Battery or Alternator? How to Tell the Difference | Broward FL

Is It the Battery or the Alternator?

These two get confused constantly, and the difference matters because one is a $70 jump start and the other is a repair bill. Here is how to tell them apart before you spend anything.

Signs it is the battery

• The car was fine yesterday and dead this morning
• It clicks rapidly or will not crank at all
• A jump start works and the car runs fine afterward
• You left lights or an interior light on
• The battery is more than three years old
• The car sat unused for a week or more

Signs it is the alternator

• The car died while you were driving it
• Headlights dim or brighten as engine speed changes
• The battery warning light came on before it died
• You get a jump, drive off, and it dies again shortly after
• You smell burning rubber or hear a whining noise
• You already replaced the battery recently and it died again

The single clearest test

If a jump start gets the car running and it keeps running after the cables come off, the alternator is doing its job and the battery was the problem. If it dies again within minutes, the alternator is not charging.

That is exactly what we check on every call. After the jump we measure the voltage with the engine running. A healthy charging system reads roughly 13.5–14.5 volts. If yours reads near 12 or lower with the engine running, the alternator is not keeping up and you need a repair shop rather than another jump.

Why we tell you either way

We only do jump starts. We do not sell alternators or batteries, so we have no reason to steer you toward one answer. If your charging system is bad, we will say so and you can plan for a shop instead of calling us again next week.

What it costs

Flat $70 for cars, SUVs, vans and pickup trucks (gas or diesel) anywhere in our service area, 24hrs, arriving in about 15 minutes on average. We come in a clean sedan rather than a tow truck, and our jump packs are regulated so they are safe for European and luxury vehicles.

Serving: Fort Lauderdale | Hollywood | All of Broward County