Charging & starting

Pico Technology

Charging Circuits

Alternator voltage and current – 12V - 24V

The purpose of this test is to assess the controlled output of the alternator in relation to electrical load on the battery.

How to perform the test

View connection guidance notes.

1. Connect PicoScope Channel A to
the vehicle battery terminals.

2. Connect the high amp clamp to
PicoScope Channel B.

3. Switch on and zero the high
amp clamp before connecting to
the battery positive cable.

4. Start the engine and run at idle.

5. Minimize the help page. You will see that PicoScope has displayed an example waveform and is preset to capture your waveform.

6. Start the scope to see live data.

7. Switch on electrical auxiliaries (headlights, heaters, etc.) and vary engine RPM whilst observing your waveforms.

8. With your live waveforms on screen stop the scope.

9. Turn off the engine.

10. Use the Waveform Buffer, Zoom and Measurements tools to examine your waveform.

Note

The orientation of the clamp relative to the wire will determine whether it has a positive or negative output. If a live waveform does not appear on your screen, or appears to be inverted, try reversing the orientation of the clamp.

Alternator AC ripple – without ECM control

The purpose of this test is to check the rectification of the alternator output voltage, where the alternator output is not regulated by the Engine Control Module (ECM).

How to perform the test

View connection guidance notes.

1. Connect PicoScope Channel A to the alternator B+ terminal.

2. Minimize the help page. You will see that PicoScope has displayed an example waveform and is preset to capture your waveform.

3. Start the engine and allow it to idle.

4. Start the scope to see live data.

5. Switch on electrical consumers and increase engine RPM whilst observing your waveform.

6. With your waveform on screen stop the scope.

7. Turn off the engine.

8. Use the Waveform Buffer, Zoom and Measurements tools to examine your waveform.

Alternator - smart charge (Ford)

The purpose of this test is to check the command, feedback, and output voltage signals from a Ford-type smart charging alternator.

How to perform the test

View connection guidance notes.

1. Use manufacturer’s data to identify the alternator command, feedback, and output circuits.

2. Connect the high amp clamp into PicoScope Channel A, select the 200 A range and zero the clamp.

3. Connect the high amp clamp around the alternator B+ cable.

4. Connect PicoScope Channel B to the alternator feedback circuit.

5. Connect PicoScope Channel C to the alternator command circuit.

6. Start the engine and allow it to idle.

7. Minimize the help page. You will see that PicoScope has displayed an example waveform and is preset to capture your waveform.

8. Start the scope to see live data.

9. Switch on electrical consumers and vary engine RPM whilst observing your waveforms.

10. With your waveforms on screen stop the scope.

11. Stop the engine.

12. Use the Waveform Buffer, Zoom and Measurements tools to examine your waveform.

Parasitic drain test – battery

The purpose of this test is to evaluate the level of parasitic current draw from the battery during a vehicle's shutdown phase and sleep periods.

How to perform the test

View connection guidance notes.

1. Connect PicoScope Channel A. across the battery terminals.

2. Connect the low amp clamp to PicoScope Channel B select the 20 A scale and zero the clamp.

3. Wait around 10 minutes for the current clamp to acclimatise to test conditions (temperature), then connect around the battery earth lead.

4. Minimize the help page. You will see that PicoScope has displayed an example waveform and is preset to capture your waveform.

5. Start the scope to see live data.

6. Some vehicles may take around 45 minutes to completely close down all electrical systems. (You may need to test for longer periods, e.g. Over-night to acquire sufficient test data).

7. With your waveforms on screen stop the scope.

8. Apply a Lowpass Filter to clean the Channel B waveform.

9. Use the Waveform Buffer, Zoom and Measurements tools to examine your waveform.

Note

Ensure the test equipment is able to function for an extended time period e.g. current clamp battery condition, scope and pc power supply.

The vehicle must achieve full electrical shut down, with all openings to register as closed with the Body Control Module (BCM), the alarm activated, the emote keys out of range and aftermarket accessories set as per the customer's usual use.

Alternator AC ripple - with ECM control

The purpose of this test is to view the rectification of the alternator output voltage, where the alternator output is regulated by the Engine Control Module (ECM).

How to perform the test

View connection guidance notes.

1. Connect PicoScope Channel A. across the battery terminals.

2. Connect the low amp clamp to PicoScope Channel B select the 20 A scale and zero the clamp.

3. Wait around 10 minutes for the current clamp to acclimatise to test conditions (temperature), then connect around the battery earth lead.

4. Minimize the help page. You will see that PicoScope has displayed an example waveform and is preset to capture your waveform.

5. Start the scope to see live data.

6. Some vehicles may take around 45 minutes to completely close down all electrical systems. (You may need to test for longer periods, e.g. Over-night to acquire sufficient test data).

7. With your waveforms on screen stop the scope.

8. Apply a Lowpass Filter to clean the Channel B waveform.

9. Use the Waveform Buffer, Zoom and Measurements tools to examine your waveform.

Relative compression - gasoline

The purpose of this test is to compare engine cylinder condition by observing the electrical current drawn by the starter motor during engine cranking.

How to perform the test

View connection guidance notes.

1. Disable the vehicle’s fuel injection.

2. Connect the high amp clamp to PicoScope Channel A.

3. Select the highest range and zero the clamp.

4. Connect the clamp to either the positive or negative battery lead.

5. Minimize the help page. You will see that PicoScope has displayed an example waveform and is preset to capture your waveform.

6. Start the scope.

7. Crank the engine for around 5 s to capture your waveform.

8. Use the Waveform Buffer, Zoom and Measurements tools to examine your waveform..

Note

If your engine has a cable operated intake throttle, depress and hold the accelerator pedal during cranking to maximise the air volume drawn in to the engine.

The orientation of the clamp relative to the wire will determine whether it has a positive or negative output. If a waveform does not appear on your screen, or appears to be inverted, try reversing the orientation of the clamp.

Relative compression - diesel

The purpose of this test is to compare engine cylinder condition by observing the electrical current drawn by the starter motor during engine cranking.