ent. Bacterial growth in diesel fuel can be an issue in warm climates. Consult the generator set manufacturer or dealer for recommendations on treating stored fuel with a biocide. Regular testing and fuel polishing may be required if the fuel is not used and replenished in three to six months.
The charge-air cooler piping and hoses should be inspected regularly for leaks, holes, cracks, or loose connections. Tighten the hose clamps as necessary. In addition, inspect the charge-air cooler for dirt and debris that may be blocking the fins. Check for cracks, holes, or other damage.
The engine air intake components should be checked at the interval indicated in the Table. The frequency of cleaning or replacing air cleaner filter elements is primarily determined by the conditions under which the generator set operates. Air cleaners typically contain a paper cartridge filter element that can be cleaned and reused if not damaged.
Weak or undercharged starting batteries are a common cause of standby power system failures. Even when kept fully charged and maintained, lead-acid starting batteries are subject to deterioration over time and should be replaced approximately every 24 to 36 months — or when they no longer hold a proper charge. NiCad starting batteries require less maintenance than lead-acid and are often used in mission-critical applications. However, they are also subject to deterioration and need to be regularly tested under load. See the Table for the recommended inspection interval for lead-acid batteries and the charging system.
• Testing batteries: Merely checking the output voltage of the batteries is not indicative of their ability to deliver adequate starting power. As batteries age, their internal resistance to current flow goes up, and the only accurate measure of terminal voltage must be done under load. On some generators, this diagnostic test is performed automatically each time the generator is started. On other generator sets, use a manual battery load tester to verify the condition of each starting battery.
• Cleaning batteries: Keep the batteries clean by wiping them with a damp cloth whenever dirt appears excessive. If corrosion is present around the terminals, remove the battery cables and wash the terminals with a solution of baking soda and water (¼ lb baking soda to 1 quart of water). Be careful to prevent the solution from entering the battery cells, and flush the batteries with clean water when finished. After replacing the connections, coat the terminals with a light application of petroleum jelly.
• Checking specific gravity: In open-cell lead-acid batteries, use a battery hydrometer to check the specific gravity of the electrolyte in each battery cell. A fully charged battery will have a specific gravity of 1.260. Charge the battery if the specific gravity reading is below 1.215.
• Checking electrolyte level: In open-cell lead-acid batteries, check the level of the electrolyte at least every 200 hr of operation. If low, fill the battery cells to the bottom of the filler neck with distilled water.
Generator set exercise
Generator sets on continuous standby must be able to go from a cold start to being fully operational in a matter of seconds. This can impose a severe burden on engine parts. However, regular exercising keeps engine parts lubricated, prevents oxidation of electrical contacts, uses up fuel before it deteriorates, and, in general, helps provide reliable engine starting. Exercise the generator set at least once a month for a minimum of 30 min. loaded to no less than one-third of the nameplate rating. Periods of no-load operation should be held to a minimum because unburned fuel tends to accumulate in the exhaust system. Whenever possible, test the system with actual building loads in order to exercise the automatic transfer switches and verify performance under real-world conditions. If connecting to the normal load is not convenient for test purposes, the best engine performance and longevity will be obtained by connecting it to a load bank of at least one-third the nameplate rat