The 12-volt auxiliary battery is the unsung hero of your car’s electrical system. This fundamental component provides the sole source of power for all low-voltage electrical features, from the lights and starter motor (where fitted) to climate control and audio systems. Modern vehicles contain much more technology than even those of a decade ago. Yet despite having to provide the energy for these increased demands, all the 12V battery requires to maintain a virtuous electrical cycle is to be effectively recharged by the powertrain.
This method of expending and reinstating electrical energy has been used in vehicles for more than 100 years. It is extremely reliable, and in the majority of circumstances entirely self-sustaining. However, a little knowledge and the following handful of tips will help owners support the health of their car’s 12V battery.
What are the primary causes of 12V battery issues?
Most problems occur when the 12V battery has not been given the chance to properly recharge. It takes a little time to reinstate the charge that was expended from the battery at start-up – more if there are lots of additional electrical systems in use at the same time. Consistently short journeys are therefore likely to slowly deplete the battery’s reserves.
Cold weather is also tough on the battery. Low temperatures slow the chemical reactions inside the battery cells, which make it harder to start the engine and easier for the battery to lose charge. In addition, cold weather usually means greater reliance on electrical systems for heating, ventilation and lighting – all of which draw power from the 12V battery.
Recommendations for maintaining 12V battery health
1) Frequent use. Where possible, aim to take your car on a 30-minute journey at least once a week. If this is not possible or you plan not to use the car for a prolonged period, use a quality battery maintainer (also called a trickle charger) to keep the charge level topped up. Toyota Centre staff will be able to advise on whether a mains- or solar-powered option is the best for your circumstances.
2) Combine trips. Constant short trips will get your battery down, so try reducing their frequency by combining errands. And if these journeys require a couple of short stops, don’t worry too much. Less battery energy is required to start an already warm engine; and similarly, less energy is required to maintain the climate of an already warm cabin.
3) Avoid wasting energy. Remember that if the powertrain is not active it is not charging the battery. In that case, electrical accessories such as lights, ventilation and the audio system will all nibble away at the level of charge. So make it a habit to switch off these accessories before turning off the engine. Not only will this preserve the charge but it will stop the battery having to power the systems back up at the same time as starting the powertrain.
4) Check the battery’s condition. Regularly inspect your battery for corrosion around the terminals and ensure the cables attached to them are tight and clean. Your local Toyota Centre will check these connections as part of your car’s regular service programme, but will also be happy to offer advice outside of this schedule.
What about electrified vehicles – do they have a 12V battery?
Yes, they do. Hybrid and full electric vehicles are equipped with two batteries: a 12V auxiliary battery for the same low-voltage electrical features as any other car, and a much larger traction battery that powers the electric motor/s to drive the vehicle.
In both vehicle types, it is important to note that the 12V battery is only trickle-charged when the powertrain is turned on – also known as READY mode. We therefore recommend that drivers use READY mode whenever they are inside the vehicle using electrical features, such as listening to the radio while waiting to collect a family member.
What to do if you have a problem
Owners who follow the recommendations listed above are unlikely to experience a problem with their car’s 12V battery. However, if an issue does arise, be assured that expert help is never more than a phone call away.
Breakdown cover arranged through Toyota Roadside Assistance offers year-round support, 24 hours a day. Delivered in partnership with The AA, the UK’s number one provider, this breakdown cover includes jump starts, towing and emergency roadside assistance. In addition, the nationwide network of Toyota Centres is also available for advice or assistance.
FAQs:
How can I make sure the 12V battery is in good condition after it has been parked for an extended period of time?
Consider using a quality battery maintainer to keep the charge level topped up. Toyota Centre staff will be able to advise on whether a mains- or solar-powered option is the best for your circumstances.
How do I put my vehicle in READY mode?
READY mode only applies to full hybrid or full electric vehicles. First, ensure the transmission is in PARK and that the handbrake or e-brake is engaged. Then apply the foot brake and press the vehicle’s START button. Green READY lettering (see image below) will illuminate on the dashboard to confirm that this mode is now active.
NB: Remember that if the powertrain is not active, low-voltage accessories like the lights, ventilation and audio system will all draw power from the 12V battery.
Will using a dash cam affect the 12V battery?
Toyota approved accessory dash cams should not cause any drain on the 12V battery when both the vehicle and dash cam are switched off (and parked). However, when the dash cam is active, ensure the powertrain is either running or the vehicle is in READY (not ACCESSORY) mode to prevent draining the 12V battery.
Does using connected services on the MyToyota app drain the 12V battery’s power?
Yes, a very small amount of power is drawn from the 12V battery when owners use Toyota Connected Services. Refreshing the vehicle status in the MyToyota app can wake the vehicle, so make sure to follow our battery maintenance recommendations if you regularly refresh your vehicle’s status.
What should I do if I’ve received a ‘Starter Battery Low Charge’ alert from the MyToyota app?
The MyToyota app does not directly monitor the charge level in the 12V battery (starter battery) but is programmed to predict its health and alert owners as a result of other factors, such as the infrequency of the vehicle’s use. The alert is therefore a calculated suggestion that the battery would benefit from the vehicle being driven for at least 30 minutes.
NB: Notifications can take 24 hours to clear from the app after the vehicle has been driven.
Is the 12V battery covered by Toyota’s manufacturer warranty?
Yes, the 12V battery is covered by our manufacturer warranty for up to three years or 60,000 miles, whichever comes first. This includes any failure caused by defects in manufacturing or assembly.
