It's not very scientific but every time I started my wife's 2018 Subaru Forester still using its stock 6-year-old battery, I could hear the starter motor wasn't quite as "energetic" as I remembered when the vehicle was younger. Though the Forester still started, it had just a slight hesitation. I bought the TOPDON BT50 12 volt automotive battery tester and its "Battery Test" said the battery was good. However, when I used the BT50's "Crank Test", it gave a different result. Check out the full video for more details by clicking the link at the bottom of this shorts video.

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