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Battery Maintenance

Summer heat and winter cold are your batteries worst enemies. A little maintenance will go a long way to insure you vehicle will start even in the worst of conditions.

Your vehicles battery is subjected to a wide range of adverse conditions. Extreme heat and cold, alternator undercharging or overcharging all take their toll on your battery. Yet the only time we think about it is when we get in the car and all we hear is a loud clicking or buzzing when we try to start the engine. So we get out the jumper cables and get going to work or the mall. But when we set out to go home, we hear the same noises. Now is the time we do some hard thinking about the battery.

How is the Battery constructed…?

A 12-volt lead-acid battery is made up of six cells, each cell producing approximately 2.11 volts that are connected in series from POSITIVE (+) terminal of the first cell to the NEGATIVE (-) terminal of the second cell and so on. Each cell is made up of an element containing positive plates that are all connected together and negative plates, which are also all connected together. They are individually separated with thin sheets of electrically insulating, porous material "envelopes" or "separators" that are used as spacers between the positive (usually light orange) and negative (usually slate gray) plates to keep them from electrically shorting to each other. The plates, within a cell, alternate with a positive plate, a negative plate and so on.

The most common plate in use today is made up of a metal grid that serves as the supporting framework for the active porous material that is "pasted" on it. After the "curing" of the plates, they are made up into cells, and the cells are then inserted into a high-density tough polypropylene or hard rubber case. The positive plates in the cells are connected in parallel to the external POSITIVE (+) terminal and the negative plates in each cell are connected to the NEGATIVE (-) external terminal. Instead of pasted Lead Oxide, some batteries are constructed with more expensive solid lead cylindrical shape (spiral wound); Manchester or "Manchex" (buttons inserted into the grid); tubular; or prismatic (flat) solid lead (Planté) positive plates. The case is covered and then filled with a dilute sulfuric acid electrolyte.

The battery is initially charged or "formed" to convert the active yellow Lead Oxide (PbO or Litharge) in the positive plates (cathode) into Lead Peroxide (PbO2), which is usually dark brown or black. The active material in the negative pasted plates (anode) becomes sponge Lead (Pb), but with a very porous structure which is slate gray. The electrolyte is replaced and the battery is given a finishing charge. A "Wet charged" battery is a wet lead-acid battery shipped with electrolyte in the battery and a "dry charged" battery is shipped without electrolyte. When dry charged batteries are sold, electrolyte (battery acid) is added, allowed to soak into the plates, charged (or "formed"), and put into service. This avoids having to maintain the batteries until they are sold.

This is probably more than you need to know but I have to do something to justify all the money I spent on education and training classes.

While working with car and deep cycle lead-acid batteries (and corrosion), please wear protective glasses to protect your eyes from sulfuric acid splashes and the unlikely event of an explosion.

How To Test The Battery: Voltage…

The first, basic, test is battery voltage. With a voltmeter check the voltage across the battery terminals. Make sure the key is OFF and any battery-operated items are off as well. You should have 12.5 to 12.6 volts across the battery terminals. 12 volts is acceptable if the battery is not fully charged but will turn over and start the engine. If voltage is less than specified, we need to go on to the next test.

With the engine running and with a properly operating charging system and fully charged battery, the voltage should be about 14.6 volts.

How To Test The Battery: Specific Gravity…

The next test is the "State Of Charge" (SoC). For this we will need a battery hydrometer. They are very inexpensive and you can get them at any parts store or Wal-Mart. I would avoid the 'balls' type and get the 'float' type; they are much easier to read. A battery hydrometer measures the proportion of sulfuric acid to water, which is a precise measure of the level of charge.

First remove the cell caps and check the electrolyte level. The level should be just at the level of the cell hole. If it isn't you will need to top it off. Ideally you should use distilled water. In a pinch you can use rainwater since it is cleaner than tap water and does not contain chlorine, calcium or magnesium. Using Reverse Osmosis (RO) or tap water to refill batteries can produce chlorine gas or calcium sulfate crystals that can fill the pores and coat the plate that reduces the batteries capacity.

How To Test The Battery: Low Or Maintenance Free Batteries

If you have a low maintenance or maintenance free battery there are probably cell caps hidden under the stickers. Lift the stickers up and you should be able to see them. Put the hydrometer hose into the cell and draw enough electrolyte into it to reach the 'full' line.

  • A Couple Of Tips…

Squeeze the bulb before putting it into the electrolyte and when it's full keep the hose in it so you don't dribble and drip the electrolyte all over the paint and your clothes. The acid will eat paint, clothing and skin.

Back To Testing…

The specific gravity of a fully charged cell is 1.265. Additionally, each cell should have close to the same reading. If one cell is lower or higher by 0.05 you have a weak battery and should replace it.

How To Test The Battery: Load Testing…

You will need some special equipment to load test a battery. You can buy a battery load tester at the parts store anywhere from $35.00 for a basic tester to well over $1,000.00 for one with all the bells and whistles. Me? I like bells and whistles. I have the Milton Battery Load Tester that works very well and I have had it for years. Basically you connect the load tester to the battery and hold the load switch. Count 15 seconds and read the meter. It should be in the green zone for a good battery. Don't hold it for more than 15 seconds or you will damage the tester.

If the test ends up in the yellow and it's springtime, you may make it through the summer. If it's in the red zone, buy a new battery.

Battery Maintenance And Care...

Batteries do so much and ask so little, but what they do ask for they insist on. Like you, they like to be clean and need a bath every once in a while. First wash the battery with lots of water. Don't forget to wear your protective glasses. Heavy corrosion can be neutralized with a mixture of one pound of baking soda to one gallon of warm water. Some folks have been known to use Diet Coke or Diet Pepsi to dissolve corrosion. Once the corrosion is cleaned off remove the battery terminals and look at them. Any terminals that are cracked or broken should be replaced. Using a battery brush clean the battery posts and terminals until they are nice and shiny. Bare metal-to-metal mating surfaces are required for good current conductivity. To prevent corrosion on terminals, thinly coat the terminals, terminal clamps and exposed metal around the car battery with high temperature wheel bearing grease or silicone. Gluing a sacrificial anode, such as a penny or a piece of copper to the top of the battery will prevent or reduce terminal corrosion.

One or more of the following causes corrosion:

  • Dirty or wet battery tops normally caused from expansion of electrolyte from overfilled cells or weeping from faulty battery terminal seals
  • Acid fumes leaking through the vent caps, which could be a sign of overcharging
  • Electrolysis due to the mismatch of metal alloys used in the battery posts and terminals

Replace the battery if the battery case is bulging, cracked or leaking, especially around "GM" style side terminals.

I know this looks and sounds like a lot of work, but it's really not. General cleaning should be done once a month or so and testing every three or four months, especially after the second or third year of the batteries life.

Additional Information provided courtesy of
ALLDATAdiy.com and Warranty Direct
© 2000-2007 Vincent T. Ciulla

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