Which Battery Terminal to Disconnect When Working on A Car

For those of us with little to no car knowledge, doing any sort of work under the hood of our car is a pretty terrifying idea. Not because of fear of destroying crucial components of the car, albeit this is a logical fear to have. Many of us are terrified of the prospect of putting our lives in danger when it comes time to disconnect and reconnect our car battery. So many movies show people being cartoonishly electrocuted with a slip of the finger onto the battery. But working around this integral part of your vehicle doesn’t have to be so terrifying.

Which Battery Terminal to Disconnect When Working on A Car

Which Battery Terminal to Disconnect When Working on A Car

Whilst there is no overt danger posed by mistakes when working with a car battery, it’s important to detach the negative terminal first. If you do this in the opposite order there are many problems that can arise from the extreme to the acute. When you disconnect a battery terminal, it is best to label the cable in some way to ensure you are always reconnecting the correct cable to the correct terminal on the battery.

What Happens if You Disconnect The Positive Terminal First

Safety problems

The common perception of disconnecting a battery wrong is that you will either burst into flames or fall to the ground in an electrocuted mush. The fact of the matter is if you disconnect the positive terminal first you don’t need to be too worried about safety. Due to the voltage of a car battery, you can hold onto both of the cables without any major danger of electrocution. But if you happen to touch both negative and positive together in some way you risk sparks shooting off the battery terminals. This can also be a result of touching the positive terminal and another metal/non-insulated part of the car.

Vehicle damage

Not only can sparks potentially flying off your battery pose issues for you but also your car. Fuses can blow and the knock-on effects of unnecessary voltage flowing through your car can disable or completely fry a variety of electronics. The sparks also provide a risk of a fire starting or an explosion which could see you lose your entire car.

How Do You Disconnect a Car Battery

Disconnecting a car battery is thankfully one of the simplest and most straightforward tasks required as part of car maintenance. All you are going to need is a wrench and depending on whether you are cleaning the terminals of the battery or otherwise, you may require additional tools.

Step 1: Unlock all car doors

This may seem like an absurd thing to do in this process, but the fact of the matter is you pose a potential risk of being completely locked out of your car when you disconnect your car battery. If you happen to make a mistake and cause voltages to flow through your car, you could blow the fuse for unlocking your doors and ruin any chance of getting back into your car.

Step 2: Ensure everything is switched off

A crucial step for reducing the chance of sparks is switching all accessories in the car off, including the radio and clock.

Step 3: Unscrew the negative terminal

Using your wrench, start unscrewing the negative terminal on your battery, this is usually indicated by a black cap or black sign of some variety. For recent models of cars, you will be able to determine which one is negative because it will be attached to the car chassis or frame in some way. This may require unscrewing before the terminal can be detached.

Step 4: Stow negative cable

To minimise any chance of misplacing your cable or having an incident of sparking, it’s a good idea to keep your cables in plain sight. You could use a rag to tie the cable, not the connector, to the car. Otherwise, hanging cables over the sides of the car with the connector away from any metal.

Step 5: Unscrew the positive terminal

Taking care not to touch the other terminal whilst detaching, take off the positive terminal and stow similarly to the negative cable in a different place.

Once you connect a new battery, be prepared for about 10 bad ignitions when you start your car. You will also need to inspect any electronics to ensure they are up to date. For instance, you will need to recalibrate your clock.

How Long Does A Car Battery Usually Last?

Some people will tell you their car battery has been running smoothly for 15 years, but this is an absolute fluke. Most of us using our car for more than 4 trips a week will get a 3-year lifespan out of our car batteries. If we are conscious of how we can maximise the lifespan of our battery,  5 years is a healthy target to have.

What Affects Battery Life?

There are a lot of different variables that determine the life of your battery. Your climate will change how long your battery survives. If you live in a hotter, humid climate this will be a surprising blessing for your battery. The battery is mostly giving its power to the ignition of a car but still plays a small part during the operation of a vehicle. When a car operates it gets hot, this is good for keeping an operational battery, but driving your car too much will have a negative effect. If you live in a cold climate, try to do a short trip every day or use a battery maintainer.

Do I Need to Recharge My Car Battery?

At the very least you should be recharging your battery every 6 months, even if you don’t use your car every day. However, you can purchase a battery maintainer to plug in while you are not running your car, this will ensure the battery deteriorates at a healthy rate. Many people going overseas for a trip choose to enlist help from a friend to turn over the engine of their car and keep their battery healthy.

Can You Bring a Dead Battery Back to Life?

Sometimes you won’t realise how long you’ve been driving without inspecting your battery and will be seemingly stranded. It’s important to prioritise installing a new battery as soon as possible if you have a dead battery, but you can get back on the road in the meantime. If you have invested in a battery maintainer, you can use this to not only prolong your battery but also to revive a dead battery. Batteries that have been recharged from the dead will not work at full operation again and will only give you a maximum of 10 trips before issues will present themselves. You can also use jumper cables with another car to restart your car’s battery for a limited time to get back to safety.

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