BATTERY If time is available, the lower  charging  rates  in  amperes are recommended. While battery is being charged, periodically measure the temperature    of    the    electrolyte.        If    the    temperature exceeds   51   .6°C   (1   250F)   or   if   violent   gassing   or spewing of electrolyte occurs, the charging rate must be reduced  or  temporarily  halted.    This  must  be  done  to avoid damage to the battery. NOTE - DO NOT OVERCHARGE batteries, particu- larly maintenance free type batteries.  Overcharging causes excessive and needless loss of water from the electrolyte. Figure 14 - Charging Battery SLOW CHARGING The Slow Charge method uses a low charging rate for a relatively long period of time.  The recommended ratefor slow charging is one ampere per positive plate per cell. If the battery has nine plates per cell, normally four of the nine will be positive plates.  Therefore, the slow charge rate would be four amperes.  Charging periods as long as twenty-four hours may be needed to bring a battery to full charge. The best method of making certain a battery is fully charged, but not overcharged, is to measure the specif- ic gravity of a cell once per hour.  The battery is fully charged when no change in specific gravity occurs over a three hour period or when charging current stabilizes (constant voltage type charger). If   low   maintenance   (conventional)   battery   is   to   be charged overnight (10-16 hours) use the specified Slow Charge rate (Table 6). Maintenance free batteries must not be charged at rates greater  than  specified  in  the  Maintenance  Free  Battery Charging Guide (Table 7). If  a  maintenance  free  battery  is  to  be  recharged  over- night (16 hours), a timer or voltage controlled charger is recommended.  If the charger does not have such con- trols, a 3 ampere rate should be used for batteries of 80 minutes or less capacity and 5 amperes for above 80 to 125  minutes  reserve  capacity  batteries.    Batteries  over 125  minutes  should  be  charged  at  the  specified  Slow Charge rate (Table 7). Batteries that have stood in a discharged condition for long periods of time without a recharge have become sulfated and must be recharged at a low rate to avoid overheating and excessive gassing.  It may require two or three days of slow charging to bring a sulfated battery to a fully charged condition.  Care should be taken not to overcharge maintenance free type batteries. Some  batteries  are  so  badly  sulfated  they  cannot  be restored  to  a  normal  operating  condition,  regardless  of the  rate  of  charge  or  the  length  of  time  the  charge  is applied.  Therefore, if a battery cannot be restored to a fully  charged  condition  by  slow  charging,  it  should  be rejected. FAST CHARGING The Fast Charge method provides  a  high  charging  rate for a short period of time.  The charging rate should be limited  to  60  amperes  for  12-volt  batteries.    Maximum charging  rate  for  6-volt  batteries   (above   180   reserve capacity   miniutes)   can   be   approximately   double   this value. Ideally,  fast  charges  should  be  limited  to  the  charging times shown under Fast Charge in the Battery Charging Guides, Tables 6 and 7.  The battery generally cannot be fully charged within these time periods, but will re- ceive sufficient  charge  (70  to  90%)  for  practical  service.  To completely recharge a battery, follow the fast charge with a slow charge until no change in specific gravity occurs over'a three hour period. A  battery  with  electrolyte  specific  gravity   of   1.225   or above  should  never  be  charged  at  a  high  rate.    If  the charger  has  not  tapered  to  a  low  rate,  adjust  to  a  slow charge,  preferably  at  a  rate  of  one  ampere  per  positive plate per cell. CHARGING INSTRUCTIONS Before  placing  a  battery  on  charge,  clean  the  battery terminals  if  necessary.    Add  distilled  water  sufficient  to cover the plates.  Fill to the proper level near the end of charge.  If the battery is extremely cold, allow it to warm before  adding  distilled  water  because  the  level  will  rise as  it  warms.    In  fact,  an  extremely  cold  battery  will  not accept a normal charge until it becomes warm. Following instructions  of  charger  manufacturer,  con-  nect  charger to battery. CTS-4111B - Page 13