Checking the condition of the battery by testing the state of charge. VISUAL INSPECTION O  F     T  H  E BATTERY.—Battery    maintenance    should    always begin  with  a  thorough  visual  inspection.  Look  for  signs of corrosion on or around the battery, signs of leakage, a  cracked  case  or  top,  missing  caps,  and  loose  or missing  hold-down  clamps. CHECKING   ELECTROLYTE   LEVEL   AND ADDING  WATER.—On    vent    cap    batteries,    the electrolyte level can be checked by removing the caps. Some  batteries  have  a  fill  ring  which  indicates  the electrolyte  level.  The  electrolyte  should  be  even  with the  fill  ring.  If  there  is  no  fill  ring,  the  electrolyte should be high enough to cover the tops of the plates. Some  batteries  have  an  electrolyte-level  indicator (Delco Eye). This gives a color code visual indication of the electrolyte level, with black indicating that the level is okay and white meaning a low level. If the electrolyte level in the battery is low, fill the cells  to  the  correct  level  with  DISTILLED  WATER (purified   water).   Distilled   water   should   be   used because it does not contain the impurities found in tap water. Tap water contains many chemicals that reduce battery life. The chemicals contaminate the electrolyte and collect in the bottom of the battery case. If enough contaminates collect in the bottom of the case, the cell plates  SHORT  OUT,  ruining  the  battery. If  water  must  be  added  at  frequent  intervals,  the charging  system  may  be  overcharging  the  battery.  A faulty charging system can force excessive current into the  battery.  Battery  gassing  can  then  remove  water from the battery. Maintenance-free batteries do NOT need periodic electrolyte  service  under  normal  conditions.  It  is designed  to  operate  for  long  periods  without  loss  of electrolyte. C L E A N I N G    T H E    B A T T E R Y    A N D TERMINALS.—If   the   top   of   the   battery   is   dirty, using a stiff bristle brush, wash it down with a mixture of  baking  soda  and  water.  This  action  will  neutralize and  remove  the  acid-dirt  mixture.  Be  careful  not  to allow cleaning solution to enter the battery. To  clean  the  terminals,  remove  the  cables  and inspect the terminal posts to see if they are deformed or broken.   Clean   the   terminal   posts   and   the   inside surfaces of the cable clamps with a cleaning tool before replacing them on the terminal posts. CAUTION Do  NOT  use  a  scraper  or  knife  to  clean battery   terminals.   This   action   removes   too much   metal   and   can   ruin   the   terminal connection. When  reinstalling  the  cables,  coat  the  terminals with  petroleum  or  white  grease.  This  will  keep  acid fumes  off  the  connections  and  keep  them  from corroding  again.  Tighten  the  terminals  just  enough  to secure  the  connection.  Overtightening  will  strip  the cable bolt threads. CHECKING  BATTERY  CONDITION.— When   measuring   battery   charge,   you   check   the condition of the electrolyte and the battery plates. As a battery becomes discharged, its electrolyte has a larger percentage   of   water.   Thus   the   electrolyte   of   a discharged  battery  will  have  a  lower  specific  gravity number than a fully charged battery. This rise and drop in specific gravity can be used to check the charge in a battery.  There  are  several  ways  to  check  the  state  of charge of a battery. Nonmaintenance-free batteries can have the state of charge checked with a hydrometer. The hydrometer tests specific gravity of the electrolyte. It is fast and simple to use.  There  are  three  types  of  hydrometers—the  float type, the ball type, and needle type. To use a FLOAT TYPE HYDROMETER, squeeze and hold the bulb. Then immerse the other end of the hydrometer  in  the  electrolyte.  Then  release  the  bulb. This  action  will  fill  the  hydrometer  with  electrolyte. Hold the hydrometer even with your line of sight and compare the numbers on the hydrometer with the top of the  electrolyte. Most float type hydrometers are NOT temperature correcting. However, the new models will have a built- in thermometer and a conversion chart that allow you to  calculate  the  correct  temperature. The  BALL  TYPE  HYDROMETER  is  becoming more  popular  because  you  do  not  have  to  use  a temperature  conversion  chart.  The  balls  allow  for  a change in temperature when submersed in electrolyte. This allows for any temperature offset. To  use  a  ball  type  hydrometer,  draw  electrolyte into  the  hydrometer  with  the  rubber  bulb  at  the  top. Then   note   the   number   of   balls   floating   in   the electrolyte. Instructions on or with the hydrometer will tell   you   whether   the   battery   is   fully   charged   or discharged. 2-8