Does A Car Battery Charge At Idle, Or Does The Engine Need To Be At Higher RPMs

Posted in Car Batteries

Finally got my range rover started, left it idling for about 40 minutes, drove it around for about 15, and tried to start it — barely started. Battery was completely dead before the jump. Now I’m going to leave it idling for a few hours, will that effectively charge the battery, or should I just head to kragen for a battery charger?

Battery was replaced about a year ago, so I don’t think I need another one.

There are 10 Answers for "Does A Car Battery Charge At Idle, Or Does The Engine Need To Be At Higher RPMs"

    1. mr5oh says:

      Depends on the alternator, most will charge at idle, a very worn alternator may not charge much at idle though. Are you sure your battery is good?

      If you battery was that dead, it may have killed the battery.

      The other option is your starter could be bad. An old starter will require more amperage to turn over, eventually it gets to where your starter requires to much power to turn over, making it seem like you have a dead battery as it won’t have enough power to turn over a worn out starter.

      I’d charge and check your battery. Assuming your starter is good, on a full charge a battery should never drop below 10.5 volts while cranking over the motor.

    2. lees68tbird says:

      The alternator should be able to charge a battery at an idle. If it cannot then it is not working right, but it could also be a regulator problem or something of the like.
      You can test the alternator by starting the car and disconnecting the batery. Turning on the headlights to create a load on the electrical system. The alaternator should be able to support a load without the car battery.

    3. J.R. says:

      You may still need a new battery, especially if yours was completely drained. An alternator will charge at idle, but not quite as well as it would at driving speeds. Take it by Kragen and see if they will test the battery for you. 55 minutes should have charged it enough to start properly, but would not be enough to fully charge it.

    4. millionsofsubys says:

      Even at idle the battery should charge. If your battery is only a year old, it may be another problem.

    5. Big C says:

      IF everything is working properly, you battery will be charged ever so slightly.

      What you need to do is take it to AUTO ZONE or another parts store that will do a FREE battery and alternator check. I got a battery, supposedly brand new, from Auto Zone, and it lasted for 3 months, cuz one of the cells died. Also, your altenator might be going bad. If you have a loose belt this will effect charging. The belt has to have a certain tension on it for the battery to be charged.

      If the battery had a weak cell, it will take a charge and start up right away, but then when you start using the juice, the weak cell prevents the battery from being properly charged by the altenator, so then you have a bad battery. Anyway, get it check first before you buy the charger. Just because you buy something new, never rule the part out.

      Haynes Manual
      What you do is get the Haynes Repair Manual for your Year and model of vehicle at Auto Zone, or another automotive repair shop. The manual will show you what and how to do the repairs.

      Bookmark this. ^(

    6. jbradc69 says:

      Some alternators will charge at idle but most companies recommend the car be at higher rpms for good charging, try driving the vehicle for 20 – 30 minutes and see what that does. If that does not work you either have a bad alternator or a dead cell in your battery…good luck

    7. south418 says:

      it depends on the year of it older cars the more rpm the higher the alternator juice is and the newer models charge the same at idle as they do at higher rpms hope this helps ya . ps you can get a volt meter and touch the battry post while the engine is running to see if it puts out any juice and give it a lil gas to see if it gets higher . one sure way in knowing

    8. cy says:

      Sounds like the battery is DEAD. Replace the the battery with new.