Generally, there are two issues your battery can run into. The first is if it’s too weak to have enough of a charge to start your engine. When this occurs, you can usually tell when you try to start the car and it either takes longer to turn over or doesn’t start.
If it takes longer and seems to struggle with starting, your battery is weak. If the car won’t start at all, your battery is likely dead.
The second issue is if your battery is damaged. You can usually see any damage by looking at it. If there’s any signs of corrosion around the connectors or visible cracks in the battery, you’ll be able to spot them right away.
If there’s a serious crack and leak, you may even smell it while you’re sitting in the driver’s seat. It’ll give off a pungent sulfur smell.
In many cases, you can clean residue off the battery, but if there’s a crack, it’ll have to be replaced.