2018 Ecoboost battery problems..?

[vetonater]

so just to give you guys a back story, randomly one time last year I went to start my ‘18EB one day and the battery was dead, I took it to have the battery tested and they said it was perfectly healthy..
Last week I turned my car off to put gas in it, and it would not start back. The voltage from the dashboard was ~9v, I let the car sit and it somehow got to about 10v and it eventually started.. after maybe 5 failed attempts of waiting, now whenever I turn my car off the battery immediately drops to 10v, and I Will immediately start it but is very slow at turning over, I’m worried if I let my car sit over night I will come back to a completely dead battery. The only thing I’ve changed is I have a 93 octane tune, and I just flashed it back to stock prior to these things happening, coincidence or related? Thank you for the input!

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[Reddirocket27]

Tbh, I replace batteries every 3 years, no matter what. A single loose cell can cause a hard (or no) start. Batteries are incredibly cheap nowadays.

 

[NightmareMoon]

Ya, stock (and most aftermarket) batteries older than 3 years are on borrowed time. Just get a new one, its far more likely that the battery is just at the end of its natural life than anything tune related.

its not uncommon for a dying batter to pass the test and then fail it the very next day. BTDT. Now I also replace batteries at 3 years -replacing them before they fail is a lot less annoying than it being a surprise.

 

[vetonater]

Any different batteries I should look into getting? Or another stock one

 

[ORRadtech]

I don't know who tested your battery but they were likely incompetent.

Without competent testing by you or someone qualified to verify Icouldn't say for 100% but I'd be willing to bet you need a new battery.
My '18 EB is 1 year into its second battery.
Newer cars that are heavy with technology are very hard on batteries.

 

[vetonater]

Thank you for the input, I was thinking it was the battery as well!

 

[Cobra Jet]

Check battery terminals for corrosion, make sure terminals are lean at the posts and inside the harness terminal rings. Also check for any poor/loose grounds at inner fenders near radiator support.

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