A previous post mentioned battery and for a 2018 Ford with a big AGM that is likely, yet will cost much more than $100. There is a LOT of parasitic draw from so many different places on these vehicles nowadays.
My first awareness of this issue and reading about probable battery failure was with my wife's RX350. Normally you can walk up to the locked car with a fob in your pocket or purse and just touch the door handle to unlock. When that started becoming intermittent a dying battery is said to be a common cause. Since her battery was 5 years old I just went down to Costco and bought one for about $100. No more issues with unlocking.
My Expedition (F-150 from the dash forward) has much better working door handle unlocking ability, and is 2 years old. When I had a dead battery recently I trickle charged it overnight read a lot of info on the Expedtion Forum and see that Ford has been having to warranty some of these big AGM batteries, which are covered under the bumper to bumper for 36K/3 years. Out of warranty the average cost to have a Ford dealer replace it is about $275. Costco doesn't have these yet. You can buy the Ford Motorcraft battery from Rock Auto for $170.
https://www.rockauto.com/en/parts/mo...0,battery,2476
With my battery issue I went to Autozone the next day after charging and their tester showed 78% charged and said "Bad Battery". Thought I was going to get a free one from the Ford Dealer, yet they called me up and said they found a loose ground and wondered if I had serviced the battery. It was no charge though and a month later it is still fine. They do have much better testing equipment and is a reminder that you can't always believe what average testers and OBDII diagnostic results are.
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