Maintenance and Repairing of Electrical System Equipment Part

Maintenance and Repairing of Electrical System Equipment: Part 4

Lecturing 06 Quiz n Explain principles of maintenance and repair to generator and AC/DC electrical motor.

Pre Lecturing 07 Quiz Explains principles of maintenance and repair of Batteries of different types! n Explains principles of maintenance and repair of converters, rectifiers and Backup-UPS! n Explains principles of maintenance and repair of Electric tank content measuring systems! n Explains principles of maintenance and repair of electrical diagnostic systems for testing diesel engine! n

Batteries n Why Marine Batteries Fail – When a lead-acid battery is discharged, a soft lead sulfate material forms on the battery plates. During the battery's recharge, this material is lifted off the plates and recombined into the battery's electrolyte solution. If, however, the battery is left in a partial state of discharge for as short as 3 days, the lead sulfate material will begin to harden and crystallize, forming a permanent insulating barrier. As this barrier becomes thicker and thicker, the battery's ability to accept a charge or deliver energy is diminished, resulting in the perception that the battery is no longer usable. The accumulation of such deposits, otherwise known as sulfation, is the most destructive process in the life of any lead-acid battery.

Determining Battery State of Charge attery state of charge is determined by reading either terminal voltage or the specific gravity of the electrolyte. n The density or specific gravity of the sulfuric acid electrolyte of a leadacid battery varies with the state of charge (see table below). Specific gravity is read with a hydrometer. A hydrometer reading will tell the exact state of charge. A hydrometer cannot be used with sealed, AGM or gel cell batteries. n Voltage meters are also used to indicate battery state of charge. Digital voltmeters provide the accuracy to read the voltage in hundredths and are relatively inexpensive and easy to use. The main problem with relying on voltage reading is the high degree of battery voltage variation through out the day. Battery voltage reacts highly to charging and discharging. As a battery is charged the indicated voltage increases and, as discharging occurs, the indicated voltage decreases. With experience, one can accurately determine state of charge using a voltmeter. n

Battery State Of Charge Reference Chart Source: https: //www. emarineinc. com/Marine-Batteries-Maintenance-101

Monitoring and Maintenance n The battery voltage should be kept at or above a 50% state of charge for maximum battery life. Keep the battery's electrolyte level to the indicated level and never let the plates be exposed above the electrolyte. Use only distilled water - not tap water, when refilling the batteries. Water is the only element used by your battery. You should never have to add acid to your battery. Do not overfill or fill when the batteries are discharged. Over-watering dilutes the acid excessively and electrolyte will be expelled when charging.

Equalization is the controlled overcharging of a fully charged battery. This overcharge mixes the electrolyte, evens the charge among varying battery cells and reduces permanent sulfation of the battery plates. It is energy invested in lengthening the life of the battery. We believe that as a rule of thumb, equalization should be done every 60 to 90 days. n Equalization will take your batteries to 15 volts or higher (30 volts on a 24 -volt system), so make sure any DC loads are disconnected before you begin. The equalization process consumes water and produces gassing. Make sure your batteries are well ventilated during this charging. The batteries should be monitored closely during this process. Check specific gravity of all the cells at the start, noting any low cells. Keep checking electrolyte density during the process, until you receive three readings of 30 minutes apart that indicate no further increase of specific gravity values. n The fumes produced during Equalization can be very destructive to fabric and upholstery if the batteries are located in the living area of a boat. The area needs to be well ventilated. n

Battery conditioners (desulfator) are an alternative to equalization. Battery conditioners use a sweeping pulse of energy emitted into a battery bank that eliminates and prevents this life limiting process. The frequencies at which these pulses are emitted are tuned to excite the structural components of the sulfate deposits. This process enables sulfation to revert back in to the electrolyte. n Battery Protectors can save replacing your house battery bank and provide the best insurance policy for small price. Battery protectors sit between the battery bank and your house loads. If for some reason you should draw down your battery below the preset level (typically 10. 5 V), the battery protector will disconnect the loads saving the battery bank. n Typically refrigeration is left on board when you leave the boat draining your batteries down causing you to lose your battery bank and ultimately be food in the refrigerator. The battery protector would disconnect the refrigerator saving the house battery bank, but yes you will still have bad food in refrigerator. n

References to read n https: //www. emarineinc. com/Solar-PV- System-Control-Safety-For-Boats n https: //www. emarineinc. com/Battery. Isolators-Low-Cost-Is-Not-High-Quality n https: //re-tron. com/batteries/5 -tips/