How to Check for a Shorted Battery Cell
Automotive batteries contain a mixture of water and sulphuric acid in each cell. The mixture of these two substances travels around metal plates to energize the cells and transmit electrical current. A battery that begins to loose power and needs repeated charging may have a shorted cell that does not allow the fluids to move. Sulphuric acid sticks to the plates and will not allow the cell to produce amps or volts for starting and running the car.
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Things You'll Need
- Battery charger
- Flat-tip screwdriver
- Gloves
- Safety glasses
- Hydrometer
- Paper and pen
Instructions
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1
Turn the car off and place it in park.
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2
Place a battery charger near the car or on top of the fan shroud. The fan shroud is the plastic cover surrounding the cooling fan behind the radiator.
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3
Squeeze the red alligator clip on the battery charger and place it on the positive (+) battery terminal. Release the clip so it stays on top of the terminal. Repeat this procedure to attach the black clip on the car frame. Turn the battery charger on and plug it into an electrical receptacle or an extension cord. Switch the charger to the 6- or 12-volt setting that is on the battery label. Allow the charger to charge the battery fully. Turn the charger off and remove the clips from the car.
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4
Let the battery sit for 30 minutes to stabilize the charge among the cells.
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Put gloves and safety glasses on.
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Slide a flat-tip screwdriver under the cap on each battery cell and pry them all off. Squeeze the bulb on the top of a hydrometer and insert the tip barely into one battery cell. Release the bulb to suck battery fluid into the hydrometer.
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Turn the hydrometer upside down, holding the tip up and the bulb down. Read the hydrometer to determine the proportion of water to sulphuric acid in the battery cell. Take the reading at the bottom straight line in the tool and do not include the sides that bubble up in the glass. The reading should fall between 1.215 and 1.28. Check each cell and write the reading down on paper with a pen. A difference in the hydrometer reading of .05 lower than the other cells indicates a shorted cell or a reading in any cell below 1.215. In either case, the battery needs to be replaced.
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Replace the battery caps on each cell and press them down firmly to seal the battery.
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Tips & Warnings
Do not touch or go near the battery while it is charging. Batteries emit hydrogen gas when they are charging.
References
- Photo Credit dead battery image by Katrina Miller from Fotolia.com
