Thread Content
What is the Ford Focus smart alternator: The Ford Focus smart alternator was the first to adopt an alternator system that is electronically controlled by the engine’s ECM or Power Control Module (PCM). This system, known as “smart charging,” is now used by most automobile manufacturers. Under this system, the generator operates at full capacity only when it is absolutely necessary and the battery remains in a constant, healthy charging state. The temperature of the battery is determined by the intake air temperature sensor; when the temperature is low, the battery is capable of accepting a slightly higher charging voltage. Therefore, the ECM charges the battery with a slightly higher level of energy when the temperature is low, and adjusts the charging rate to balance it with the relative load consumption. Now that we know what a Ford Focus smart alternator is, let’s take a look at how to measure it using an oscilloscope. Connection method between the oscilloscope and the generator: Channel 1: For the generator’s current output, set the current probe to 100X, and connect the BNC connector to channel 1 of the oscilloscope. Connect the current clamp to the main battery positive cable from the generator to the battery. Turn on the current probe and adjust the zeroing settings. Channel 2: Connect a BNC-to-banana plug test cable for the generator’s feedback to channel 2 of the oscilloscope. Connect a probe to the positive terminal of the test wire, and connect a black alligator clip to the negative terminal of the test wire. Connect the black alligator clip to the engine ground point. The probe pin detects pin 1 of the multi-pin connector on the generator. Channel 3: The command signal sent to the generator is connected via a BNC-to-banana plug test cable to channel 3 of the oscilloscope. Connect a probe to the positive (colored) terminal of the test wire, and connect a black alligator clip to the negative (black) terminal of the test wire. Connect the black alligator clip to the engine ground point. The probe pin detects pin 2 of the generator’s multi-pin connector. Oscilloscope settings: If your oscilloscope is part of the Mackox ATO series designed for automotive use, you simply need to open the automotive setup package, select the charging/start-up circuit, then choose the Fox intelligent generator. By clicking OK, the oscilloscope will adjust all the settings for you. If you are using a different oscilloscope, then the following settings need to be made. First, we set the attenuation ratio of Channel 1 and the current probe to the same value of 100X, while Channel 2 and Channel 3 are set to 1X respectively. Then the probe type for channel 1 is current, while channels 2 and 3 are voltage. The vertical setting for Channel 1 is set to 20A, while Channels 2 and 3 are set to 5V respectively. Set the time base to 10ms. The second channel is monitoring from the generator; the signal is a feedback to the engine’s electronic control module (ECM), in the form of a constant square wave or pulse width modulation signal. The duty cycle of the signal changes as the generator’s output increases. Channel 3 is the command signal for the generator; this signal comes from the ECM and changes according to the load requirements. It is also a square wave or pulse width modulation signal. When there is no load, Channel 3 shows no signal, as the ECM does not detect any electrical devices being turned on, aside from the engine running normally. At full load, Channel 3 generates a signal, and the generator regulator increases the excitation current in response to it, thereby increasing the output current. Regardless of the power demand, the duty cycle of channel 3 will remain almost constant. The current probe for Channel 1 must be connected to the positive terminal of the battery, going from the generator to it; because if it is connected to the negative terminal of the battery, it may show the difference between the current generated by the generator and the current consumed by the electrical load. In this case, when an additional load is applied to the system, the current reading does not change significantly. Under no-load conditions, the charging current of the generator is approximately 14 amps. When we turn on the loads (such as window heaters, main headlights, and high-speed heating fans), the output current increases to around 70 amps. We can open the oscilloscope’s measurement options to observe them, namely the average value and amplitude of Channel 1, as well as the duty cycle of Channels 2 and 3.