Moderate⏱ 45 min - 1 h12 steps·Original on iFixit ↗

How to Replace a Corroded Car Battery Terminal

Is your car having trouble starting? Is there corrosion build-up on your terminals, preventing a proper connection? This handy guide will help you remove the troublesome terminal and replace it with a brand new one.

Warning: It is dangerous to work on a vehicle battery. Exercise extreme caution when following this guide.

Tools (2)

Shop Towels or Rags buy ↗
Adjustable Wrench buy ↗

Parts (1)

Car Battery Terminal buy ↗

Step-by-step instructions

'''Remember to remove your car key from the ignition and shut off the car before performing this guide.'''
Locate the terminals on the top of the car battery. Next to each terminal is a positive(+) or negative(-) sign, indicating the charge.
The positive terminal looks to be in working order, but the negative end has a lot of corrosion buildup. This terminal needs to be replaced.

Find the nut located on the side of the terminal.
Using an adjustable wrench, rotate the nut counterclockwise to loosen it.
Use an appropriately-sized wrench or socket, not channel locks as shown in the photo.
You do not need to loosen the nut all the way off the bolt, but just enough to loosen the terminal's grip on the node.

'''Always remember to remove the negative terminal first before the positive terminal.''' This will prevent shorting to the ground and possibly causing shock or a fire.
Carefully use a rag to lift up the terminal off of the battery node.
Be cautious when handling battery corrosion, as it can irritate the skin and is harmful if it comes in contact with your eyes.
Place the terminal on a rag or towel and '''make sure it doesn't come in contact with the battery node.'''

On the positive terminal, locate the nut along the side.
Using the wrench, rotate the nut counterclockwise.
You do not need to fully loosen the nut off the bolt, but just enough for the terminal to be easily removed from the node.

Using a rag, carefully remove the positive terminal from the battery node.
Place the terminal on a rag or towel, and make sure it does not come into contact with the battery node.

On the negative terminal, locate the nut on the side facing upwards.
Using the wrench, rotate the nut counterclockwise and remove it from the bolt.

Take the wire plate on top and remove it carefully from the bolt.
At this point, it is fine to handle the metal plate with your hands since the terminals are disconnected from the battery and there is nothing completing the circuit.
Remove the bottom wire plate from the bolt, placing it carefully to the side.

Set aside the old battery terminal, and replace it with the new one.
Replace the wire plates in the order they were taken off.
Although it is not necessary that the plates be placed in the same order again, it is generally a good idea to go with the order that it came in.

Place the flat washer and the screw-on head that came with the battery terminal onto the vertical bolt.
Tighten the head clockwise and make sure the wire plates are secured.
Not all battery terminal packs come with a washer and screw-on head. If your pack comes with a nut, use the wrench and tighten the bolt clockwise.

Using a rag, place the positive terminal back onto the positive node.

Place the negative terminal back onto the negative node.

On the negative terminal, use the wrench to rotate the side nut clockwise to tighten it.
Next, perform the same action on the side nut of the positive terminal.
To ensure a secure connection, be sure the nut is snug and that the terminal can't come off easily.

Guide content belongs to iFixit, license CC BY-NC-SA. Open original