No-Load Test

No-Load Test:

With the carbon pile "OFF", make connection as shown in image. Close the switch, adjust carbon pile to obtain 10 volts, and compare the RPM, current and voltage readings with those under "Specifications".

Make disconnections only with the switch open. Use the test results as follows:
1. Rated current draw and no-load speed indicates normal starter motor condition.
2. Low free speed and high current draw indicates:
- Too much friction. This can be caused by tight, dirty or worn bearings, or bent armature shaft allowing armature to drag.
- Shorted armature.
- Grounded armature or fields.
3. Failure to operate with high current draw indicates:
- Direct ground in terminal or fields.
- "Frozen" bearings (this should have been determined by hand turning armature).
4. Failure to operate with no current draw indicates:
- Open field circuit.
- Open armature coils.
- Broken brush springs, worn brushes, high insulation between commutator bars or other causes which would prevent good contact between brushes and commutator.
5. Low no-load speed and low current draw indicates:
- High internal resistance due to poor connections, faulty leads, dirty commutator and causes listed above under number 4.
6. High free speed and high current draw usually indicate shorted fields.

If above conditions exist, then the starter motor needs to be replaced.