Fix Sluggish Starters

September 28, 2010


Got a lazy starter? Don't just replace the battery. Compare two voltage drops to pinpoint the problem's cause.



Fix Sluggish Starters

  1. Measure voltage across the battery terminals while cranking the engine. A 12-volt battery should make at least 9.5 volts—a 24-volt battery 19 volts.
  2. Measure voltage across the starter posts while cranking the engine. Battery voltage and starter voltage should be within 0.5 volt.

If voltages are both low, charge the battery.

If voltages are different, clean the cables.*

If voltages are the same, replace the starter.

*NOTE: If the voltages are different, move the black volt-meter lead to ground and test once more. If voltage rises, clean the ground circuit of the starter. If the voltage remains low, clean the battery ground, the battery positive, and the starter positive.

Source: Dan Sullivan, Sullivan Training Solutions,