To charge a battery, it is recommended that you run your car for 20 minutes and then let it cool down.
running the motor acts as a giant alternator, producing current to replenish the energy used during start-up. the alternator has an internal regulator system which will produce just enough power to replace what was used up–normally around 13.5 volts with no accessory load on the engine. running your car at idle may damage its catalytic converter because of incomplete combustion at low rpm's where the engine does not produce enough oxygen for complete burning of fuel. you should never leave your car running unattended so use caution!
Do car batteries charge while idling?
It depends on the temperature of the engine.
the sensor that detects whether or not a car battery is fully charged is also sensitive to temperature. if your battery voltage doesn't appear to be charging while the engine's running, it could be that this sensor may need thermal recalibration as a result of either overheating during prolonged idling or extended periods void of use.
How long does it take to fully charge a car battery while idling?
If you're using a decent battery charger like the one pictured below, it takes about 15 minutes to charge up your car's 12-volt lead-acid battery (which is what most cars use).
The overnight trick that some people recommend isn't really necessary; it doesn't take much power for you to keep an alternator ticking on. what is important, though, if you want your car battery barely detectable on the next morning, is not kicking on the headlights and leaving them on all night. that can drain a batteries even while idle. a sleep mode with the dome light or limiting how many times you start and stop your engine will help preserve your battery life too.
How long do I need to run my car to charge the battery?
The battery will be charged after a certain amount of time has elapsed.
it takes about 3 hours if the ignition is on, or up to 18 hours if the engine was turned off.
charging can also take longer in cold weather because batteries work less efficiently in low temperatures. so an average person would need to run their car for about 18 hours before their battery is fully charged. charging a 12 volt 10 amp-hour battery from standby should take up an hour and a half worth of driving distance at highway speeds, 30% – 50% charge per hour for 12 volts between 10 and 100 amp-seconds capacity with constant charging, two full charge/discharge cycles per day (12 hrs.) or one cycle per day.
Does revving the engine charge the battery?
The energy in a car battery is not stored in the electrical cables that link the battery to the starter. the starting memory in cars today prevents early transmission of starter current, which would damage sensitive computerized components. charging an automobile battery initiates when an alternator charges it.
Starters are mainly resistors which consume electric power without generating any voltage themselves. you have to have at least 12v or so before you can get 1000 amps from your engine crank-spark for example, so 12v left over doesn't go into charging your car's battery no matter how much torque is applied against the starter clutch plate by rotating crankshaft and flywheel assembly – unless you have a really powerful charging system that might provide some amps. even if starter is disabled, you still need at least 12v to engage the solenoid that releases the starter-clutch. To answer this question, it's necessary to know how the starter works. It is usually attached on the outside of the flywheel using 3 or 4 bolts. The starter motor is connected to the crankshaft by a long steel bar (called torque rod) and when you press the pedal to start the engine, you engage a gear shift and push the rod to rotate the crank and flywheel. When your engine starts (and there is spark to ignite the fuel) then the crankshaft rotates and engages a small gear that's attached on the starter-clutch plate. This frees the starter to spin and turn the flywheel and crankshaft and by this means gets your car started. Now, if you rev the starter-motor, by turning the flywheel or crankshaft fast enough (with no load) then you can create an electric spark inside the starter motor itself, which might start it.
