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SECTION 10 CARE AND MAINTENANCE OF BATTERIES<\/strong> 54. CONSTRUCTION OF LEAD ACID CELLS<\/strong> 55. CONNECTION OF LEAD ACID CELLS<\/strong> 56. ESSENTIAL BATTERY MAINTENANCE<\/strong> CHAPTER 4 – Power Supplies<\/strong> 60. MEASURING THE SPECIFIC GRAVITY<\/strong> 61. MEASURING THE ON-LOAD TERMINAL VOLTAGE<\/strong> 63. BATTERY HAZARDS<\/strong> CHAPTER 4 – Power Supplies<\/strong> 64. MAINTENANCE FREE BATTERIES<\/strong> <\/p>\n","protected":false},"excerpt":{"rendered":" Ogni Stazione Radio di Bordo \u00e8 dotata di un sistema di alimentazione autonomo in grado di garantire il funzionamento degli apparati in caso di guasto e \/o mancanza di tensione elettrica nella Nave. Questo sitema supplementare \u00e8 costituito da batterie tipo piombo-acido che a seconda della combinazione e degli apparati di Bordo possono essere configuarate … Continua la lettura di Batterie di Bordo<\/span>
\n53. LOCATION OF BATTERIES
\n53.1 The location of a battery supplying marine radio
\nequipment should be chosen to ensure that, as
\nfar as practicable, the battery is:
\n>> protected from the elements;
\n>> readily accessible for routine maintenance;
\n>> located reasonably close to the transceiver;
\n>> located as high in the vessel as practicable;
\n>> well ventilated to dissipate the hydrogen gas
\nproduced (if located within a wheelhouse or
\nother compartment, venting to the outside
\nmay be necessary);
\n>> not located with other items of equipment
\nthat could, in heavy weather, fall across the
\nbattery and cause short-circuiting; and
\n>> not located in the same compartment as
\na different type of battery, for example,
\nalkaline cells. \u25c6\u2022<\/p>\n
\n54.1 Lead acid cells have a voltage of 2 volts per
\ncell, regardless of size. Larger size cells will
\nsupply higher current than smaller cells, or the
\nsame current for longer periods. The ability of
\na cell to produce current for a period of time
\nis known as the cell\u2019s capacity and is usually
\nmeasured in ampere-hours (Ah), or with batteries
\ndesigned for motor vehicle use, as \u2018cold cranking
\namps\u2019 (CCA). \u25c6\u2022
\n54.2 A chemical combination of lead and lead peroxide
\nplates and the sulphuric acid in the electrolyte
\n(the liquid solution within the cell), produces
\na voltage difference between the plates. This
\nvoltage difference allows a current to flow through
\nany load, such as a radio, connected across the
\nbattery terminals and is called direct-current or
\n\u2018dc\u2019. \u25c6\u2022
\n54.3 When the acid in the electrolyte or the material in
\nthe plates is used up, the voltage no longer exists
\nand current cannot flow. At this point, the cell is
\nsaid to be discharged or \u201cflat\u201d. \u25c6\u2022
\n54.5 This situation is reversible by passing a current
\nin the opposite direction. This process reverses
\nthe chemical reactions in the cell and is known as
\ncharging.\u25c6\u2022<\/p>\n
\n55.1 Cells may be connected in series, that is, the
\npositive terminal of one cell to the negative
\nterminal of another, to produce higher voltages.
\nThree cells connected in series will give a \u201cbattery\u201d
\nof 3 x 2 volts = 6 volts; six cells connected in series
\nwill give a \u201cbattery\u201d of 6 x 2 volts = 12 volts. \u25c6\u2022
\n55.2 Most modern lead-acid batteries are supplied in
\n6 or 12 volt combinations and may themselves
\nbe connected in series to provide the required
\noutput voltage, for example, two 12 volt batteries
\nconnected in series will produce a voltage of 2 x
\n12 volts = 24 volts. \u25c6\u2022
\n29
\n55.3 Connection of lead-acid batteries in parallel, that
\nis positive terminal to positive terminal, negative
\nterminal to negative terminal, will produce the
\nsame output voltage as a single battery, but
\nthe ability to supply current (capacity) will have
\nbeen lengthened. For example, two batteries
\neach supplying 12 volts with a capacity of 60
\nampere-hours, when connected in parallel
\nwill provide a voltage output of 12 volts with a
\ncapacity of 120 ampere-hours. \u25c6\u2022<\/p>\n
\n56.1 The functioning of radio equipment is dependent
\non power supplied by the battery. If it is to
\nprovide adequate performance in the event of
\nan emergency, regular and careful maintenance
\nis required.
