Battery problems after 4-5 months

We purchased the hybrid Nautilus in July 2024. Everything was great until late November. We noticed our gas mileage was lower than expected on a long trip over Thanksgiving. We chalked it up to cold weather, but it continued to decline and by Christmas I was experiencing those messages saying "features going into deep sleep to conserve battery." Plus, my gas mileage is low and very little electric miles. So I took a few drives of over 30 miles. It did not help and I finally emailed my sales rep who referred me to the service coordinator. I was told my battery was down to 30% and to bring it in for a charge up and get a trickle charger to use a few times a week. That was 7 days ago. I wasn't happy- we bought this car to AVOID having a plug in hybrid! I assumed it was more cold weather related. Since the full charge I've had a few longer distance drives and I used the trickle charger once (was plugged in for 12 hours). I got the battery message again this morning,and my gas mileage has declined every day the past week. WTF? Anyone else with this issue? Should I demand new batteries? Start Lemon Law process? I love the vehicle in every other way...

Lincoln has issued software updates (CSP 24P14 and 24P08) that address similar battery drain problems. It might be worth asking your dealer to confirm if your Nautilus is up to date with these fixes. Hopefully, this will get everything back to normal without needing a battery replacement.

Update - They replaced our 12v battery AND found that the amplifier was faulty and causing unnecessary drain on the battery 24/7. Amp was replaced. These 2 changes fixed all the features that were constantly going into deep sleep and the lag time for the computer to start up, but it did NOT fully fix our MPG issues. I'm averaging only 22ish MPG vs the 30-34 we had for the first few months after purchase and what is advertised. I've been tracking our MPG and electric miles used since then - my phone is FULL of pictures of the trip tracker, LOL. I have a call out to the sales manager again letting them know that we are still not happy about this and we need to investigate further or we will be pursuing the lemon law in our state (which is fairly strong and in our favor). My spouse has postulated that the lithium battery may have been damaged during the months of 12v battery issues related to the amp. This is just a guess...and of course, the dealership wasn't willing to replace it when they replaced the 12v, I'm sure because of the cost. Regardless, they have 1 more day to respond to our messages or we will take our issue to the manager, or possibly the dealership owner, with whom my spouse is professionally acquainted through a local business owner association.

**Also, all the software has been updated.