NB: The 12V battery is not covered under the following warranty products: Toyota Battery Care, Toyota Hybrid Battery Cover, Service Activated Warranty or Approved Used Warranty.
Useful links:
Winter driving tips
How to get the most out of a hybrid electric vehicle
Having driven various makes of Toyota vehicles I have never had trouble until now with this ridiculous situation of the 12v battery not being sufficient to ensure the car is available when I need it. Having to purchase additional equipment or leave it running is a non sensical solution when Toyota should be arranging a permanent solution for their customers. Do not tell me to refer to the dealership as they can’t even recommend a good trickle charger and state they are only saying what Toyota are telling them to say yet I see in your comments you are saying see your dealer for help. Going round in circles is not a good look for a once reliable company.
I had a Hyundai Kona hybrid
The car wouldn’t start – flat battery but when I contacted AA they talked me through a process to use the main battery to bypass the starter battery and so started the car.
Why do Toyota not have a similar system?
I am constantly getting low battery notifications as I am doing short distance runs – battery checked by Toyota on Friday- all ok but today Tuesday received a notification, very annoying
I agree totally with the previous comments of E. Richards.
The answer is not to request visiting your local Toyota dealer but come up with a permanent solution.
A temporary solution would be for Toyota to fit a better quality and higher AmpHour rated battery to all affected models.
I purchased my new C-HR Premiere Edition HEV in March 2025 and all was fine until October 2025 when I started getting the infamous Battery alert from the App.
After having it checked out by my local Dealer without a solution, I raised the issue with Toyota Customer Services and after 3 months of pestering and many more App alerts they finally agreed to replace my battery under warranty in January 2026.
All has been fine until yesterday (19th October) when once again I received the App alert so here we go again.
Like many others, I have owned Toyota’s for many years and it’s worth mentioning that during the previous 4 years of owning a C-HR Orange Edition HEV, I never had this issue once!
So come on Toyota, stop hiding behind the issue and put it right before all your previously loyal customers take their business elsewhere.
I thought I had this issue fixed, but here I am about 9 months later getting emails from Toyota saying my starter battery requires charging…and that was after two 30 minute trips yesterday. I bought a Toyota for reliability and the extended warranty when you maintain the servicing…but this has been the least reliable vehicle I have ever owned and it is less than 2 years old. Disappointed doesn’t come close to describing my feelings. You pay for what you think is quality, and get what are apparently known battery issues thrown in for free. Come on Toyota – you have been in hybrid technology for long enough to not be knowingly selling cars with this problem.
I do not understand the position of Toyota importers in the EU regarding these 12V battery issues. Across various countries, Toyota denies the existence of the problem, merely providing dealerships with scripted talking points to use with dissatisfied customers—all without offering any genuine, long-term solution. The manufacturer has compromised the reliability of its hybrid vehicles through a completely nonsensical approach to 12V battery management, failing to account for the realities of how a battery functions. Furthermore, they use low-end, maintenance-required batteries—a type of component no longer found in any other modern vehicle. The Hyundai/Kia group has implemented a solution for this same issue; at Toyota, there is NOTHING!!!
I totally agree!!!
My wife & I have had 5 Toyotas, CHR & Yarris Cross models, all from new. All of them have had the same problem if they aren used constantly.
We have just been on a 3 week holiday & on the second week we got a message from the Toyotal app saying the battery in my wife’s Yaris Cross was low, got home & couldnt get into the car, completly dead, battery was at 1.8 volts.
Toyotal cars are great but until Toyota fixes this problem they will lose customers.
Its not hard to fix, put a software check to limit the parasetic drain on the battery &/or fit a bigger battery. Why make a system that is so sensitive to low battery voltage?
Rant over – Paul
Shocking! I totally regret buying this 2026 plate Toyota hybrid. Being alerted the battery is low….I’ve never had this problem before. I should not have to drive around using petrol, traffic etc to recharge the ridiculous 12v battery! Awful car.
Good morning,
We are sorry to hear that you are experiencing issues with your vehicle.
We would recommend visiting your local Toyota Centre and having the vehicle inspected. Our trained technicians will be able to assess the issue and provide further advice on maintaining your vehicle’s 12V battery.
Thank you.
I wish you wouldn’t refer to a battery maintainer or smart charger as a ‘trickle charger’. To us old school types (not untypical Toyota buyers) a trickle charger is just a low current charger that can be left to charge a battery slowly. If left connected indefinitely it will dry up the battery.
I have a 2024 C-HR that was sending My toyota app alarms about low voltage in my 12 volt battery, after 3 visits to my toyota and numerous battery checks the technicians found that the dash cams were connected to the wrong terminal, so I thought problem solved.
Since then the alarm has come in 5 times, 3 times a day after a 400 mile trip!! What is a 30 minute trip going to do that a 6 hour trip at 70mph can’t do?
Why does the alarm not show on the instrument display?
Also the Instrument display (speedo and tacho)turns to a yellow background and the lighting in the doors turn yellow, it turns back to blue after a couple of miles, I have told my local service centre about it but they know nothing about it and have not heard about this happening before? I feel it is a warning about something but who knows what? Maybe Toyota can enlighten me because the local service centre can’t!A|
Morning Alan, thanks for getting in touch.
The low battery warning which was introduced in April 2025 to our cars with connected services is not a live reading so can take time to clear, even after completing a long journey. For more details on the MyToyota app, please visit: https://www.toyota.co.uk/owners/connectivity
If we can take your VIN please, we’ll look into your second question regarding the coloured backgrounds.
Thank you.