Battery Charging The manufacturer's manual may specify charging procedures for the type of battery you are to charge. If so, follow those procedures.

There are several types of battery charges, but you will generally use a normal charge, an equalizing charge, or a fast charge. We will discuss these three types of charges briefly. For more information on storage or dry-cell batteries and battery charging, refer to the Navy Electricity and Electronics Training Series (NEETS), NAVEDTRA 172-01-00-88 (Module 1).

NORMAL CHARGE.- A normal charge is a routine charge that is given according to the battery nameplate data during the ordinary cycle of operation to restore the battery to its charged condition,

EQUALIZING CHARGE.- An equalizing charge is a special extended normal charge that is given periodically to batteries as part of a maintenance routine. It ensures that all the sulfate is driven from the plates and that all the cells are restored to a condition of maximum specific gravity. The equalizing charge is continued until the specific gravity of all cells, corrected for temperature, shows no change for a 4-hour period.

FAST CHARGE.- A fast charge is used when a battery must be recharged in the shortest possible time. The charge starts at a much higher rate than is normally used for charging. It should be used only in an emergency, as this type of charge may be harmful to the battery.

CHARGING RATE.- Normally, the charging rate of Navy storage batteries is given on the battery nameplate. If the available charging equipment does not have the desired charging rates, the nearest available rates should be used; however, the rate should never be so high that violent gassing occurs.

CHARGING TIME.- The charge must be continued until the battery is fully charged. Frequent readings of specific gravity should be taken during the charge and compared with the reading taken before the battery was placed on charge.

GASSING.- When a battery is being charged, a portion of the energy breaks down the water in the electrolyte. Hydrogen is released at the negative plates and oxygen at the positive plates. These gases bubble up through the electrolyte and collect in the air space at the top of the cell. If violent gassing occurs when the battery is first placed on charge, the charging rate is too high. If the rate is not too high, steady gassing develops as the charging proceeds, indicating that the battery is nearing a fully charged condition.

WARNING A mixture of hydrogen and air can be dangerously explosive. No smoking, electric sparks, or open flames should be permitted near charging batteries.

CHARGING PROCEDURE.- If the instruction manual for the generator set is not available or if it does not give the battery a charging procedure, proceed as follows: Connect the positive battery charger terminal to the positive battery terminal and the negative charger terminal to the negative battery terminal.

Charge the battery at a low rate (about 5 amperes) until the voltage and specific gravity, corrected to 80 F (27 C) remains constant for at least 4 hours. If the temperature of the electrolyte reaches 110 F (43 C), reduce the charging rate or stop the charge until the battery cools. NEVER PERMIT THE TEMPERA-TURE TO EXCEED 115 F (46 C). During the charging, replenish any water lost by evaporation.

Hydrometer A hydrometer is the instrument used to measure the amount of active ingredients in the electrolyte of the battery. The hydrometer measures the SPECIFIC GRAVITY of the electrolyte. Specific gravity is the ratio of the weight of the electrolyte to the weight of the same volume of pure water, The active ingredient, such as sulfuric acid or potassium hydroxide, is heavier than water. Because the active ingredient is heavier than water, the more active the ingredient in the electrolyte, the heavier the electrolyte will be; the heavier the electrolyte, the higher the specific gravity.

A hydrometer is a glass syringe with a float inside it. The float is in a hollow, glass tube, weighted at one end and sealed at both ends, with a scale calibrated in specific gravity marked on the side. The electrolyte to be tested is drawn into the hydrometer by the suction bulb. Enough electrolyte should be drawn into the hydrometer so that the float will rise. Hydrometers should not be filled to the extent that the float rises into the suction bulb. Since the weight of the float is at its base, the float will rise to a point determined by the weight of the electrolyte. If the electrolyte contains a large concentration of the active ingredient, the float will rise higher than if the electrolyte has a small concentration of the active ingredient.

To read the hydrometer, hold it in a vertical position and take the reading at the level of the electrolyte. Refer to the manufacturer's technical manual for battery specifications to find the correct specific gravity ranges. An example of what your manual may say about the specific gravity is that for a fully charged battery the specific gravity should be 1.280 0.005. The manual may tell you to recharge the battery if the specific gravity is less than 1.250.

Always return the electrolyte in the hydrometer to the cell of the battery from which it was taken.

NOTE: Hydrometers should be flushed with fresh water after each use to prevent inaccurate readings. Storage battery hydrometers must not be used for any other purpose.

Perhaps it should be said that adding the active ingredient (sulfuric acid, for example) to the electrolyte of a discharged battery does not recharge the battery. Adding the active ingredient only increases the specific gravity of the electrolyte and does not convert the plates back to active material, and so does not bring the battery back to a charged condition. A charging current must be passed through the battery to recharge it.