2004 John Deer Buck Utility ATV 500, 500EX and 500EXT Service Manual, Page 153Get this manual
multimeterSTATIC TEST: Unplug the magneto connectorMeasure the resistance between the proper wiresThe obtained value should be between 190 and 300 WMagneto Connector Wires BlackYellow and Yellow With multimeter, voltage readings appear instantly to show the state of chargeAlways respect polarityA fully charged battery will have reading of 12.6 VdcA hydrometer more accurately measures the charge of battery in terms of specific gravity of the electrolyteA fully charged battery will have specific gravity between 1.265 to 1.280 If the resistance is out of specifications, change the trigger coil
Symptom: Discharged or Weak Battery CAUSE Battery posts andor cable terminal oxidizedLoose or bad connectionsREMEDY Clean and coat with dielectric greaseCheck wiring and connector cleanliness, damaged or short circuitReplaceA17E0JA
A17e0ja2.EPS
A hydrometer measures the charge of battery in terms of specific gravity of the electrolyteMost hydrometers give true reading at 21C (70F)In order to obtain correct readings, adjust the initial reading by adding 0.004 points to the hydrometer readings for each 5.5C (10F) above 21C (70F) and by subtracting 0.004 point for every 5.5C (10F) below 21C (70F)This chart will be useful to find the correct readingElectrolyte Temperature 38 32 27 100 90 80 70 60 50 40 30 add .012 .008 .004 correct reading subtract .004 .008 .012 .016 from the reading to the reading Operation To Perform