You’re about to start your car when you notice the battery warning light indicating the alternator has failed. Now you’re worried the engine won’t start without the alternator charging the battery. Thankfully, most vehicles can be started normally even with a dead alternator in place.
This article explains why a car can be started without an alternator, for how long, precautions to take, and steps to get your charging system functional again. Read on to learn why all hope is not lost when your alternator dies on the go.
Table of Contents
Why an Alternator is Not Needed for Engine Starting
The alternator’s job is to generate power when the engine is running, not during starting. This allows:
- The battery alone provides the initial jolt of power needed for ignition and the starter motor to crank the engine.
- Once started, the alternator takes over recharging the battery and powering systems while the engine runs.
- With a dead alternator, the battery sustains this process until it eventually drains.
So at the moment of ignition, the alternator plays no role. The starter only needs battery voltage to function. Think of the battery as the match lighting the engine.
How Long You Can Keep Starting Without an Alternator?
While starting is still possible right away, a dead alternator means available starts are now limited:
- Most vehicles allow at least several days of occasional starts with no recharging before the battery is dead.
- More frequent starting drains the battery faster. Extended cranking also drains battery.
- High temperatures in the engine compartment accelerate discharge compared to cool weather.
Monitoring voltage level prevents getting stranded when the battery reaches empty:
- 12.6V or above – Good starting voltage.
- 12.0V – Starting voltage decreasing but still enough for starts. Charge soon.
- 11.8V – Very low charge left. Few possible starts remain.
- 11.0V or less – Almost fully discharged. Engine may not turn over. Needs immediate charge.
So while starting remains possible for awhile, continual driving with a dead alternator will soon leave insufficient voltage to crank the starter.
Steps to Take if Your Alternator Fails
Follow this game plan after diagnosing a bad alternator to avoid getting stranded:
- Turn off all unnecessary electrical accessories to conserve battery charge for starting.
- Drive directly to your repair shop or home using minimal stopping and idling. The running engine helps partially recharge the battery through its own residual voltage.
- Once home, avoid starting again until the alternator is fixed or the battery is recharged. Jump starting can also provide temporary starting capabilities.
- Replace or repair the bad alternator and have the charging system inspected by a professional to prevent more issues down the road.
With some smart precautions, you can still get around temporarily before the dead alternator causes a no-start condition. But seek repairs quickly.
Other Charging System Tests Once Alternator Fails
Once the alternator goes out, also check:
- The battery age and state of charge. Old weak batteries may need replacement along with the alternator.
- The drive belt condition. Glazing, cracking and fraying will lead to premature belt and alternator failure.
- Connections at the battery terminals are tight and free of corrosion. Clean if needed.
- No loose accessory pulleys are present. Spin each one by hand checking for play.
Thorough inspections help reveal underlying issues that shorten alternator lifespan when fixed.
Signs of Impending Alternator Failure
Watch for initial clues of alternator demise before it leaves you stranded:
- Dimming or flickering headlights when accelerating. Especially at night.
- Battery unable to hold a charge between drives. Needing jump starts.
- Whining or squealing noise from a failing alternator bearing.
- Burning rubber smell as belt slips from lack of charge.
- Voltage gauge dropping far below 14 volts when engine revs high.
Catching problems early allows replacing the alternator before getting caught off guard with a dead battery on the road.
While inconvenient, a failed alternator does not inhibit immediately starting your car due to battery power still present. But seek prompt repairs to avoid getting stranded as continual driving eventually drains the battery completely. With quick action, you can still drive as normal for awhile before loss of charging takes its toll. But monitor voltage level closely once the alternator fails as available starts are now on borrowed time.