Things You Will Need- Protective eye wear
- A plastic funnel
- A battery Hydrometer
- A Battery post/terminal cleaner
- A screwdriver
- A Volt Meter with probes
- A Battery Load tester 100 amps
- Battery Treatment (optional)
- A 6/12-Volt Battery Charger/Starter
Step 1Place the battery post cleaner on the negative post and turn it several times until the wire brushes completely clean the post. Repeat for the negative post.
Step 2Use the voltmeter to check the battery voltage. Place one probe on the positive terminal and the other on the negative and read the voltage. If the battery is not holding at least 12 volts there is a problem with at least one cell.
Step 3Remove the cell covers; you may need to use a screwdriver for this.
Step 4Check the voltage of the first cell, start with the one closest to the positive post. All cells should read 2 volts or the cell is weak or bad. To check the first cell; place one probe on the positive post and place the other probe in the first cell.
Step 5Check the other cells, they too should read 2 volts each. Place one probe in the first cell and the other probe in the second. For the third cell, place one probe in the second cell and the and the other probe in the third cell. Repeat for all cells.
Step 6Do a battery load test. Connect the load tester to the positive post first then to the negative (doing the connection in this order prevents sparks). Switch on the load tester and check that the voltage doesn't drop below the yellow area (below 10 or so volts).
Step 7Hydrometer test. The hydrometer is a glass tube with a glass bulb on the end that is used to draw electrolyte from the battery to test the liquids charge level. Take the hydrometer in hand and squeeze the bulb before you insert it into the first cell. Release the bulb to draw in the electrolyte; be careful not to spill the liquid. Note the color of the section of the float that's at the surface; check the color against the list below. Return the liquid to the cell and repeat for the other cells.
- Floats to the green - the battery is in good shape
- Floats to the white - the battery is in fair shape
- Floats to the red - the battery really needs a charge
Also check that each cell has enough electrolyte to cover the cells. The liquid electrolyte should cover the lead plates by at least an eight of an inch.
Step 8Optional - If the batter is in good shape, it is time to add the battery treatment chemicals. Follow the instruction provided by the chemical manufacturer.
Step 9Replace the cell caps and place the battery on the charger for approximately 24hours.
If all goes well, you car battery should be holding a charge and will be ready for use. Otherwise you may need to go buy another battery. Here is a video showing the entire process.
Tips & Warnings- Always wear protective eye wear and clothing, when working with batteries; battery acid can cause severe burns.
- Cleanup any liquid that spills from the battery.
- Never work on batteries near open flames or while smoking. The gas from the battery can explode.
- Always connect the positive terminal first and disconnect it last: this will prevent sparks.