I am new to the forum so please dont be too harsh on me!
I am a jet jockey although i want to brush up on single engine pistons and i decided to tackle the system that used to scare me the most: the dreadful electrical system!
My questions, are related to the 172 sp model without garmin 1000 and are the following:
Looking at the schematic i can see, or should i say guess, that power from the battery is fed through the external power contactor to the battery contactor, featuring a number of terminals: one connected to the battery and supplying battery power to the hot wired item - the clock - at all times and to the contactor itself whenever theBATT side of the switch is set to ON, one to the starter and to the SENSE port of the ACU which i completely ignore what it is - not the ACU but the SENSE port! The other thing around the contactor with what i guess a diode i have no idea either!
Second question: power from the alternator is fed to the ACU which modulates the excitment charge to the axial rotor controlling the magnitude of the electromagnetic field and thus the current output. From the ACU i guess through the ALT INPUT terminal on the ACU itself goes to the ALT relay and from there to the bus network, am i right?
Third question: the ALT relay has several terminals: one from the starter and i guess controllng the power from the battery to the relay coil whenever e ALT side of the switch is set to ON, in this case the solenoid is energized and battery power is fed to the ACU power in port flashing the alternator field and bringing it online. Now is power from the alternator fed through the alternator relay and the starter relay and the battery relay back to the battery? And how is it distributed to the bus network?
So far, many thanks for your willingness and if there is anything you would like to know about the chally, i would be more than glad to assist!