Step By Step Guide on Charging a Car Battery

    Charging a Car Battery

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    A car battery is very important to have a smooth and safe driving experience. Once the battery weakens, you will notice that your car becomes sluggish and slower. There are instances that you need to jumpstart your vehicle because your battery just can’t start right away. Follow this simple but useful guide on how to charge a car battery using your car battery charger.

    Why Car Batteries Do Go Flat?

    There are many reasons for batteries to go flat or lose charge. Basically, a car battery is only used to crank the engine. But like most batteries, once it reaches the end of its lifespan, it loses its capability to hold its charge and will often go dead. Other factors can also shorten the life batteries:

  • Faulty alternator (how to test it?)
  • The use of onboard electronic devices when the car isn’t running
  • Frequent short trips doesn’t allow the battery to completely recharge.
  • Leaving interior light on overnight when the car isn’t in use can drain the battery.
  • Overcharging a battery.
  • Extreme hot and cold weather.
  • Two things are required to charge a car battery; a voltage source powerful enough to move current through battery, and time. The more current you push into a car battery, the faster you can charge it. However, charging a battery at too high a rate can lead to overheating.

    The time/rate a car battery recharges depends on many factors, like if the battery is cold. Check the temperature of the battery during charging. Once gets too hot, stop charging and continue when it cools down.

    Preparing to Charge 

  • If it is needed to take the battery away from the car to recharge it, make sure to remove the grounded terminal first. You also need to ensure all car accessories like radio and lights are off to avoid arcing.
  • Make certain the area surrounding the battery is well-ventilated while it is being charged.
  • Clean the terminals of the battery before charging. During cleaning, use a mask to avoid inhaling airborne rust. Use water and baking soda to defuse battery acid. It also helps get rid of airborne corrosion. Avoid touching your nose, mouth and eyes to prevent irritation.
  • Pour water into every cell until the acid of the battery reaches the specified level by the manufacturer. Don’t overfill. If your battery doesn’t have cell caps, follow carefully the recharging instructions provided by the battery manufacturer.
  • Read carefully and follow the guides for the battery, charger car and any tools utilized near the battery and charger. Understand the manufacturer’s specific safety measures while charging and follow the suggested charge rates.
  • Know the voltage of the car battery through referring to the vehicle manual and make certain that the switch of the output voltage selector is in the right voltage. In case your charger is equipped with an adjustable charge rate, charge first the battery starting with the lowest rate.
  • Make sure the charge cable clips make light connection.
  • Car Battery Charger location

    Put the charger as far away from the car battery as the DC wires permit. Avoid placing the charger above the battery being charged; gas from the car battery will damage and corrode the charger. Avoid putting the car battery on top of the charger. Don’t let the acid of the battery to drip onto the car battery charger when filling the batter. Don’t operate your car battery charger in a confined space.

    new car battery

    DC Cables Safety Measures

    Connect and detach the DC output clips after the charger turns off and remove AC plug from the outlet. Make sure the clips don’t touch each other. Connect the clips to the chassis and battery. click here to read the full review of Jumper cables.

    How to Charge a Battery When It is installed in the Car?

    A spark near your car battery may lead to the explosion of the battery. To avoid this from happening:

  • Steer clear of belts, fan blades, pulleys as well as other components that can cause damage.

  • Check the polarity of the car battery posts. These will likely have a mark and are usually color-coded. In some applications, the positive post is bigger than the negative post.

  • For a NEG-grounded car, connect the RED or POS clip from the charger to the POS underground post of your battery. Connect the black clip to the car chassis, make sure it is away from the battery. Avoid connecting the clip to the fuel line, carburetor and sheet metal parts. Connect to heavy gauge metal portion of the engine block.

  • When detaching the car battery charger, make sure all the switches are turned off, disconnect the AC wires, get rid of the clip from the chassis of your car and then take away the clip from the terminal of the battery.
  • If you have an older (vintage by today’s standards) car, you may need to verify if your vehicle is running a Positive-ground or Negative-ground electrical system. The easiest way to check is to follow the leads from the battery and determine which one is directly connected to the chassis.

  • For a POS-grounded car, connect the black clip from your charger to the NEG underground post of your battery. Connect the red clip to the chassis, away from the battery. You also need to avoid connecting the clip to sheet metal body parts, fuel lines or carburetor.
  • How Long You Should Charge Your Car Battery

    If the voltage of your battery is below 11.85 and the charge is putting out a 5-amp charge rate, then it will take about 12 hours to fully charge your battery with 400 to 500 cold cranking amps. If the battery has ten amps charge rate, it will take six hours to fully charge. When the battery has low open-circuit voltage, it will take 12 hours or more to fully charge.

    Where to Buy the Car Battery Chargers

    Now, you are considering buying the car battery chargers. Please check out the car battery charger reviews. We put down a list just for you so that you don’t have to spend countless hours searching for the right car battery charger that suits your needs.


    With the use of car battery charger, it is easy for you to jumpstart your battery. But make sure to buy high quality car battery charger. You can contact professional mechanics for some tips on choosing the best car battery charger.

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