Voltage Drop Test
Using a DVOM (Digital Volt Ohm Meters) you can test for continuity as well as voltage. If you check a connection for continuity, it can show good as it does have a connection but it can still be bad as the connection is no good for voltage. To clarify, there are hundreds of strands of wires within a battery cable. If most of the strands are bad or corroded, it will show a good continuity connection but the strands will not be able to send good voltage from the battery to the starter or starter solenoid… It would be fine for a light electrical load, but not a heavy amperage load like a starter requires. Thus,,, the starter barely turns or does not turn.
To isolate where the issue is, a Voltage Drop Test is the only truly effective means to find the answer without tearing things down.
A load will be required to do this test, in our case, that load is almost always the starter and in some case can be a starter solenoid if it is dirty and corroded on the inside.
Generally speaking, when you test across an item you WANT a 0.1 volt difference. However, 0.4 is acceptable for items such as a starter. Long cables and starter solenoids should be 0.2 or 0.3 difference.
CHECKING THE STARTER CIRCUIT
To check the starter circuit for excessive resistance, you need to measure the voltage drop at the battery, battery cable connections and starter while the engine is being cranked.
The first check is "available battery voltage." For the starter to crank at normal speed, the battery must be at least 75% charged (12.4 volts or higher). Low battery voltage can not only affect the starter but every other electrical system on the ski. Do NOT have it on a charger or being jumped at the time of this test. It will make all values incorrect.
A. Chances are it will not start already, so this step is not required. However, if it does start, then disable the engine so it will not start when it is cranked (Ground the ignition coil wire, or disable the ignition circuit or fuel pump relay.) Limit cranking time to 15 seconds or less.
B. Set your DVOM to the 20 volt scale, then connect meters positive (+) lead to battery positive (+) post (not the clamp or cable), and the meters negatives (-) lead to battery negative (-) post. Crank the engine and make a note of the displayed voltage.
C. Connect your meters positive (+) lead to the battery terminal stud on the starter, and the meters negative (-) lead to the starter housing. Yes, it is easier to start at the battery and work your way to these connections, but this will confirm if you have a voltage drop issue or not. If so, then continue with the test.
E. While cranking the engine, record the volt reading.
F. Compare the two voltage readings. If both are the same, there are no excessive voltage drops on the positive feed side.
G. If available voltage at the starter is not within one (1) volt of battery voltage, there is excessive voltage drop in the circuit.
The next test is for voltage drop on the positive side of the starter circuit.
A. Make sure the battery is fully charged.
B. Disable ignition.
C. Set DVM on 2 volt scale.
D. Connect the meters positive (+) lead to positive (+) battery post, and the meters negative (-) lead to the terminal stud on the starter (positive wire from solenoid). While cranking the engine, record the voltage reading.
The maximum allowable voltage drop including the solenoid or external relay in the starter circuit should be 0.6 volts or less.
If you find more than a 0.6 volt drop in the starter circuit, you can isolate the bad connection by using the following voltage drop tests.
* Check the positive battery post and cable connection by measuring the voltage drop between the two while cranking the engine. Connect the meters positive lead to the battery post and the meters negative lead to the cable clamp. A good post/cable connection should have zero voltage drop.
* Check the positive battery cable by measuring the voltage drop end to end (test lead on cable end, not the battery) while cranking the engine. Connect the meters positive lead to the clamp on the positive battery cable, and the meters negative lead to the end of the cable at the starter. Crank the engine and note the voltage reading. A good cable should have a voltage drop of 0.2 volts or less.
* To check the starter solenoid or relay connections, connect the meters positive lead to positive battery terminal on the solenoid or relay, and the meters negative lead to the starter motor terminal. Crank the engine and note the reading. A good connection should have a voltage drop of 0.2 volts or less. This will test the solenoid and the cable going to the starter. To test ONLY the solenoid, take the negative lead to the OUTPUT side of the solenoid. Crank the engine. The voltage drop should be 0.2 volts or less. If it is 0.3 or more, replace the solenoid as the internal contacts are dirty.
Next, you need to check the negative side of the starter circuit. To check the entire circuit, connect the meters positive lead to a clean spot on the starter motor case and the meters negative lead to the negative battery post. Crank the engine and note the reading. The voltage drop on the negative side should be 0.3 volts or less.
If the voltage drop is too high, set your DVOM to the 2 volt scale and start checking each connection on the negative side to find the bad connection or cable. Use the DVOM leads to check across each connection while cranking the engine as before.
Check the negative battery post/ground cable connection (should be zero voltage drop).
Check the negative ground cable from the battery to the engine (should be 0.2 volts or less).
Check between the negative battery post and starter housing (should be 0.3 volts or less). (I do not think any of our skis have a negative post, but if yours does, then do this test).
Check between the engine block and starter housing (should be 0.10 volts or less).
Yes, this is a lot of different steps. But if you follow them, you WILL find where your electrical issue is in regards to a voltage drop or defective item.
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