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Essential Electrical Test

Disclaimer: This information is provided as an aid. It is correct to the best of our knowledge. Use it under your own risk.

Check battery state of charge  SOC























12.65 100%

12.45 75%

12.24 50%

12.06 25%

11.89 0%

* @ 80° F


Make sure to check after vehicle has been seating for at least 1 Hour to eliminate the presence of surface charge.

Accessory Ground Voltage Drop Test












































Place meter probe at accessory ground bolt or Body frame and top of battery negative post.  With Key On engine off, load the system by turning on lights, high beam and blower motor on high speed.  Voltage drop should not exceed 100Mv (0.100V)

Battery Negative Cable Voltage Drop Test














































Make sure to place meter probes on bolt and on top of battery post.  This will insure test of battery cable and connections.  Disable system to insure engine does not turn ON.  Voltage drop during cranking should not exceed 200Mv (0.200V)

Voltage Drop Test Battery to Alternator Cable












































Place meter probe at the alternator’s output voltage bolt and the other at Battery positive post.  With engine running load the system by turning ON lights, high beam and blower motor.  Raise engine RPM to 2000 RPM.  Voltage drop should not exceed 200Mv.

Checking Alternator Output Voltage























Engine running system loaded and engine at 2000 RPM

Voltage Drop Test On Battery Positive Cable












































One end of the meter probe at starter positive cable bolt and the other probe at Battery positive post.  Check while cranking.  Should not exceed 0.200Mv.

Checking Battery Voltage Drop During Cranking























Minimum Battery Cranking Voltage

9.9 100F

9.8 90F

9.5 60F

9.3 40F

8.9 20F

8.5 0F

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