Toyota hybrid 12v battery draining constantly.

The car doesn't need to be replaced the fault needs to be diagnosed and rectified.

It's under guarantee so the dealer will fix it free of charge.

As the other poster says those cars have a reputation for reliability.

Toyota is the most reliable brand on the road.

As above something needs to be rectified, Toyota are usually excellent for back up

My wife's aunt has a 232 Yaris Cross. She had the same issue. The first time was within about 3 months of ownership, there was a bit of back and forth but after going back to Toyota the third time they admitted there was a fault and replaced the 12V battery, she thinks they said they did something else too but doesn't know what. Problem never came back, and that's close to a year now.

I'd be bringing it back to them.

Very strange to feel that way because of a faulty 12v battery. Just get it fixed and move on with life

Is it still under warranty?

I remember in the early 2000’s their red colour cars suffered terrible lacquer peel and they denied responsibility until a big group of owners in the UK got together and forced them to fix it under warranty. Not surprising if this drain is a widespread issue that they’ll try to avoid it.

Their history with honouring warranty calims and recalls isn’t great.

The auxiliary battery needs to to be charged, same as all the other cars with traditional Altenator systems. Small journeys and idle time add up to the battery being discharged more than charged and the general health of the battery depleting over time, there is quite and easy was to fix this issue. Put the car into “Ready” for 1 hour every 2 weeks.

I've skipped thru all the comments..

Neighbors elderly parents have the same issue with a 2021 Toyota hybrid.

The main dealers solution was to give it a good drive of 60km every week.

Probably because most owners drive their cars more.

How often is the Corolla in question actually driven and how much mileage per month ?

I remember a relation bought a low mileage Lexus LS400.

Previous owner was an elderly lady who only drove it once a week to the shops.

The car was always garaged and had a trickle charger installed under the bonnet which she kept plugged in.

I get your point.

Presumably the dealer knew her usage requirements.

Still someone is going to get a good car when she trades in.

What is she getting ?

Does a Corrola Hybrid use an alternator even? If not, then the HV system should be charing the 12V system even when the car is off. I know the below part isn't necessarily in the Corrola, but it's a mature tech, in lots of HEV, PHEV and BEVs today.

https://www.toyota-industries.com/products/automobile/electronics/converter/index.html

Almost all automotive electronics today use 12V. Toyota, and their suppliers don't make door locks, windows switches and windscreen wipers, etc. specifically for hybird or electric cars. The easiest, cheapest and safest thing to do is to also include a 12V battery.

Changes are coming down the tracks, slowly but surely, but there won't even be an EV on the market for 10+ years which has just a single high voltage battery.

In general, Toyota Hybrids are the most reliable cars on the road. They are the benchmark. Don't let a single bad battery fool you into thinking otherwise.

As a counter point - I had major trouble with a PHEV (moreso the labour cost than the actual issue tbh, but it had 3 batteries HV, 12V and a Stop/Start), and I now have a straight Petrol car, 3.5yrs old with a single battery.

It was doing some funny things like losing my settings on the radio, but I put it down to crappy software on a new car. I went to hardwire a dashcam recently, and found while testing it that in fact the 12V battery is very weak. The very same could happen on a car you switch to.

It could be that the battery in her previous car was of a better quality and had more Ahs.

Manufacturers trying to cut costs are starting to skimp on batteries, we just just replaced a battery in our Hyundai after 2.5 years due to it dropping below 12V.

The new battery is 65 Ah compared to the fitted 60Ah, seems to be ok so far but time will tell.

Which non-hybrid Lexus did she have? It's likely not terribly new. You still haven't said how old this car is either, or if it's still under warranty. I'm happy to be proven wrong, but I think the car is a few years older than we're being led to believe and simply needs a new battery. One deep discharge can effect a battery forever.

Newer cars, in general, will drain their 12V batteries more quickly than old cars, because they're never truly off. Phone app connectivity, EU mandated Emergency Call systems, keyless entry, etc. all draw small amounts of current even when the car is parked.

Did her last car have those features?

That said, 10 minutes to the shops every second day should be fine to keep the battery topped up, as the ECU will recognise the low state of charge, and charge the battery more aggressively for that 10 minutes.

