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Problem with 12v battery on RAV4 Hybrid


DonMac
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I’ve ordered an Excel FWD and expecting delivery in October. I’ve been concerned over the past days as I’ve found a lot of examples of problems with the 12v Battery going flat. In normal times ,which I hope will return soon ,we travel to see our children overseas and the last thing I want is to get back to the airport car park after a long flight to find the car Battery flat. I also understand it can happen on a more random basis not just after a long period of inactivity. I’d appreciate it if anyone can tell he how serious a problem this is and whether Toyota have cured it and if not why.

Many thanks

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The issue first came to light during the first lockdown from March 2020, and is generally caused by the vehicle not being used for a period of time or frequent short journeys. See the following pinned topic and Toyota's recommendation re using ready mode:

 

 

 

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My hybrid Corolla is driven approx 24 miles each day in two trips of 12 mile which takes about 25 mins each way on different types of road and no issues. 

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1 hour ago, DonMac said:

I’ve ordered an Excel FWD and expecting delivery in October. I’ve been concerned over the past days as I’ve found a lot of examples of problems with the 12v battery going flat. In normal times ,which I hope will return soon ,we travel to see our children overseas and the last thing I want is to get back to the airport car park after a long flight to find the car battery flat. I also understand it can happen on a more random basis not just after a long period of inactivity. I’d appreciate it if anyone can tell he how serious a problem this is and whether Toyota have cured it and if not why.

Many thanks

It's a minor issue rather than a real problem, but something to be aware of. The hybrid system incorporates a small 12v auxiliary Battery that keeps necessary electronic systems alive while the car is not in Ready mode (i.e. off) - in Ready mode the auxiliary Battery is charged via the traction Battery. Being small, it doesn't hold a massive amount of charge, but there again, it doesn't have that much to do. If you run the car for around 1 hour a week you'll never notice a problem; if you leave the car unattended and idle for over a month you may well find that it won't start when you get back to it.

During lockdown folk didn't get out much and encountered issues that, in their normal lives, they wouldn't have. If you are laying the car up for a while, put it on trickle charge if you can; if you are going to abandon the car in a long stay car park for six weeks, invest in the smallest available jump-start pack. You need the 'tiniest' amount of charge to restore the Battery to a level sufficient to get into Ready mode and then the traction Battery can sort out the rest.

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On previous cars I’ve carried a Lithium Ion Battery jump starter, small and compact it is easy to store and holds its charge really well. It will start a 2ltr automatic all I’ve tested it on but rated at 3ltr, on a cold winters day and also has 5volt USB outlets. Relatively inexpensive and a great emergency back up. I carry it in the RAV but will invest in a smart trickle charger.

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I've had no problems with my RAV4 over 2 years 17,000 miles.  During the lockdowns I sat in the car in READY mode for half an hour every 10 days or so, which prevented any problems.

Like Ernie I keep a tiny jump starter in the seatback pocket (don't use the boot, it's hard to access if the 1V Battery does go flat).  I've had to use it on a previous Hybrid, and have started other people's 'ordinary' (non-Hybrid) cars wi8th it too.

see link

 

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This is also reported as an issue on the C-HR and it happened to mine. Took the AA 5 minutes to get it going once they arrived, so I followed the advice of others on the C-HR forum and bought a small Battery charger pack which lives in the boot. It is small enough to take away on the motorbike when touring as well. 

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5 minutes ago, ColinB said:

... I followed the advice of others on the C-HR forum and bought a small battery charger pack which lives in the boot...

Just bear in mind that if the 12V battery's really flat, the electric boot opener won't work and getting to it from inside the car could be a challenge (or impossible if you're built like me!)

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1 hour ago, PeteB said:

Just bear in mind that if the 12V battery's really flat, the electric boot opener won't work and getting to it from inside the car could be a challenge (or impossible if you're built like me!)

Good point, my car unlocked OK, it just wouldn't start. My RAV4, when it arrives, has a power tailgate so that might be a problem. 🤔

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As I understand it the12 volt Battery is charged from the traction Battery.  So if you know you are not going to use the car for a while make sure the traction Battery has a very high charge level before parking up.  I have done this with my Mk 4 and never had a problem even when not using the car for up to 14 days.

