Changing Your Car Battery

How To Replace Your Car Battery

Don’t Get Caught Out With a Faulty Car Battery


battery warning light


It happens to all of us at some point in our life, if not now, then later on. I’m not talking about old age, I’m talking about your car battery going dead. Most car battery’s last for around 5 years even if you change your car every 3 years there is still a chance you may have a bad battery and it’s just a matter of time before it loses it’s charging abilities.

There are plenty of signs that will tell you that your battery is going to that big scrap yard in the sky. So make sure you look out for these signs: Lights flicking, strange power fluctuation, struggling to start (Especially in the morning) and of course your battery warning light has popped up.

Car Battery Checks

Checking The Car Battery Tray


car battery housing unit


On most vehicles your car battery will be housed in a plastic box which is called a tray. This “Tray” holds the Car battery in place. The last thing we want is a battery flying around in the engine bay when we turn a corner. Look at the tray from all angles that are visible and make sure its in good condition.

Look out for any cracks or damage even corrosion to the tray. If you find visible damage then check to make sure it’s not going to cause any problems later on. Its best to keep your battery housed if your housing is missing then pop off to a scrap yard, they may have one sitting in an old car suitable for your needs.

Check the Car Battery Terminals and Leads


car battery removal

A Bad Car Battery, Replace leads and Battery

Read our guide on safety checks before attempting this.

Remove the top compartment of your battery housing (if there is one). This will allow you to see the cables connected to your battery. One side is negative and one side is positive. Your wanting to check that the clamps are connected firmly (not loose, slipping up and down the terminal), there are no tears or rips in the cables. Also make sure that the terminals look clean with no corrosion.

I can’t say I have ever needed to clean a battery terminal before but if this is something your wanting to do check out this guide: how-to-clean I normally just replace bad batteries there relatively cheap.

Does Your Car Battery Hold a Charge


If you suspect your battery is having problems holding a charge there is a simple way to test it. The good thing about this is it’s a simple to test and only requires the use of a multimeter.

Get hold of a Multimeter if you don’t have one, well now is the perfect time to get hold of one. Set your Multimeter to 20 volts. Make sure your car engine is switched off for this test. Connect your negative probe to the negative terminal on your car battery, then the positive probe to the positive terminal. Switch your multimeter on. It should read at 12 to 13 volts.

Now turn on your car engine (make sure it’s in neutral first though). Wait a minute or so and test the voltage again. If your voltage reading is below 9 volts then your battery will need charging. Once you have charged it up re test the battery to see if the reading is higher. If not chances are it’s not holding a charge.


Are You Sure Its The Car Battery?


In some cases it may not be the car battery to blame but the car Alternator. You can check our guide on alternators and make sure that it’s the battery to blame and not something else. I had a few problems with an alternator a few years back turns out the bolt that was holding the positive cable down was loose and was causing the alternator to fail. It’s always best to double check things before investing in new parts.

Replacing Your Car Battery


If your positive your car battery is to blame then it’s time you learnt how to replace it yourself. Sure you could pay someone to do it for you, but really where is the fun in that? Not to mention your looking at £20 to fit a battery plus whatever ridiculous price the mechanic is charging you for the car battery in the first place. So don’t think about dropping it off at the garage and waiting all day to get your car back, do it yourself in under an hour and put your feet up knowing you have done the job yourself.

Tools You Will Need To Replace Your Car Battery


car battery extension socket bar

A Selection of Extension Bars


Socket set with an extension bar set

You will need a socket set to remove the bolts attached to the battery terminals an adjustable wrench also works but it’s far quicker to use a socket set. Also an extension bar may be needed to reach the deep seated bolt on the battery tray. This may be visible to the naked eye or may require you to remove parts of the engine housing to gain access. Its best to have hold of an extension bar set as they come in quite handy, so purchase some now they will set you back around £5-£10.

The replacement Battery

There are plenty of batteries available on the market. Your wanting to pick a good brand don’t go for the value ones as you want to get the most out of your battery. I picked up a nice battery for just £30 so even for a good battery there is really no need to break the bank. A good rule of thumb is to go with the same make as your old battery (if it was a reliable car battery that is). Just make sure it’s the correct size for your car for a more in depth guide visit: Consumer Reports

Replacement cables – If required

If you noticed any tears, cracks, rips or the terminal ends were corroded. It would be in your best interest and your new Car battery’s interest for you to change these cables.


Disconnecting your car battery


how to disconnect your car battery leads

disconnecting battery cables terminals – wiki how

If you have not already done so remove your battery housing cover. Normally the top half will come off so you can gain access to the battery. There is no need to completely remove the whole tray.

Firstly disconnect the negative connector once you have loosened nut. It should just pull off. Make sure you set it aside, away from the battery. Now loosen the nut on the positive terminal and disconnect it from the battery.

Removing your car battery


Now that your leads are disconnected your wanting to locate the bolt holding your battery down to the tray. There may be one, two or maybe three. There easy to locate and there is normally just the one holding them down. Just look inside your housing and look along the bottom rim of the battery. You should see a piece of metal with a bolt in it attached to the battery. This small bit of metal acts as a grip to the tray “pinning” the car battery down. Stopping it from moving around during transit. In most cases you will need your socket extension bit to reach this bolt it can be quite fiddly to put back on too. But once it’s off you should be able to remove your car battery now.

Please bare in mind car battery’s have a bit of weight so be careful with them and make sure you can lift them without causing injury to yourself.

Installing The New Car Battery


Get hold of your new car battery and slowly place it inside the battery housing tray. Get your retaining metal clip and place it on the bolt hole. Now comes the tricky bit, try to screw the bolt in place. This is much easier with a magnetic socket set. Just requires time and patience to screw it back in.

Once your battery is in reconnect the wires in opposite order to removal. Connect the positive terminal first and tighten the bolts up. Not too tight though just enough to stop play in the cables. Then attach the negative terminal. Do not cross the wires. Then re-assemble your battery housing back together.

Now fingers crossed, start the car. If any problems arise test your new battery with a volt meter to see if it’s holding a charge. If it isn’t it’s most likely to be the alternator that’s at fault.

Now you know how to replace your battery. I recommend checking your battery 4 times per year (1 for every season) and you’ll be able to sort out any problems before they get serious. Now grab a cold one you deserved it!

Be aware that you must dispose of your old battery in the correct way. Most recycling plants (tips) will take them off of you free of charge so just pop it down to them.

Any problems comment below, regards

The Beat The Mechanic Team

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