What the car dealers don't tell you when buying a new Toyota Hybrid car, and the 12 Volt battery.

iBaxter · 07-01-2026 02:33PM #1

My elderly parents both have Toyota Hybrid cars. His is a 1 year old Corolla Cross and her's is a 3 year old Yaris, both are Hybrids. Most of their journeys are short hops within a 10 Kilometer range of the house, in the suburbs. Both cars have each failed to start over the past 2 weeks. With the Corolla it happened in a supermarket car park and the Yaris in the driveway of the house. They were able to call a 24 hour rescue service which jumped the battery on each occasion. I have since bought a booster pack for them in case of further breakdowns.

On inquiring from the Toyota main dealer, I was told that this is a regular occurrence with their Hybrids in winter, and that they should be brought for a good drive every week to keep the 12 Volt battery topped up. Unfortunately this isn't always feasible with older drivers. Surely Toyota should put in better batteries in their cars to avoid this battery failure in the future.

I am just wondering if this issue is just with Toyota Hybrids or is it a similar problem with other makes of car, as my mother is thinking of trading her Yaris in, and is reluctant go with Toyota next time.

Eoinbmw · 07-01-2026 02:34PM

Same with modern fords hybrid petrols as we have experienced!

We trickle charge the battery couple of times a year pain but it works!

Busman Paddy Lasty · 07-01-2026 02:39PM

CHR died several times on a family member. Seems to be a quirk of them.

User1998 · 07-01-2026 02:45PM

If it's not feasible for them to adequately drive their cars and thus charge the batteries then maybe they should consider sharing a car or buying non hybrids cars. Can't really blame the manufacturer if they aren't driving their cars enough to charge the batteries

o1s1n · 07-01-2026 02:51PM

Not sure if it's possible to use with hybrids but I installed one of these on my standard petrol car battery a few months ago (it would drain after two weeks of not driving due to a parasitic draw I couldn't figure out) and totally solved the issue.

https://www.amazon.ie/Worries-Batteries-Effective-Vehicle-Anytime/dp/B0FFG9JSY8/ref%3Dasc_df_B0FFG9JSY8?mcid=3d6d142ee7ab3d94b0bd95fd6e129cad&tag=ieshopgode-21&linkCode=df0&hvadid=743418918455&hvpos=&hvnetw=g&hvrand=1013297747808268557&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-2444584277667&psc=1&language=en_IE&gad_source=1

You just screw out the green screw and it disconnects the battery. Screw it back it and it reconnects it.

Fairly rudimentary type fix and it does mean you've to pop the bonnet before you go for a drive to turn the screw, but if you're driving less than once a week then totally managable. It has been for me so far anyway. Also doubles as an anti theft device.

TigerTim · 07-01-2026 03:45PM

https://www.boards.ie/discussion/comment/124125706#Comment_124125706

I do similar on an older classic car. Only downside is the radio loses it's code when power is cut.

T.

almostover · 07-01-2026 03:58PM

https://www.boards.ie/discussion/2058430790/what-the-car-dealers-don-039-t-tell-you-when-buying-a-new-toyota-hybrid-car-and-the-12-volt-battery

I have a Lexus Hybrid (same as Toyota) car that is 12.5 years old and it's on its original 12V battery. I charged it once ever, not because the car failed to start but because I voltage tested the battery and it was on the lower side, around 12.4-12.5V. The car has never failed to start.

The 12V battery on any car can discharge if not driven regularly, especially in the current cold weather. It's not a phenomenon exclusive to Hybrid cars.

I've probably jinxed myself with this post but the Toyota Hybrid systems are the best on the market and this isn't really an issue with them. Batteries discharge if not used and recharged by use.

I recently replaced the original 12V battery in my wife's 8 year old Mazda CX-5 which has a conventional petrol engine. The stop/start system wasn't working which is always a tell tale sign of a discharged battery.

FYI most decent 12V batteries are warranted for 3 years, some Yuasa batteries for 5 years. Anything more you get out of them is a bonus.

bazz26 · 07-01-2026 04:29PM

I think the problem here is the lack of use the car is getting. Battery cells discharge when not in use also.

odyssey06 · 07-01-2026 04:48PM

https://www.boards.ie/discussion/comment/124125706#Comment_124125706

The 12V battery in the Yaris is underneath the passenger seat behind the driver. Not as easy to get at as your standard main battery.

odyssey06 · 07-01-2026 04:51PM

OP, have you tried 'Ready Mode' as per below advice?
Turn off radio, AC etc.
This might be more convenient than long drive?

