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
Just a thought! maybe if the car is monitoring the charge of the battery ! and sending this information to Toyota, This will no doubt be draining the Battery.
Your reply would be much appreciated!
Morning Neil,
Thanks for sharing your thoughts. There are many electrical demands on modern cars which contribute to the draining of the 12v battery, communicating with the MyToyota app would be one of those, yes.
Thank you.
These comments are really helpful. Driven Toyota hybrids as company cars for years without a single issue. I buy one for myself and now I have low battery alerts through the app and needed a mechanic call-out to get me started. I’ve read the tips and will follow them but 1) Why don’t they tell you short trips are a bad thing when you buy the car? 2) why do they want £65 from me to check my battery (4 year old car) and £300 to replace it? Really unhappy to spend £27,000 on the most reliable brand in the world to have to play Russian Roulette at being stranded everywhere I go. Was considering changing our second car for a used Yaris hybrid. Not much chance of that now!
Morning Andrew,
Thanks for getting in touch. As with any vehicle, 12v battery performance can be influenced by a range of factors, including vehicle usage patterns, journey types, environmental conditions, electrical demands placed on the vehicle and battery age. Vehicle usage is only one factor among many. With the wide choice of powertrains available today, our centre network understand the importance of discussing a customer’s driving patterns and expected vehicle usage before recommending a particular vehicle. We will continue to work with our centres on providing clear, empathetic and customer-focused communications to ensure customers feel fully supported when raising concerns.
We’re sorry you’ve experienced some problems with the 12v battery, we’d encourage booking your car in to your local Toyota Centre for a free battery quality inspection.
Thank you.
I spent over 30k on a new Yaris Cross, the dealer knew I was no longer doing a regular high mileage but never said anything about this needing to use the car every 14 days. I go on holiday and come back to the low battery warnings. I am very disappointed and now don’t trust either the vehicle or Toyota.
Good morning,
We’re sorry to hear you’ve lost faith in both your Yaris Cross Hybrid and Toyota.
If you’re concerned about the 12v battery in your car, we’d recommend getting in touch with your local Toyota Centre for an inspection.
Thank you.
It is so annoying that these battery drain problems are so common. This is obviously a design problem that Toyota refuse to accept. When I first had the problem the battery was tested and declared ok, but the technician admitted that some cars were now fitted with larger capacity batteries. If you buy a diesel car now you are told to make sure you drive it enough to clean the DPF filter, otherwise stick with petrol. Why are you not given the same warning when buying a Toyota, whose models seem to suffer so much more than other makes with this problem?
Why buy a car that needs to be driven needlessly just to keep it working properly. I enjoy driving my Corolla,(2.5 years old)but am afraid I will have to DUMP it soon as I am fed up having to charge it up twice a week now just to be confident that it will start when I need it. In the meantime I have purchased a jump starter, which I keep in the car, also a trickle charger and a battery tester!!!! These items should be given out to every Toyota owner free of charge.
Good morning,
Thanks for sharing your thoughts. With the wide choice of powertrains available today, our centres understand the importance of discussing a customer’s driving patterns and expected vehicle usage before recommending a particular vehicle. Toyota and Lexus have sold hybrid vehicles in the UK for more than 25 years, with over one million hybrid vehicles sold. We do not specify a minimum annual mileage requirement for our hybrid vehicles. As with any vehicle, 12v battery condition and lifespan are influenced by a variety of factors including driving patterns, journey types, vehicle usage, environmental conditions and battery age.
Battery performance considerations and customer guidance on maintaining battery health are common across the automotive industry and are not unique to Toyota or Lexus. We remain committed to ensuring the information and advice provided to customers is accurate, up to date and supports informed purchasing decisions.
Thank you.
I have been reading the numerous comments relating to 12v batteries with increasing alarm. I now I wish I hadn’t bought a 2023 Yaris Cross last October. I live in constant fear of having a flat battery or door locking issue. I am an 80 year old widow and do mostly local trips to the supermarket or leisure centre. Occasional I have a long trip but probably not more than 3000 miles per year.
In the winter it may be left for several days. If I go on holiday I will be worrying about it.
I do not have an outside socket and park in the shade so charging is not realistic. Why should I need to do that or sit outside while running the engine for 30 minutes. It is ridiculous.
My previous cars were a Nissan Juke and a Mini Cooper. I never had worries like this. I wonder, if I sell it , how much will I lose. It clearly should not be recommended to people in my position
It is a lovely car but now totally spoilt by worries.
Morning Carolyn,
Thank you for getting in touch. We’re sorry to hear you’ve lost faith in your Yaris Cross Hybrid and for the concern and worry this causes.
We’d recommend getting in touch with your local Toyota Centre to arrange a free battery quality inspection.
Thank you.
On the 3rd Jan 27 I will shortly be taking a 45 day cruise and expect to leave my 22 plate Yaris Cross at an outside carpark.
I will be taking a 4/5 hour drive to get to the ship – what if any precautions/preparations do I need to take to ensure my car will start and get me back on the 4/5 hour trip?
Morning Robert,
Thanks for your question. That cruise sounds very exciting and we wouldn’t want you worrying so a battery maintenance device may be a suitable recommendation. Your local Toyota Centre are on hand to discuss options available.
Thank you.