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Alternator Replacement

The alternator charges your battery and powers everything electrical while the engine runs. When it fails, the car runs on battery alone — and it will not run for long. Auto Care Plus tests the entire charging system, so you replace the alternator only if the alternator is genuinely the problem. Expert diagnosis and quality parts across our New England locations.

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Alternator Importance

You’ve probably noticed a bunch of warning lights on your dash when you start your engine. They flash on to test the circuits and then go off if everything’s OK. One of the warning lights looks like a car battery. Its job is to tell you if your battery’s not charging properly.

You know that your battery stores electricity – enough to start your engine and get you moving. But that’s about it – you can only get a few miles on battery power alone with today’s creature comfort hungry vehicles. You need an alternator to generate enough electricity to run your engine and power your electrical accessories like the stereo, power seats, heater fan, on-board computers, and so on. On top of that, the alternator needs to recharge your battery. So when your alternator isn’t working properly, there isn’t enough electricity for all of those things. When your alternator fails, you aren’t going very far.

Alternator Not Working?

So why would your alternator not work? Usually they’ve simply worn out. Alternators are driven by your serpentine belt and spin 2 to 3 times faster than the engine – that’s a lot of work. The bearings wear out, as do the copper wire coils and magnets that generate the electricity.

There’s no sense in hobbling along with an alternator that’s not working properly. It will fail at some point and leave you stranded. A failing alternator usually will damage a good battery as well. Get a bad alternator replaced as soon as you can. Alternator replacement is a standard service that you can get done at any of our 8 New Hampshire and Maine locations by one of our master technicians. You will also get the peace of mind of a Nationwide 5 Year/50,000 mile warranty covering parts and labor!

And don’t forget if you use a lot of additional electrical gizmos in the vehicle, like computers, DVD players, power inverters and such or may regularly tow a camper trailer, boat or RV that puts and even higher load on your charging system. If that sounds like you, talk with one of our service advisors at Auto Care Plus about upgrading to a more heavy duty alternator to meet your high load needs.

DID YOU KNOW?

When you replace your alternator, it’s a good idea to replace your serpentine belt at the same time. Our technicians will have to remove the old belt anyway so he might as well put on a new one when he’s done. And the number-1 alternator killer is a battery that’s on its last legs; the alternator has to overwork to keep it charged. If your battery is 3-5 years old; you should have us replace the battery at the same time.

Alternator Replacement Video

Frequently Asked Questions

What are the signs of a failing alternator?

The classic signs are a battery warning light, headlights that dim and brighten with engine speed, electronics that flicker or reset, a battery that will not stay charged, and whining from the front of the engine. Ultimately, testing charging output is what confirms it.

Can a bad alternator ruin a new battery?

Yes, in both directions. An alternator that undercharges leaves the battery chronically depleted, which sulfates the plates and kills it. One that overcharges cooks the battery and can boil off the electrolyte. That is why we test the whole system rather than just swapping a battery.

How long does an alternator last?

Most alternators last somewhere between 80,000 and 150,000 miles. Heat, vibration, and heavy electrical loads shorten that. A failing battery that forces the alternator to work constantly at maximum output is a common cause of early failure.

Can I drive with the battery light on?

Not for long. When the battery light comes on, the alternator has stopped charging and the car is running purely on stored battery power. Depending on the load, you may have 20 to 45 minutes before the engine dies — often less at night with the headlights on. Head straight to a shop or call for a tow.

Why did my alternator fail so early?

The most common cause of premature alternator failure is a weak or failing battery. A bad battery forces the alternator to run at maximum output constantly, which overheats the internal diodes and windings. This is exactly why we always test the battery and the alternator together.

Do you test before replacing?

Always. We never replace a charging component without testing it. Battery and charging system testing is free, and it is the only way to be sure you are buying the part you actually need.

Signs you need this service:

  • Battery or charging system warning light on the dash
  • Headlights dim or brighten with engine RPM
  • Electronics behave erratically or reset while driving
  • Battery keeps dying even after replacement
  • Whining or grinding noise from the front of the engine
  • Burning rubber or hot electrical smell
  • Vehicle stalls while driving
  • Vehicle starts with a jump but dies shortly after

Our process:

  • Test battery condition first to rule it out as the cause
  • Measure charging voltage and current output at idle and under load
  • Perform a voltage drop test on the charging circuit and ground connections
  • Inspect the serpentine belt, tensioner, and alternator pulley
  • Scan for charging system codes on vehicles with computer-controlled charging
  • Review results and provide a written estimate
  • Replace the alternator with a quality unit and, where needed, the decoupler pulley
  • Inspect and replace the serpentine belt if worn
  • Verify charging voltage across the full RPM range and under electrical load
  • Confirm the warning light is out and the battery is properly recharging

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