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The reason they say to remove the negative first is because it is safer for you. The negative cable in all modern cars is attached to the chassis of the car. SO when you put your wrench on the negative post to loosen it, and the wrench hits the chassis, nothing happens.
Should I disconnect positive or negative when working on car?
When disconnecting the cables from the old battery, disconnect the negative first, then the positive. Connect the new battery in the reverse order, positive then negative.” When you are replacing your car battery, It isn’t always easy to remember the order in which to disconnect and reconnect the terminals.
What does disconnecting the negative battery terminal do?
If you remove the negative clamp and inadvertently complete a circuit to ground, there will be no current flow because the ground clamp is already grounded. Subsequent shorting of the positive terminal to ground will then produce no current flow because the current has no return path to the negative post.
Is it OK to just disconnect the negative terminal?
In order to disconnect the battery, all you have to do is remove the cable from the negative port. If the cables do make contact or even get close, it could do a number of harmful things to your car, including frying your alternator, damage the cables, or worse, cause serious injury to yourself or others.
Do you have to disconnect car battery when working on car?
Disconnect the battery whenever working on anything which is voltage sensitive, such as the Engine Control Unit (ECU – vehicle’s computer). This especially applies when working on the airbag system (SRS), though other precautions need to be taken there as well.
Do you have to disconnect both battery terminals when working on a car?
You don’t need to disconnect both of them, one will suffice. And whenever you’re back, just connect it again. Chances are, your battery might still have some current left to start your vehicle and when your vehicle will run, it’ll recharge again.
Should a battery spark when disconnecting?
Yes, a battery should spark when connecting it. As long as your battery is dead or unconnected, the light won’t get what it’s looking for. The second that your battery is connected, your light can suddenly get the electricity it’s been asking for, so a little spark will occur.
How long will a car battery stay charged if disconnected?
When stored properly out of the car in a secure place, a detached car battery has the chance to last up to six months. Just like any other car battery, it will need charging, but not as often as if it were attached. Giving the battery a charge around every 12 weeks is a good rule of thumb.
When disconnecting the battery the correct tools to use are?
Most but not all battery-cable clamps have 10-millimeter bolts, so you’ll likely need a 10-millimeter open-end wrench to disconnect the cables. A socket-wrench set that includes that same-size socket will be helpful as well. In some cases, you can get by with just an adjustable open-end wrench.
What will happen when you disconnect the wire to the battery?
If you disconnect the wire, the magnetic field disappears and the nail is no longer a magnet. The current flowing through the wire makes the wire hot and drains the battery quickly.
Which battery cable do I disconnect to not drain the battery?
When disconnecting a car battery, always remove the negative connector (negative clamp) from the negative terminal first. This is to avoid electric shocks or sparks.
Should I disconnect car battery before removing fuse?
Before you start working on any automotive project, it’s important that you turn off the engine and disconnect the battery, especially before doing any electrical work. Any misstep with automotive wiring while the battery is hooked up could cause further damage and potentially give you an unpleasant zap.
Why is it necessary to disconnect first the battery before removing the drive belt?
Simple reason. The entire body of the car along with the engine is connected to the negative terminal of the battery. If you’re disconnecting the positive terminal first, and the spanner touches any part of body or engine, you’ll get a massive spark and potentially damage your battery also.
Which battery terminal do you disconnect to check alternator?
Do I disconnect the positive or negative to check the alternator? Disconnect the negative battery cable before testing an alternator. Instead, use a voltmeter to perform a basic and safe test.
What happens if you connect the negative terminal first?
It is only a safety issue. If you first connect the negative cable, then when you connect the positive cable there is a chance the wrench will complete a circuit between the battery and the chassis of the car. This will at a minimum generate a spark, but that spark could eject molten metal toward you causing injury.
How do you not get shocked when changing a car battery?
You may have found that your battery needs replacing after it failed to turn over, so your keys may still be in the ignition. If so, remove them. Without the keys, your car’s electrical system shouldn’t be active, which will reduce the chance of a spark or shock while you’re changing your battery.
Can battery drain when disconnected?
No, it won’t drain overnight if you disconnect the positive lead. However, it’s very bad practice & can be dangerous, assuming the car is negative earth/ground.
How long should I keep my car running to charge the battery?
Be sure to drive your car for about 30 minutes before stopping again so the battery can continue to charge. Otherwise, you might need another jump start.
