can your car battery recharge itself

[DiSimon]

No, a standard car battery cannot recharge itself. It requires an external power source, which in a vehicle with a combustion engine is the alternator. The common belief that a battery "recharges itself" comes from this process: as you drive, the engine turns the alternator, which generates electricity to power the car's systems and replenish the battery's state of charge. However, this is not a self-sustaining cycle. If the battery is deeply discharged (e.g., from leaving lights on), driving may not fully recharge it, and a dedicated battery charger is often needed.

The ability to recharge is also influenced by the battery's health and technology. Traditional lead-acid batteries suffer from sulfation, where sulfate crystals build up on the plates if the battery remains in a low-charge state, permanently reducing its capacity. Modern Absorbent Glass Mat (AGM) batteries, common in vehicles with start-stop systems, are more resilient and can handle frequent charging and discharging cycles better.

Battery Type	Primary Recharge Method	Can it 'Self-Recharge'?	Key Consideration
Standard Lead-Acid	Vehicle's Alternator	No	Requires extended driving; short trips can lead to discharge.
AGM (Absorbent Glass Mat)	Vehicle's Alternator	No	Handles deep cycles better than standard batteries; requires a compatible charger.
Lithium-Ion (In EVs)	External Charging Station / Regenerative Braking	No	Regenerative braking adds range but does not fully "recharge" the main battery.
Dead/Deeply Discharged	External Battery Charger	No	A severely drained battery may not accept a charge from the alternator alone.

For a battery to maintain its charge, the vehicle must be driven regularly and for sufficient distances. Frequent short trips where the starter drain is high and the alternator doesn't have enough time to replenish the energy can lead to a chronically undercharged battery, eventually causing it to fail. The only exception to the "no self-charging" rule is in electric and hybrid vehicles, where regenerative braking captures kinetic energy during deceleration and converts it to electricity, but this is still an active charging process, not a passive self-recovery.

[LaRhett]

Not on its own, no. Think of the battery like a water bottle. Once you drink it, you need to refill it from a tap. In your car, the alternator is that tap. It only refills the battery when the engine is running. If you leave your interior lights on overnight and drain the battery, sitting in the driveway won't help. You need to jump-start the car so the engine can run and the alternator can get to work refilling it.

[StMary]

Absolutely not, and this is a key point of confusion. The battery's only job is to store power. The alternator is the component that generates electricity. When your engine is on, a belt spins the alternator, which produces the power for your spark plugs, lights, and radio, while sending any extra back to the battery. If the alternator fails, a brand-new battery will be drained in a matter of miles because the car is running solely on the battery's stored energy with no way to replenish it.

[Yolanda]

This is a great question because it gets to the heart of how a car's electrical system works. The battery doesn't have a magical way to create energy; that would violate basic physics. It needs a generator, which is the alternator. Even the "self-charging" term some hybrids use is a bit misleading—they still rely on the gasoline engine and regenerative braking to feed energy back to the battery. For a traditional car, the rule is simple: if the engine isn't running, the battery is not charging.

[CeciliaLynn]

No, it can't. Relying on that idea is how you get stranded. A battery slowly loses charge even when the car is off due to parasitic drain from things like the clock and security system. If you only take short trips, you're using more power to start the car than the alternator can put back in those few minutes. Over time, this kills the battery. The best practice is to take a longer drive at least once a week to ensure the battery gets a full, proper charge from the alternator, or use a maintenance charger if the car sits for long periods.