Good battery test

[F150]

I went to Sam's Club to get a new battery, because mine left me stranded the other night. they tested and said the battery tested good but showed 8.7V on the crank part of the test . is my starter going bad or battery? 2023 Mazda CX50 2.5S ???

 

[DCDG]

I don't know about their test equipment under 9v on crank is definitely trouble zone and sign of a failing cell or high resistance. And it may read 12v just sitting there with no demand on it.

 

[Kira]

How old is the battery?
Has the 2023 Mazda been used on the highway or stopped and started 40 times a day?
Has it ever been part of a maintenance (charging) schedule?
The first day of searing Florida heat may be "the test" for it.

 

[F150]

Battery is 3.5 years old, short triped but used everyday, I'm thinking Battery, but coule it be starter?

 

[The_Jeff]

Starters do "drag" but it's unexpected on a 3 year old car.

Those that do "drag" crank slowly even when jumped with a running car. And they take tons of amps and cause lots of voltage drop even with healthy batteries.

OE batteries can be like OE tires; good enough to sell the car. Plus you don't know what abuse (non-use) the car suffered between the factory and final delivery.

 

[f355spider]

Below 9.5vt to 9.6vt is usually considered a fail on the crank test. The person maybe interpeting the results incorrectly. I would try another store, or another time of day.