\n56.2 A battery\u2019s service life also depends on the
\nmanner in which it is treated.
\n56.3 To ensure the best performance from a battery
\nit is important that a battery:
\n>> is kept clean, dry and free from terminal
\ncorrosion;
\n>> has the electrolyte kept at the correct level;
\nand
\n>> is kept correctly charged. \u25c6\u2022
\nPositive
\nNegative
\nPositive
\nNegative<\/p>\n
\n3 0 MARINE RADIO OPERATORS HANDBOOK – AUSTRALIAN MARITME COLLEGE
\n57. BATTERY CLEANLINESS
\n57.1 A battery top should be kept clean. A dirty battery
\ntop may hold spilt electrolyte on its surface thereby
\nproviding a path for the electrical current to leak
\naway. It is important to keep the outside surfaces
\nof a battery dry and free of contamination. \u25c6\u2022
\n57.2 Corrosion forming on terminal clamps may
\nseriously affect, or even prevent, the ability of
\nthe battery to supply current. Corrosion will
\nbe evident by the formation of a white-green
\npowder between the battery terminals and the
\nterminal clamps. In this situation, the terminal
\nclamp should be removed and both it and the
\nterminal post cleaned. \u25c6\u2022
\n57.3 To minimise the likelihood of corrosion, terminal
\nposts and clamps should be lightly smeared with
\nVaseline\u2122 or petroleum jelly. \u25c6\u2022
\n58. ELECTROLYTE LEVEL
\n58.1 The level of electrolyte inside a battery is
\nimportant. As a result of the chemical action
\ninside a battery, water is lost. This should be
\nreplaced with distilled or demineralised water.
\n\u25c6\u2022
\n58.2 Seawater must not be used under any
\ncircumstances.
\n58.3 The level of the electrolyte should be maintained
\nat approximately 10 mm above the plates unless
\notherwise specified by the manufacturer. \u25c6\u2022
\n58.4 If the electrolyte level is too high, it may overflow
\nduring charging providing an unwanted discharge
\npath. If the electrolyte is too low, the plates are
\nexposed to the air and permanent damage and
\nloss of capacity may result.
\n58.5 It may be noticed that a battery that is nearing
\nthe end of its useful life will require more frequent
\ntopping-up than has been previously necessary.
\n58.6 Low-maintenance batteries will require infrequent
\ntopping-up. Maintenance-free batteries may
\nrequire none at all.
\n59. CORRECT CHARGING
\n59.1 To provide the best service, a battery must
\nbe correctly charged. Both overcharging
\nand undercharging can seriously affect its
\nperformance. \u25c6\u2022
\n59.2 On small vessels the usual means of charging the
\nradio battery will be an alternator or generator
\nattached to the vessel\u2019s engine. An associated
\nregulator, which reduces the charging current as
\nnecessary, should prevent overcharging.
\n59.3 Vessels that are used frequently (say, several times
\neach week) should have no problem maintaining
\na fully charged radio battery. However, on vessels
\nthat are used relatively infrequently (once every
\nfew weeks), it is likely that during storage even
\na battery that starts as fully charged, will selfdischarge
\nand go flat.
\n59.4 For safety reasons, it is important that the vessel
\nowner is able to determine the general condition
\nof a battery and its ability to supply current over
\na period of time (its capacity). An indication of the
\nlevel of charge in a battery may be obtained by
\neither:
\n>> measuring the specific gravity of the
\nelectrolyte; or
\n>> measuring the on-load terminal voltage. \u25c6\u2022<\/p>\n
\n60.1 The specific gravity, also called the relative density,
\nof the electrolyte (the liquid inside the battery)
\nvaries proportionally with the amount of charge
\nin the battery. It is highest when the battery is
\nfully charged and lowest when the battery is fully
\ndischarged or flat. It follows that the amount
\nof charge in a battery can be determined by
\nmeasuring the specific gravity of the electrolyte.
\n\u25c6\u2022
\n60.2 A simple, inexpensive device called a hydrometer
\nis used to measure specific gravity. \u25c6\u2022
\n(See diagram on Page 31).
