Stopped car: can you disconnect the battery?
One of the most common habits adopted by those who intend to leave the car idle for more than fifteen days is to disconnect the battery in order to prolong its useful life.After all, the car battery - even when new - is the first component to suffer from disuse. Take this post for more insights: how long can i leave my car running while parked
Electronic accessories, such as an alarm and even the radio in standby, in addition to the memories of on-board electronic units (such as the engine control, Airbag, ABS brake, etc.), consume between 20 to 30 milliamps of the battery even with the car turned off.
Therefore, many owner's manuals already indicate disconnecting the claw from the battery negative post to leave the car stopped for more than fifteen days, precisely to avoid cases of dead battery.
It is important to point out that disconnecting the battery without the assistance of a specialist or without following the indicated safety procedures can deconfigurate the electronic injection modules, generate an electrical failure, a short circuit or even cause fires.
Although it is not recommended, it is possible to disconnect the cables from the car battery without taking such risks, as long as the process is carried out correctly, with full attention and respecting a series of basic precautions, as listed below.
Turn everything off and wait at least ten minutes
First of all, you should turn off all electronic equipment in the car and keep the vehicle turned off for at least ten minutes (preferably with the engine cold).
This is because “the car modules remain on stand by for a few minutes, even after the engine is turned off”, as explained by the Automotive Maintenance Technician, Caíque Ribeiro, from Mix Auto Center.
By removing the battery without waiting for this time interval, you can corrupt the data stored by the modules still in operation, unconfiguring the “adaptive car memory”.
Disconnect the negative terminal first
The big secret to changing the battery or even turning it off lies in the polarity of the positive (+) and negative (-) terminals.
The terminals are nothing more than the two cables connected between the engine and the car battery. There is usually an indication of the positive (+) and negative (-) pole on the battery itself.
Furthermore, the negative cable can be universally identified by the color black (or dark grey), while the positive cable is colored red.
Attention:
never hold or touch both poles at the same time or you will get a very dangerous shock!
After ten minutes of turning off the vehicle, you can remove the negative battery pole to ensure that, when restarting the car after a long period (more than fifteen days), there is still enough charge to start the car.
Remember: With the battery disconnected, electrical systems stop working. So, don't forget to lock all car doors manually with the key.
Which wire to connect first: positive or negative?
When disconnecting the negative terminal, there is no need to disconnect the positive cable, although you can do this even to change the battery, for example.
What should never be done is to connect only the negative cable, which can result in a short circuit and even melting of the negative pole if the cable comes in contact with the car frame.
Therefore, when deciding to reconnect the car battery or in cases of replacement, it is also essential to follow the correct order to reconnect the cables.
The positive cable must always be connected before reconnecting the negative cable.
It is also essential to securely tighten the cable clips with the wrench in such a way that the cables do not come loose with the vibration of the car.