Battery Types and Sizes

Battery Connections Connections to battery posts must be made with permanent connectors that provide a reliable, low-resistance connection. Do not use alligator clips. Clean the connections regularly and prevent corrosion by using a protective spray coating or Vaseline.

Battery State of Charge You can measure battery state of charge with a hydrometer or approximate state of charge with a voltmeter. Use a digital voltmeter that can display tenths or hundredths of a volt when measuring 10 to 30 volts. Make your measurements when the battery has not been charged or discharged for several hours. For a deep-cycle battery at 77º F (25º C), use the following table:

Battery Voltage State of Charge

12.7–13.0 100%

12.5–12.6 80%

12.3–12.4 60%

12.1–12.2 40%

11.9–12.0 20%

B–8