  If you need to pull out into a busy road, the car has to start the engine, and apply drive and this takes time.

My Focus at least had a sensor on the brake pedal, so if you only pressed it down lightly, enough to keep at a stop, it wouldn't stop the engine.  You had to press it deeper than that.  This allowed you to control it, which is all I have ever asked of any modern driver "aid".  Choice.

[ernieb]

I’m not sure about the light illumination I’d have to check but the action itself I find very smooth with a clean transition from stationary to drive.

I’ve found with the PHEV in EV mode the system is very effective  under normal everyday driving and monitoring the slow down to stationary almost holding the car in a ready mode with the lightest of touches on the brake.

[philip42h]

1 hour ago, Roy124 said:

Philip you are being mischievous. 

Who? Me? OK, yes, you are right, I am. Though to be honest I'm getting rather bored of comments along the lines:

• Why didn't Toyota design the RAV4 to my liking / specification?
• In the US ...
• On my previous car ...

And this is a thread on the tendency of the 12v auxiliary Battery to run flat ... which has degenerated into a discussion on the braking system. This place used to be a bit **** about folk keeping on topic, but now it seems to have drifted rather too far the other way ... 😉

[Yugguy1970]

Agree with that yes.  The RAV has many better features than the Focus I had, but there are things that it had that the RAV doesn't.

However, all the specs are available online.

I researched both the Corolla and the RAV and decided for each one which trim level I wanted, and what I was and wasn't prepared to pay for.

That said, threads often do wander, it's the nature of them, they are basically a protracted conversation.

[Catlover]

2 hours ago, ernieb said:

I have a useful little gadget that fits into the 12v accessory socket (cigarette lighter in old money) which has a digital volt meter read out of the 12v battery.  I keep it in the centre consul pocket just in case.

I have one as well, but it also has 2 usb sockets, one feeding the dash cam (I dont want to wire in pemanantly) and the other my mobile phone for charging/waze.

[ernieb]

@Catlover, so simple, relatively inexpensive and immediately to hand if the 12v is suspected of playing up.  I think the extra USB sockets is a bonus.

[Peterd23]

3 hours ago, Yugguy1970 said:

Does autohold illuminate the brake lights?

I

 

Yes, brake lights stay on in hold. Don't think there is any way round this. A minor disappointment.

[Gerg]

4 hours ago, Roy124 said:

I started checking 3 days ago. Initially it was 13.8v. The following day it was 14.2v and 13.7v today. 

I have a couple  of accessory socket plug-in voltmeters.  Some months back, they were showing readings that were slightly different to what I was expecting - out by about 0.15 volts. 

If that was consistant then I could allow for that, no problem, but it turns out it wasn't consistant.  I attached them to a reliable, adjustable bench power supply, and the readings were adrift, but by a small unpredictable amount, especially if the PSU output voltage being measured was slowly rising or falling.  But their readings were never more than 0.15 volts adrift.

Your ones might be different, of course!  Just something to be aware of.

 

[ernieb]

@greg, I found mine to be accurate enough to tell me the Battery state and yours seems to be pretty good at 1.25%?

[roger_37]

35 minutes ago, ernieb said:

@greg, I found mine to be accurate enough to tell me the battery state and yours seems to be pretty good at 1.25%?

can i be so bold and ask which one you have ,as i would like to get one