Hybrid car owners should switch on ‘Ready Mode’ for approximately 30 minutes every 15 to 20 days to keep the battery topped up.
- It’s important to note, that for Hybrid users the engine may not kick-in or omit any sound, however their dashboard’s ‘Ready Lamp’ will be illuminated when ‘Ready Mode’ is active.
- It is important to uphold car safety when in ‘Ready Mode’ and ensure all lights are turned off, the car’s position is secure with the brake on, and no passengers are in the vehicle.

https://www.toyota.ie/company/news/2020/maintaining-battery-life

User1998 · 07-01-2026 05:11PM

Hybrid 12v batteries are tiny in fairness. They definitely discharge quicker than petrol/diesel cars

iBaxter · 08-01-2026 12:19AM

Thanks folks for your replies, it seems to be fact that the Hybrid cars are only being used for short journeys, however its strange that they never had this problem before with regular manual petrol cars, which maybe don't drain the batteries as quickly. It also seems to be a general problem with other brands of Hybrids such as Fords as mentioned above.

John.G · 08-01-2026 08:30AM

https://www.boards.ie/discussion/comment/124125956#Comment_124125956

The OP's 10kms/day, (each) EVERY DAY, should be more than adequate IMO to keep any battery poperly charged.

pauly58 · 08-01-2026 09:28AM

https://www.boards.ie/discussion/comment/124126173#Comment_124126173

You are right, we had a Honda Jazz hybrid, the battery was the same size as a motorcycle battery & let us down, we were using it for decent size journeys.

Eoinbmw · 08-01-2026 09:40AM

https://www.boards.ie/discussion/comment/124128110#Comment_124128110

Its not in our 2025 ford! But strangely previous non hybrid fords were fine last one being 2023.

Captain Chaos · 08-01-2026 10:34AM

I had the same issue in December with our first Hybrid. A 2018 Yaris Hybrid failed to start with a flat battery only 2 months after purchase. The battery failure also effected the build in pre collision camera causing a software glith that made the car thing it was in a collision and would not allow the engine to start or even start in EV mode with the battery recharged.

It has really knocked my confidence and my wife's with Toyota Hybrids and Toyotas in general. I've had 3 Ford petrols over the past 16 years an not an issue with them ever. I am told Toyotas are "bullet proof" and nothing goes wrong with them and was told that their Hybrid systems are the best out there. Even the build quality of the Toyotas are not at Ford standards in materials, sound and weather proofing from my experience in like for like specs.

User1998 · 08-01-2026 10:39AM

https://www.boards.ie/discussion/comment/124128182#Comment_124128182

The plus side is that they only cost like €60 to replace vs €150 for a bigger stop/start battery

pale rider · 08-01-2026 10:46AM

I bought a booster to use if it even happens, seems daft in a new car but necessary in a pinch to keep moving, inexpensive as well.

Lots of hybrid drivers have been caught out with this

GPoint · 08-01-2026 01:00PM

Issue with all new-ish cars batteries is that target SOC is set very low and the car will not charge battery enough even if driven.
All in the sake of saving fuel and environment. Had this problem in my ford focus and updated ECU to charge battery to 100% but even that did not help much.
Older cars could run on original batteries for up to 10 years.

Flinty997 · 08-01-2026 01:14PM

I bought a bigger battery with a higher dwell time in the cold for an older car that we don't use much.

John.G · 08-01-2026 04:47PM

https://www.boards.ie/discussion/comment/124128731#Comment_124128731

On a Hybrid, do both the "starting" battery and the main battery determine when the engine cuts in to recharge either? What does this small battery supply power to?.

Field east · 08-01-2026 06:18PM

the following points may be of help to understand what is happening:-

(1) If the charge being taken out of the battery is more than the charge going into the battery - via dynamo/ alternator- then a point is reached wherein there is not sufficient power/ charge -volts- in the battery to start the car

(2) starting a car- and especially if it takes a while to start- takes a significant amount of power from the battery. ‘They say’ that one would need to drive 20km + in order to put back into the battery - from the charging system- then a point power that was used to start the car

(3) There is probably more draw on the battery’s power in the wintertime because the heater is used , headlights used more and the car is more efficient to run - battery power consumption wise - during the summer because the ambient temp is higher

(4) another draw on the battery’s power in is, apparently, moisture - especiallly during wintertime when the air is cold and saturated with moisture. The moisture acts as a kind of conduit between the two battery poles thus causing charge leakage.

