Give your batteries staying power with proper care
Batteries mystify many people. Why do some batteries last for years, while others go bad in a short time? When one is dead, how can you determine whether the problem lies in the battery or some other area of the electrical system? Simple techniques help you quickly and accurately make this determination. But proficiency with batteries goes beyond the ability to determine whether to replace one. Just like other equipment components, batteries require proper maintenance and storage.
Batteries used in outdoor power equipment are usually lead-acid storage batteries that provide power through a chemical reaction between the lead plates in each cell and the electrolyte solution surrounding these plates (see photo, at left). Some batteries allow you to add water through removable vent caps while others are sealed, providing a "maintenance-free" battery. The battery type determines how much servicing you can do to it.
Safety concerns Before you do any service work to a battery, be aware of the potential dangers. Following the safety guidelines outlined below and those provided in your equipment operator's manual will ensure your safety and the continued serviceability of the battery.
* Batteries contain sulfuric acid. Always wear eye, face and hand protection when working with batteries.
* Batteries produce potentially explosive gases. Keep all sparks, open flames and cigarettes away from the battery.
* Make sure your work area is well-ventilated.
* Do not lean or work directly over a battery that you are boosting or charging.
* Keep removable vent caps securely in place except when servicing the electrolyte solution.
* Inspect the battery for and visible damage before doing any service work.
Voltage testing A battery performs three jobs during normal operation: It starts the equipment, provides power during periods of peak demand and stores power from the charging system during periods of low demand. You can see this happen by connecting a digital voltmeter to the terminals. By setting the meter on "DC volts" and placing the red lead on the positive (+) terminal post and the black lead on the negative (-), you can get a reading under these different conditions.
Taking a voltage reading before starting a piece of equipment will show you the battery's "open-circuit voltage" and a corresponding indication of the battery's state of charge. Voltage for a 12-volt battery should be about 12.6 volts. This is a fixed value for a six-cell battery determined by the ratio of water and sulfuric acid in the electrolyte solution. Voltage readings may be slightly over or under this depending on the electrolyte strength (see top photo, page 68).
Now start the engine and run it at a high idle. The voltage reading should be higher than the reading taken with the equipment off. This reading reflects the equipment's charging system as well as the battery's ability to receive a charge during operation. A range from 13 to 15 volts indicates the charging system is functioning correctly. A lower reading could indicate a charging problem.
With the engine operating at idle and the headlights or other electrical devices turned on, take another reading. This can confirm charging problems and show the battery at work providing make-up power for the system. The voltage will drop slightly as the charging system works to provide current to the loads. Battery voltage will probably still be in the 13- to 15-volt range and 0.5 volts or so lower than the previous reading.
These tests indicate how a battery and charging circuit perform during operation, but cannot say much about the battery's ability to do the hard work of starting the engine. However, a battery load test will. A battery load tester simulates the load put on the battery while cranking the engine. You can purchase a relatively inexpensive "toaster-type" load tester from your local automotive tool supplier (see bottom photo, page 68). Follow the instructions from the manufacturer to perform the load test using the load tester.
Actually cranking the engine-with the ignition disabled or the fuel shut off-also can simulate the load test. This test should provide a voltage value s imilar to a load test reading using the load tester (see box, below). If this test gives results that indicate a borderline or questionable battery, have the battery tested by an equipment dealer with a more sophisticated tester to get more precise results.
Battery failure Batteries that are serviced and maintained properly will last a long time, but not forever. Though batteries fail due to normal wear and tear, abuse can greatly shorten their life. If you have a battery that you think failed prematurely, ask yourself some of the following questions.
* Was the battery being used in the application it was intended? For example, replacing a golf-cart battery with an automotive battery will surely end in battery failure due to incorrect application. A golf-cart battery needs to be a deep-cycle battery, a design feature that allows for states of deep discharge and recharge.