There seems to be reports of problems with the 12 volt Battery on American sites and mention is made of a software upgrade.

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R4P, My understanding is that the AGM 12 volt Battery will only be charged if the car is either on the move or in ready mode, so for clarification just having a full traction Battery will not charge the 12 volt Battery with out intervention.  I was surprised that during the traction Battery charge process at home or from the charge station that the 12 volt Battery was not also topped up.

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Thanks for everyones comments, very useful.

My initial query was to do with reports from the US regarding problems with 12v Battery being drained which I thought would probably also be valid in the UK as it's basically the same car, albeit Japanese built rather than US.

I 've raised it with my dealer and he replied saying for cars built after March 2021 it should no longer be a problem, I'm going to query this  but does anyone know if anything new happened in March that changed the position? Like a design change or availability of new firmware.

He also suggested that if I was not going to use the car for sometime I should isolate the Battery and also said there was an "available installation which will cut off the Battery and prevent from draining" Anyone heard of this? Also if you isolate the Battery won't you loose all the info in the various systems. How do you isolate the Battery and can you then lock the car?

And, finally if the Battery is flat can you still unlock the door, to access the engine compartment and allow you to use a charger?

Thanks for any comments

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There's an emergency key in the fob that will unlock the driver's door.  If the car was deadlocked, no other doors can be opened until power is restored.

Beware the key is small and can be hard to turn.  There have been many claims that it doesn't work, but usually it just needs a bit more force.

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I don’t understand advice that says disconnect the 12v Battery as I’d have assumed that this would potentially cause all kinds of issues including deactivating the alarm system. If I could not either use the car periodically or use a mains trickle charger I’d probably resort to using either a Lithium Ion Battery or standard car Battery to provide additional power linked internally to the car’s AGM Battery.

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1 hour ago, PeteB said:

There's an emergency key in the fob that will unlock the driver's door.  If the car was deadlocked, no other doors can be opened until power is restored.

Beware the key is small and can be hard to turn.  There have been many claims that it doesn't work, but usually it just needs a bit more force.

I suspect that the emergency key gets hard to turn due to lack of use. It is worth using it now and again to keep some free movement.

It is a useful key, if you want to leave the car in 'ready' state while updating the maps for instance (yes, I know the rule about leaving it unattended), this key will lock the car. It won't set the alarm though - which can be useful in itself.

The longest I have left a hybrid (this was an Auris) was three weeks in summer. Gave it a decent run before parking up, made sure everything was turned off and then left it locked on our driveway without setting the alarm. No problems on return. Fortunately we lived somewhere safe (if anywhere can be) and this didn't pose too much of a risk.

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I’d recommend a CTEK MXS 5.0 Battery charger - a full charge with that will keep your car sufficiently charged to last a couple of weeks at the airport. 

https://www.tayna.co.uk/battery-chargers/ctek/mxs5-0/?gclid=CjwKCAjw9aiIBhA1EiwAJ_GTSvL2vTL-b0YuDV_i9wgAeQvN2W9W8DRnClJ4PUQ1KYuWoqCnfR_SrBoCX88QAvD_BwE


 

 

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  • 3 weeks later...

My Rav 4 is 2019 and I have had from new. Yesterday it wouldn’t start and appeared the starter Battery was dead.  Got jump started this morning, drove to garage and they tested the Battery with lights on, air con on etc and it depleted very fast.  Engineer told me the starter Battery is very small and not really suitable and it is actually classed as a consumable but as they were able to test as faulty it was replaced free. He told me it’s a common fault with all hybrids and they should be recalled but as the Battery is consumable they won’t do it.  Recovery company told me in the last week they have jump started 15 hybrids of all different brands. 
 

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There's no denying the 12V Battery is a bit of an Achilles heel on Toyota Hybrids, but certainly the 2 times I've needed a new one (once on a Gen 1 Prius, once on a Gen 4), my dealer replaced under warranty with no quibble at all.

Because they don't have to start the engine, and to save weight and space they use a small Battery.  With care, they can last a long time - my 2nd Gen 1 Prius still had the original Battery when I sold it at 9 years old with 163,000 miles on it.

It's best to avoid using accessory mode or ignition mode (all warning lights on, but not "Ready").  If sitting in the car, have it in Ready mode (green "Ready" light on) of fully off.  Even if the engine's not running, the 12V Battery is kept charged by the big Battery.  Also, try not to use the electric boot opener or seat adjustment too much when the car is off.