I AM OPEN TO BE CONTRADICTED ON ANY OF THE ABOVE

So , in summary, the ‘trick’ is , to be aware of the undesirability of doing short journeys all the time and keep items drawing energy from the battery at a minimum eg heater, air conditioner

I had a ‘friend’ who would buy a new car and he was back to the main dealer with a flat battery problem . She used to use the car to drive to mass only twice a week at a half mile down the road - so a constant draw on the battery and with little or on charge being put back into it

tabby aspreme · 08-01-2026 07:07PM

My OH has been driving Toyota hybrids for about 7 years now and has been caught a few times with the battery, each time it was a result of the ignition/ACC switched on with lights or heater running, when everything was switched off for about 15 minutes the battery recovered enough to start the car, the battery in the first car had to be replaced after 7 years, new battery from Toyota was 180, motor factors wanted 250, it's a leak proof AGM battery so slightly different to most as its fitted within the cabin or boot of the car.

kirving · 08-01-2026 10:55PM

Wasn't there an almost identical post to this last year?

Some of it has to do with it being a newer car, not just because it's a hybrid. They're be running telematics, more complicated (anti-relay) keyless entry, internal alarm systems, etc.

I get an email when my car battery is low, which is ironic because the telematic service that does that, is partly resposible for draining the battery in the first place.

https://www.boards.ie/discussion/comment/124129944#Comment_124129944

Mostly correct, except for Point 2. Modern (20+ years old by now) smart charging systems will charge the battery more aggressively at the beginning of the journey, and hybrids often do away with an alternator altogether, and charge the 12V battery via the HV battery using a DC-DV convertor.

Lenar3556 · 08-01-2026 11:42PM

https://www.boards.ie/discussion/comment/124125683#Comment_124125683

I think Toyota can do better than that. There are relatively simple engineering solutions to solve or at least mitigate the problem.

Montage of Feck · 09-01-2026 12:09AM

Most modern cars with stop start are quite hard on batteries, its not unique to Toyota.

User1998 · 09-01-2026 12:13AM

https://www.boards.ie/discussion/comment/124131374#Comment_124131374

Hybrids don't use stop/start batteries

Damien360 · 09-01-2026 12:48AM

the 12V dying after one year is a surprise but not the 3 years on the Yaris. We had a 07 avensis doing town mileage only and over its 10 year life with us we replaced it at least 3 times. So that’s pre hybrid stuff. Our 5 year old CHR has already had one replaced and was caught during yearly service. Genuine one was around €100 I think so not a ball buster.

Lenar3556 · 09-01-2026 12:51AM

https://www.boards.ie/discussion/comment/124131374#Comment_124131374

Are they?
They use a different technology which is suited to constant stop start - the lifespan is generally acceptable.

The issue on toyota hybrids is a separate one, whereby the particularly small 12V battery doesn’t receive sufficient charge from the hybrid system depending on the manner and nature of driving. It can become discharged and the car won’t start.

yagan · 09-01-2026 01:21AM

I really do believe Toyota should state upfront that the newer hybrids need regular spins to avoid battery drain.

I had the exact same issue with an elderly relative who swore by toyotas since the 80s, but ended up needing a jump almost monthly for her hybrid Corolla.

She might do only 20 minutes of driving over week to the shop for bread, ham and milk but it wasn't enough.

Trying to explain to her that it's her fault for not driving it enough is an insult. Her driving habits hadn't been an issue on the pre hybrid so this very much is a brand betrayal.

I guess toyota haven't been sued for not highlighting the need to change driving duration because the people this issue affects most are so brand loyal.

John.G · 09-01-2026 08:49AM

Starting a car takes a very significant amount of power but the energy required is the sqroot of nothing, most cars will start with a 2 to 3 sec crank, even allowing a 4 sec crank at say 400A will only deplete the battery by 400*4/3600, 0.45AH, my smart alternator will charge at its full charging voltage of 14.9V for around a minute before dropping back to 13.6V every time immediately after starting even when the battery is at its full 85% SOC, it obviously won't charge at its full output of say 90A, I've seen mine charging at around 14/16A for that minute or so which will restore most if not all of the starting drain, my (petrol) Polo starts in 2/3 secs and probably only requires < 300 cranking amps so ~ 0.25AH/start.

One would think that all hybrid batteries (12V) are recharged from the main battery bank via a DC to DC converter or whatever so would expect it to be fully charged at all times no matter how short the trip, so is parasitic drain the main culprit?. All my cars had a parasitic loss of 35/40mA, apart from one, a 2005 Polo 9N still in the family which had/has a loss of 80/90mA, yet never failed to start, original battery replaced after 11/12 years (precautionery) and replacement battery still there after 8 years.

What the car dealers don't tell you when buying a new Toyota Hybrid car, and the 12 Volt battery.

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