gammaxy wrote:Here's a shot in the dark:
- Master switch open, alternator switch closed
I believe this would correspond to Master Off, Alternator Off with the way you originally wired the alternator relay.- Master switch closed, alternator switch closed (Master on, alternator off)
Capacitor begins charging until alternator relay switches to N.O. position.- Master switch open, alternator switch closed (Master off, alternator off)
Alternator relay switches back to N.C. position. Now the capacitor has a discharge path to ground through the relay coil and alternator switch. The relay opens and closes multiple times as the capacitor discharges to the point it can no longer open the relay.
Wiring the alternator relay to the N.O. position should prevent this scenario as once the circuit opens, there will be no path for the capacitor to discharge through the coil.
If this is the case, then it wasn't the capacitor making the noise, but a strange relay sound caused by it partially actuating multiple times. I can't think of any other scenarios for the capacitor making a noise without involving a short circuit or arcing inside the capacitor, but without the regulator, starter motor, 20A fuse, this is the only explanation that comes to mind, strange as it seems.
sonex1374 wrote:Michael,
Let me offer a few suggestions.
Ammeter shunt placement: The ammeter can tell you different things depending on where it's located. You have it placed between teh power bus and battery. This will tell you how much current the power bus is drawing *out of the battery* at any given time. It won't tell you the total draw because the alternator is supplying power to the bus also, and that power doesn't go thru the shunt. Likewise, the starter doesn't go thru the shunt, so you won't see the true demand on the battery when starting. If this is what you want to monitor with the ammeter (the in-flight draw on the battery), then it's ok. If you want total draw by the power bus (from the battery and/or alternator combined), then you'll need to move the shunt. If you want total current flow into or out of the battery at any given time, you'll need to move the shunt.
Alternator Disconnect Relay: The way your diagram shows it, the alternator disconenct relay is always "closed" and the regulator output (alternator) is always tied into the power bus. In fact, once the engine is running, you could turn off the master switch (disconnecting the battery) and the regulator output would continue to keep the panel running. Activating the "Alternator Switch" would disconnect the regulator (alternator) and power would cease to flow into the power bus or battery contactor.
If you reverse the connection of the alternator relay from the "Normally Closed" terminal (what you have now) to the "Normally Open" terminal, the alternator will be disconnected (offline) until you activate the switch. The choice is yours, however, there are a few other considerations. If your regulator goes haywire, gets really hot, and tries to melt down in flight, you'll be able to keep the regulator from pumping in power to your bus by disconnecting the alternator relay, but you'll be unable to stop the regulator from continuing to melt down. This is because the alternator is *always* supplying the regulator with AC current, whether the regulator is connected to anything or not. Moving your alternator disconnect relay to the AC lines coming from the alternator (before the regulator) completely isolates the alternator from the regulator and not just the power bus. It's probably a remote chance or a regulator failure that melts itself down, but this method gives you a chance to stop it in it's tracks.
Squeeling Noise: The noise is possably due to the capacitor discharging into the system. Try disconnecting the capitor from the system and see if the noise goes away. If it does, then that's what making the squeel. One option is to place a small load across the capacitor that will slowly discharge it once the battery (or regulator) have stopped supplying power. I suggest a small resitor (1/4 watt, 10k ohm) or 12v lamp connected to the + and - leads. This will "drain" the capacitor without really affecting the rest of the system while in normal operation.
I hope this makes sense and helps.
Jeff Shultz
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