More problems than normal arose during lockdowns so some people resorted to a trickle charger, others (like me) sat in the car for 20-30 minutes in Ready Mode every 10 days or so to keep it topped up.

See my post above on 2nd August - for peace of mind some of us keep a small jump starter in the car, just in case.  Don't keep it in the boot - it the 12V battery's really flat, getting into the boot can be very challenging!  Mine's in a little case and is small enough to live in the seat-back pocket.

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My C-HR had this problem, AA started it within the hour but I bought a small jump Battery pack that lives in the boot. I will have to rethink this for my RAV4 when it arrives as it has a power tailgate. 

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Might be worth a quick reminder that if the Battery does go flat you don't need to access it directly via the boot. In the main fuse box under the bonnet there is a contact post which is under a hinged red cover. Any twelve volt booster or intelligent charger positive lead may be attached here using a bare metal part of the engine or one of the top suspension mount bolts for the earth connection.  Just remember that once the car has achieved switch on to ready mode there will be a high charge rate from the traction Battery even if the engine is not running. So as per the manual the safest method for jump starting is to allow your donor vehicle or Battery pack, engine NOT running, to boost the Battery for about 5 minutes then disconnect it before switching to ready mode. 

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1 hour ago, ColinB said:

My C-HR had this problem, AA started it within the hour but I bought a small jump battery pack that lives in the boot. I will have to rethink this for my RAV4 when it arrives as it has a power tailgate. 

Power gate or not, if the 12v Battery goes flat you may be only able to open the driver door (by key), so if you keep the jump Battery pack in the boot you going to have to scramble for it.  As Pete B does, put it in the pocket behind the driver seat, thats what i do and i probably got the idea from Pete some 3 years ago. Pete has had a few Prius hybrids over the years and got lots of experiance.

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1 hour ago, ColinB said:

My C-HR had this problem, AA started it within the hour but I bought a small jump battery pack that lives in the boot. I will have to rethink this for my RAV4 when it arrives as it has a power tailgate. 

You'll be no better off in the C-HR (or almost all other Toyota Hybrids) - the non powered boots still have an electronic opener! (when there's enough juice in the 12V!

PS got to the bottom of the posts and saw Joe's message after I'd sent this!

Back in the early Hybrid days there were a number of amusing posts from people who didn't 'RTFM' who did all sorts of contortions to clamber into the boot to jump start!  This didn't affect the Gen 1 Prius - it was a saloon and the boot could be opened with a key (deadlocking didn't affect the boot) plus there was a cable release next to the driver's seat.  Just as well, as the Gen 1 didn't have the jump start terminals under the bonnet (IIRC).

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13 minutes ago, Catlover said:

...Pete has had a few Prius hybrids over the years and got lots of experiance.

In fairness I should mention that I've been chatting on various boards to other owners, enthusiasts and Toyota people for some 20 years and an awful lot of my knowledge comes from others.  Particularly in the early Gen 1 Prius days there were a lot of people with engineering, electronics or other skills that were quite adventurous in their experimentation.

After owning my first 2000 model Prius for 6 months and driving 12,000 miles in it I was absolutely furious with Toyota to discover I'd done all those miles in a car that had a fully working Cruise Control system (right down to the dash indicator bulbs) and only needed the switch to make it work - a US site gave the part numbers (it needed a different brake light switch too) and for £160 incl vat my dealer ordered and fitted them.

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37 minutes ago, PeteB said:

Particularly in the early Gen 1 Prius days there were a lot of people with engineering, electronics or other skills that were quite adventurous in their experimentation.

I would love to hear what these guys were trying out Pete.

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42 minutes ago, PeteB said:

 

After owning my first 2000 model Prius for 6 months and driving 12,000 miles in it I was absolutely furious with Toyota to discover I'd done all those miles in a car that had a fully working Cruise Control system (right down to the dash indicator bulbs) and only needed the switch to make it work - a US site gave the part numbers (it needed a different brake light switch too) and for £160 incl vat my dealer ordered and fitted them.

That happens a lot.  I know my wife's Fiesta has all the prewiring for cruise and would only need the steering wheel button unit changed.  

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