* Was the battery sized properly for the application? Your operator's manual will give the cold cranking amp (CCA) requirements for the battery in your equipment. Replacing the battery with a lower value CCA may be less expensive, but will not deliver the amperage necessary when the starting load gets heavy such as in winter.
* Have you added more electrical equipment to the system? Extra lights, fans or other loads may exceed the original equipment's output capacity.
* Was the battery relocated to an area of high heat? Damage to the battery case may result in loss of electrolyte solution. High heat can cause evaporation of water from the battery and limit its performance. severely sulfated (see "Long-term storage," below).
Servicing Batteries operate in a fairly hostile environment and need some care to ensure their longevity. Remember to use good safety practices when servicing your battery. It is often necessary to remove the battery for cleaning or servicing. First, remove the ground cable. This will prevent sparks from the accidental contact of the positive terminal or wire to ground. When the negative terminal is disconnected, you can safely remove the positive cable and battery hold-down clamps. Carefully remove the battery from the battery-mounting bracket.
After you've removed the battery, clean the exterior with a brush and a weak mixture of water and baking soda. This will neutralize any acid that has vented from the battery during operation and will loosen any stuck-on debris. It is worthwhile to note that cleaning the exterior of the battery will help eliminate unwanted current flow between the battery terminals. This current flow can drain the charge from a battery over time.
After you've neutralized the battery, you can clean it with a degreaser to remove any grease or dirt that may remain. After degreasing, flush with clean water.
Now that the battery is clean and there is less risk of getting contaminants into the battery, remove the vent caps and check the electrolyte level. The electrolyte level should be 0.25 to 0.50 inch over the top of the plate separators. Do not overfill! If it is necessary to increase the electrolyte level, add only distilled water. Securely replace the caps. Maintenance-free batteries do not have removable caps and are not serviceable in this way.
When the battery (and battery-mounting area) is clean, reinstall the battery. Inspect the cables, and clean the cable ends with a wire brush or a cable-cleaning brush. You also can clean the battery posts at this time. Put the cables on, taking care not to hammer on the battery post. This may cause the welded connection inside the battery to break, or the plates to short together. You can't repair this damage and will have to get a new battery. If you loosen the clamping bolt and open the clamp to the necessary size, you won't need a hammer. Tighten the clamps securely and replace the positive terminal cover, if so equipped. Coating positive terminals with a terminal spray coat helps to prevent corrosion over time.
Long-term storage Storing a battery incorrectly can seriously affect its condition. Some simple steps will help the battery return to service in peak condition.
Charge the battery before storing it and keep the battery fully charged during the storage period. A battery's electrolyte solution gets weaker as the battery's charge gets lower, making it more likely that the battery could freeze during cold weather. A battery that is 100 percent charged can resist freezing at temperatures close to -70 degrees F, but a battery that is 25 percent charged can only resist freezing down to about +5 degrees F. Keeping your batteries at least 75 percent charged will minimize the danger of freezing.
A battery left in a state of discharge not only is in danger of freezing but also may be subject to sulfation. Sulfation is the formation of deposits on the lead plates during periods of discharge. A slow charge often can remove these deposits if they are not too excessive. However, excessive sulfation will damage the battery beyond repair and require replacement.
Cleaning the battery helps to minimize discharge problems. Corrosion or dirt on the top of the battery encourages current to flow across the top of the battery and decreases the charge. You can measure this "case leakage" by putting the red and black leads of your multimeter on the plastic case next to the (+) and the (-) terminals. Any voltage reading on the meter will indicate a battery drain. Cleaning and neutralizing the top of the battery should minimize or eliminate any problems.
Storage location is an area of concern as well. Keep the battery in a cool, dry place where temperature variations are not extreme. A cool storage place will help maintain the battery's charge.
Performing the maintenance of a lead acid battery can be fairly easy. Following the procedures I've outlined in this article for testing, cleaning, charging and storing of your battery will help ensure that your equipment works when you need it.
Douglas Hammond is assistant professor at the State University of New York-Cobleskill.
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