What happens when you disconnect the negative battery cable?

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.

Can a car battery drain with the negative cable disconnected?

Be safe: always disconnect negative first. Disconnected either terminal will prevent drain, as stated already. A battery tender is another safe way to maintain the battery.

What battery cable do you take off to check alternator?

If you’re tempted to test an alternator by disconnecting the negative battery cable, don’t do it. A good alternator may indeed keep the engine running without the negative cable, but this was never a good test. In the pre-computer days, you could pull it off without damaging anything.

Should I remove positive or negative first?

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.

Will disconnecting battery keep it from draining?

“If someone is going away for a few months over the winter, they should definitely disconnect the battery. It’s the only way to prevent battery drain,” Rashidi said. In some instances, more serious issues can arise when disconnecting or reconnecting the battery.

What causes battery drain in a car?

“Electrical devices or lights left running, a defective charging system or alternator, and extreme weather are some common reasons but maybe it’s just time to get a new battery.”

When removing a car battery which terminal is disconnected first?

How can I tell if my alternator is bad?

7 Signs of a Failing Alternator

1. Dim or Overly Bright Lights.
2. Dead Battery.
3. Slow or Malfunctioning Accessories.
4. Trouble Starting or Frequent Stalling.
5. Growling or Whining Noises.
6. Smell of Burning Rubber or Wires.
7. Battery Warning Light on Dash.

How long will a car battery stay charged when disconnected?

A brand new, fully charged battery will last two months or more. That said, it’s not a good idea to leave them this long. An older, weak condition battery will lose its charge much more quickly. If your car has an alarm system, the battery will go flat more quickly.