How to Charge a Car Battery

Not sure how to charge a car battery? Wondering how long it takes to charge a car battery? Not sure if you need to disconnect a car battery to charge it?

You're in the right place, as our guide to car battery charging has the answers you need to help you get powered up and back on the road.

Car batteries can go flat for a number of reasons. If you forget to turn your lights off when you park your car, or you leave your car parked for a long period of time, you might come back to find that the battery doesn't have enough charge left to start the car.

Even if you jump start as a quick fix, it's a good idea to look into charging a car battery properly to keep it in good condition.

How to recharge a car battery

  • Check what kind of battery your vehicle has:If your car has start/stop technology, you'll have an AGM or EFB battery. A conventional charger isn’t suitable for these types of batteries, and you’ll need a 'smart' charger instead. If you're not sure what kind of charger your battery might need, pop into one of our stores and we can help you out.
  • Check the contacts: Before you connect anything, take a look at the lead terminals coming out of the top of your battery, and the clamps that connect them. If they look dirty or corroded, you'll need to clean them before charging your battery.
  • Disconnect your car battery: Although charging a car battery while still connected or in situ is possible, it's always a good idea to disconnect the battery before charging after a quick clean. Always disconnect the negative (usually black) lead first and reconnect it last, otherwise you could end up getting a nasty shock when you touch the positive terminal. The terminals are usually connected to the battery by a clamp, which is loosened or tightened by a bolt on the side. Undo the terminals (negative first, remember!) and move them to one side. Plus, remember that if you disconnect your car battery, you might need to reset your radio, seat positions and dashboard settings, so make sure you've got the security codes if you need them!
  • Connect the charger: Keep the charger as far from the battery as the cables will allow, and never leave the charger on top of the battery while it's charging! Connect the clamps of the charger to the terminals on the battery, matching positive to positive and negative to negative. Then, plug the charger in.
  • Turn on the charger: Some chargers will turn off automatically when the battery is charged, but others will need to be disconnected. Check the manual for your individual charger to find out how long it will take and what you need to do. The other option is to invest in a smart battery charger, which will assess the condition of the battery and tailor the charge cycle to fit, automatically switching to a maintenance charge rather than over-charging the battery.
  • You're done! Once the battery is charged, unplug the charger and disconnect the clamps. Then, reconnect the car battery (positive first and negative last, remember!) and away you go! If you're using a smart charger, there will be an indicator to show you when the battery is charged.

Things to remember

Charging your battery is simple, but batteries can give off hydrogen gas while they're being charged - especially if they're being charged at a higher voltage by a fast charger. Keep the charger away from the battery, and make sure you don't leave anything on top of the battery.

Regular care and maintenance can extend the life of your battery, saving you money long-term. A smart charger can repair pre-existing issues as it charges, and help to prevent any further damage, so regularly charging with one can save you having to purchase a new battery sooner.

Also remember that batteries don't last forever and if your battery is losing charge, it may have reached the end of its life. Halfords can check your battery for free and advise if a replacement is required, so book a Free Battery Health Check to be sure.

You should now be a car battery charging expert and ready to get back on the road again. You can take a look at our range of car battery chargers and new car batteries. For a free battery check, you can book here or head to your local store or autocentre.

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