Hi everyone,

I wanted to share a concerning experience with my brand-new 2025 Lexus UX300h hybrid, particularly regarding its 12V battery performance in cold weather conditions.

Background:

• The car has only 25 km on the odometer.
• After sitting for just one week in my insulated garage, the 12V battery completely died.
• I drove 30 km two days ago, but a recent voltage check showed 11.6V, which seems low.

Key Issues:

• The 12V battery's Cold Cranking Amps (CCA) rating is 285A, which feels inadequate for winter conditions, especially in Canada.
• The local dealership has been deflecting my questions about this issue, attributing the problem to my driving habits (short trips, infrequent use).
• Lexus recommends using a battery minder (trickle charger) if the car isn’t driven long distances, but this was never mentioned during the sales process.

Concerns:

• The lack of transparency from the dealership is disappointing. As a customer, I believe I should have been informed about the 12V battery’s limitations and any additional maintenance requirements.
• Hybrid owners in colder climates face real risks if their vehicles become unreliable in winter.
• Other manufacturers, like Hyundai, have addressed this issue by including features like a 12V battery reset button, which would be helpful in these situations.

I’ve contacted Lexus Canada and filed a complaint with Transport Canada to highlight this issue as a potential safety concern.

Has anyone else experienced similar problems with their Lexus hybrid in cold weather? I’d appreciate any advice or suggestions for handling this.

Looking forward to hearing from you all!

 

I was buying used Ux300h 2025 from Calgary dealership and same thing happen. During car introduction 12V battery died. It was very embarrassing for them. Battery was replaced right away, but the problem with UXes exist.

 

Thanks for sharing your experience! I think it’s a major design flaw to use a light-duty 12V battery. I'm thinking about filing a complaint with Transport Canada about it.

I stumbled upon this YouTube video that says this is quite a common thing in Canada. Check it out:

 

The Lexus UX300h in the EU uses a Yuasa 285A SLI base battery. This battery is sensitive to incomplete charging.

You never know how much energy the battery actually contains, and repeated discharging will quickly damage it and cause a loss of its total capacity. If this happens, it doesn't matter if you drive 200 km a day... the battery will never charge to the required capacity. The charging system is floating and charges the battery between 13.4 and 14.4 V. When the system determines that the battery is charged and warmed up to the ideal state, the charging drops to 12.8 V. However, it may happen that you park the car again in an undercharged state and the battery will discharge again in 2-3 days. This will repeatedly destroy the basic battery. One option is to replace the battery with a higher-grade EFB battery for the start-stop system, but still compatible with UX with a larger capacity, e.g., Yuasa series 7000 and BT battery monitor, and try to keep the new battery charged within the SoC range of 80-100%.

Do not use the car in ACC mode, only in READY mode, and after driving, recharge the car battery in the P position for at least 15+ minutes.

 

My LEXUS 2023 RX350h had 12V battery issues many times, specially in Winter. It drained and could not access the vehicle without manual key. Had to call LEXUS Roadside Assistance several times.

 

Your 12v battery operates some accessories plus sends a signal to the hybrid system to start the car so it's part of the process but doesn't crank anything if that's what you were thinking. Sales people are not going to tell you anything negative about a vehicle you're about to purchase so it sucks for you but you are not alone...it happens to ice vehicles as well.

 

yes i have same car every time minus 28 no start its because there battery SPEC. is 285 CCA way to small one flat bed and 3 boost all Lexus warranty you buy a 480 CCA battery because Lexus wont help you or add 2 amp battery charger