I can guarantee you that Toyota will never, ever stand over minimum driving periods in writing, even if the mechanic is correct, and they see it from time to time. I work in automotive electronics, and while I can't post the full quote, I can say that I'm looking at a spec here from a major OEM which states "…consideration must be given to customers who drive vey little…"

Is the car being manually put into ECO mode? This can/will deo everything it can to save fuel, and may limit the battery charging, and is for when you know you'll be doing a log drive say, and don't want to unnecessarily waste fuel charging the battery as quicky as possible at the beginning of your journey.

You could try and take out the keyless entry fuse, and if there is one for a telematics unit (E-Call / Phone), to see if that helps, but again, these will be a feature of newer cars too and may cause error codes on the car depending on how they're powered and monitored.

Again, think it's simply a bad battery, but an elderly person I know uses a trickle charger to keep their second which they really never use, topped up. A simple magnet charging adapter makes life very easy. https://www.amazon.co.uk/ChargeSafe-Magnetic-Trickle-Charger-Adapter-Black/dp/B0CV3DLFRX

Adding a couple of months for manufacture, delivery, etc - the car is between 5 and 6 years old now.

It is on it's original battery? If so, it's time for a new one.

There is only so much testing that a dealership will be willing and able to do in the time allocated for a service. The dealer isn't going to admit that their testing capacity is limited, and advising a long dirve every so often is really just trying to save her a few quid as they don't want to dump a bill for a battery "just in case" on her.

The fact is though, the car isn't starting, and without an other obvious fault - the default course of action is to swap the battery.

Again, her older car is very unlikely to have some of the features of the new car which can and do cause some battery drain - that's not necessarily an issue with Toyota Hybrids, and so any new car could, and likely will have the same issues.

You say that the battery is "fine", but the fact of the matter is that it doesn't start the car every time.

A full test of the battery would include leaving it sitting idle for 2-3 days as your aunt does between drives - which wouldn't be in the interest of most dealers, and I seriously doubt was done. Do you have a copy of a report from a dedicated battery tester, or did a mechanic just say it was "fine"?

You didn't know yourself that the car even had a 12V battery, or why it has one in addition to the HV battery, so with the best will in the world I don't think you're the one to be advising her to change away from probably the most reliable car on the planet, costing thousands in depreciation, to solve a problem she will most likely have in a different car of the same age too.

I've explained in detail why a newer car will drain batteries faster than an old one, and I (and other posters) have tried to be helpful in suggesting that the battery is replaced which in all likelihood will solve the problem, but you're more interested in an entirely new car.

How many times has this happened? You said "initially" and then "again", is that twice, or more?

You also said "newest version" and "new Toyota", but you have since said it's a six year old car.

It's nearly too little for most modern cars. The amount of tech that now sort of runs in a standby yet always on mode while the car is off is the issue. It's a big issue in the Toyota hybrids because the 12v battery is small.

Simpler older cars had less of this and also had in general 12v batteries that were a size or two bigger than the car would even need to simply start. So it wasn't really an issue.

My advice would be get the measuring tape out and find and fit the largest Ah battery you can to the car. I see it mentioned online that some are putting 52Ah batteries into the Toyota chr in place of the factory 45Ah. I'd be seeing if you could even go a size bigger If at all possible. If ya can't do this then bring the car to a regular mechanic and explain the situation. Dealers won't do this and would be way dearer anyways.

You're going down a blind alley on the Toyota hybrids being unreliable in general thought process.

They're literally one of the most reliable family of cars on the road.

Just last week a stat on the top 3 highest cumulative mileage yet still on the road cars in the UK came out.

1. VW Passat's

2. Toyota prius'

3. Skoda Octavia's

Ya everyone is making a different product for the European market compared to what they used to unfortunately or fortunately depending on how ya look at things. It's the level of tech in modern cars now.

Changing/upgrading a 12v battery to hopefully fix a problem is trivial in the grand scheme of things when you compare it to some of the possible repair bills you could be landed with in other alternative cars.

But look if she's hell bent on changing the car and willing to absorb the financial hit then there's nothing wrong with that, after all it's her decision and whatever makes her happy should be the priority.

Realistically she should go for a full electric car considering the miniscule amount of driving she does although you'd need to be sure it has features built in to insure the 12v battery can hack the super short trips. As far as I know this scenario was an issue on some electric cars before.

Failing that a simple bog standard exceptionally low on tech automatic naturally aspirated petrol car should be the target. Not exactly the easiest thing to find these days.