How to Charge a Car Battery
Ellie Dyer-Brown, 2 months ago
5 min read
- Battery
- How to
- Car ownership
- Maintenance
WhoCanFixMyCar provides a step-by-step guide to charging your car battery.
Car batteries can go flat for many reasons, not always requiring a replacement. Sometimes, a quick recharge is enough to get you back on the road without visiting a mechanic.
Find out everything you need to know about battery charging in this guide.
Contents
Why do batteries go flat?
Batteries can go flat due to...
Too many short journeys that don’t give them time to fully recharge.
Overuse of devices when the car isn’t running.
Leaving headlights or interior lights on overnight.
Extreme temperatures (both hot and cold).
Read this guide for advice about how to get the most out of your battery.
How to check which type of battery you have
Before rushing to the shops, check what kind of battery you have to ensure you buy a compatible charger. There are two main types of chargers on the market.
Standard chargers: if you’ve got a lead acid battery and are looking for a simple charger to get the job done, then a standard one is ideal. Please note they aren’t suitable for vehicles with stop/start technology.
Smart chargers: Smart chargers are designed for AGM or EFB batteries and tend to be a lot more technologically advanced, enabling them, for instance, to charge in stages for more efficient charging and switch to a trickle charge when your battery is full to avoid over-charging.
How to charge your battery
1. Check the battery terminals
Once you’ve bought the correct charger, inspect the battery terminals and the clamps that connect them. If they look dirty or corroded, clean them before recharging.
2. Disconnect the battery
It’s advisable to disconnect your battery before you begin charging, though you can do the process while it is still connected. Ensure you have your PIN code to hand as you may have to reset things like your car electrics when you reconnect the battery.
Always disconnect the negative (black) lead first and reconnect it last; otherwise, you might get a shock when you touch the negative terminal.
A clamp usually connects the terminals to the battery; it can be loosened using a bolt on the side. Undo the terminals (negative first) and move them out of the way.
3. Connect the battery charger
Once you’ve disconnected the battery it’s time to start charging. Connect the charger clamps to the terminals on your battery, matching positive to positive and negative to negative. While doing this, keep the charger as far away from the battery as possible. Then, plug the charger into the mains.
4. Switch on the charger
The penultimate step is to switch on the charger and give your battery plenty of time to charge.
How long should you charge a battery?
The answer to this question depends on the type of charger you have. If it’s a standard charger, always consult the instruction manual to determine how long it will take.
Smart chargers assess the condition of your battery and automatically switch over to what’s known as a ‘maintenance charge’ to avoid overcharging.
5. Disconnect the charger and reconnect the battery
That’s it. Unplug and disconnect the charger clamps - then, all that’s left to do is reconnect the car battery (positive first, negative last), and you are done.
Still experiencing battery problems? WhoCanFixMyCar can help by connecting you with reliable garages in your local area.
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