\n60.3 In general, for a fully charged battery, the specific
\ngravity should measure about 1.250. Half charge
\nwill be indicated by a reading of 1.200 and fully
\ndischarged by 1.150. All cells in a battery should
\nindicate a similar specific gravity. A variation of
\nmore than about 0.025 will indicate a faulty cell
\nand the battery should be replaced. \u25c6\u2022
\n60.4 Specific gravity readings should not be taken
\nimmediately after topping-up a cell as the added
\nwater will float towards the top of the cell and
\ngive a false reading. Charging for thirty minutes
\nor more after topping-up will mix the electrolyte
\nand allow accurate readings.
\n31
\n60.5 Batteries which have cells where specific gravity
\nreadings fail to rise, or respond poorly to adequate
\ncharging, should be replaced.<\/p>\n
\n61.1 Measurement of the terminal voltage when a
\nbattery is supplying current to a load, such as
\na radio, will also provide an indication of the
\namount of charge in a battery. This measurement
\nis known as the on-load terminal voltage. \u25c6\u2022
\n61.2 For a 12-volt battery, the on-load terminal
\nvoltage should not fall below approximately
\n11.4 volts while transmitting. If the voltage does
\nfall significantly below this figure, the battery
\nrequires charging. If after charging, the on-load
\nterminal voltage still falls significantly below 11.4
\nvolts, it is an indication of a faulty cell and the
\nbattery should be replaced.
\n61.3 Measuring of the off-load (that is, when the
\nbattery is idle) terminal voltage of a battery is a
\npoor indication of its condition. \u25c6\u2022
\n62. LOSS OF CAPACITY
\n62.1 A battery will suffer a gradual loss of capacity
\nduring its life. This is inevitable and the battery
\nshould be replaced when the capacity loss
\nbecomes significant.
\n62.2 Many lead-acid batteries have a commercial life
\nof only two to three years.
\n62.3 However, the useful life of a battery can be
\nconsiderably shortened by:
\n>> operating a battery in a low state of charge for
\nlong periods;
\n>> allowing a battery to stand in a discharged
\nstate for long periods;
\n>> leaving a charged battery for long periods
\nwithout periodic charging; and
\n>> overcharging. \u25c6\u2022<\/p>\n
\n63.1 There are two hazards associated with lead-acid
\nbatteries that ship station operators should be
\naware of:
\n>> the risk of explosion; and
\n>> the risk of chemical burns. \u25c6\u2022
\n63.2 As a result of the chemical process occurring
\nwithin the cells of a battery during charging,
\nHydrogen Gas is produced. When mixed with air,
\nthis can form a highly explosive mixture which can
\nbe ignited by a naked flame, a lighted cigarette, or
\na spark. The spark caused by breaking or making
\nan electrical connection in the vicinity of the
\ncharging battery may be sufficient to ignite the
\nhydrogen-air mixture. Batteries should be located
\nclose to the radio equipment and placed in a well
\nventilated container or locker \u25c6\u2022
\n1.3
\n1.2
\n1.1
\nRECHARGE
\nFAIR
\nGOOD
\nRubber Bulb
\nHollow glass float
\nGlass Barrel
\nScale
\nElectrolyte being
\nmeasured
\nWeight to hold
\nfloat erect
\nRubber hose
\n1.150
\n1.200
\n1.250
\n1.300<\/p>\n
\n3 2 MARINE RADIO OPERATORS HANDBOOK – AUSTRALIAN MARITME COLLEGE
\n63.3 If using metal tools to work on battery connections,
\nextreme care must be taken to ensure that
\nterminals are not short-circuited. \u25c6\u2022
\n63.4 The electrolyte in battery cells contains Sulphuric
\nAcid. It is sufficiently concentrated, particularly
\njust after charging, to damage eyes, skin or clothes
\nif spilt or splashed. Immediate and prolonged
\napplication of running water is recommended to
\nminimise its effect. \u25c6\u2022
\n63.5 It is recommended that eye protection, gloves,
\netc. be worn when a person is carrying out
\nmaintenance on batteries. Batteries should not
\nbe topped-up whilst on charge. \u25c6\u2022<\/p>\n
\n64.1 Maintenance Free: Maintenance free Lead \u2013 Acid
\nor Gel type batteries are becoming increasingly
\navailable to mariners. Users of these types
\nof batteries are recommended to follow the
\nmanufacturer\u2019s guidelines in ascertaining the
\ncondition of the battery before replacement.
\nOn vessels where it is mandatory to carry an
\nindependent emergency means of electrical
\nsupply, for communications equipment, it may
\nalso be a requirement to replace \u2018maintenance
\nfree\u2019 batteries after a short operational
\nperiod of 1 year.<\/p>\n