Car Battery Repair: When to Fix and When to Replace
Car batteries are made of lead plates separated by a water and sulfuric acid solution called electrolyte, and some problems that arise with these components can be fixed while others cannot. You should research car battery repair before you decide to try to fix your vehicle's battery. There is no such thing as a car battery repair kit, so you will have to collect the necessary materials yourself, including hand and eye protection, a screwdriver, a hydrometer, a hand-held multimeter and distilled water. The following car battery repair guide will give you all the information you need to determine whether you can repair the battery or you need to replace it.
To check the electrolyte levels in a car battery, you can remove the battery caps on each of the electrolyte cells. If they are not full, top them off with distilled water. Use a hydrometer to measure the sulfuric acid concentration in each cell. It should read about 1.215 to 1.28, and any reading below 1.175 indicates that sulfation, the process of sulfuric acid breaking down into other chemicals, has occurred and the battery needs to be replaced.
Using the Multimeter
Use a multimeter with both leads connected to the corresponding terminals on the battery to determine the battery's output. With the battery fully charged and the car off, the voltmeter should read between 12.6 and 12.8 volts. Turn on the car and take another reading. This time it should be around 10 volts. If these measurements are off, there is nothing you can do to repair the battery and it needs to be replaced.