[David Burke]

Wiring up an RV-9 - I cannot figure where my power is coming from to the master switch . I don't have a voltage regulator therefore I am not sure where the J2 is going to draw power from . Can anyone help with this headache?

 

[uk_figs]

Battery bus??

Not sure I am answering the correct problem but in my case the power to the master (split cessna type switch) comes from the battery bus. Reference the Z11 schematic, master switch powers the main bus.
Schematics (not completely current) are on my web page.

 

[rv9av8tr]

Master Solenoid power

The relay power for the Master solenoid (Vans wire P3) comes from within the solenoid on the hot battery side. The master switch goes to ground, which closes the solenoid, allowing battery power through.

http://www.mykitlog.com/users/workl...539rv&project=161&log_id=62404&photo_number=3

The starter solenoid internal relay (Vans wire K1) on the other hand requires power from the main buss to close the starter relay.

So the power flow is, closing the Master switch to Ground, hots up the main buss through the Master Solenoid, which in turn allows you to get power back to the Starter solenoid to close it for starting.

Hope that makes sense.

 

[Rivethead]

You see the boot in the picture below with Here written on it. That wire goes to the Master switch which then goes to ground.

 

[Steve]

J2

Ref dwg OP-10. Top center. The rear view of Vans 60 amp internally regulated alternator has one end of J2 connected to the lower left leg of the 3 terminal connector. The other end of J2 goes to the master switch as you stated.

Steve

 

[Rivethead]

Ok I was trying to be too simple in my last post. The wire marked Here basically closes the solenoid which energizes the master buss and at the same time the master solenoid puts power to the starter solenoid. The wire I have marked J2 in this next picture goes back to the switch (the alternator switch) that takes power off the master buss and energizes the field coil of the alternator. J1 is the B lead from the alternator. By comparing the two pictures you can trace how the juice flows.

There has been a thread recently that makes me think that an alternator switch isn't really needed with an internally regulated alternator. I still don't know what to think about that but perhaps just a pullable circuit breaker is all that's needed. I imagine it would be something like master on and the alternator is on with the master buss, that is until something opens the circuit breaker. Then apparently, according to that thread, the alternator would still be alternating anyway because the field coil is energized via the regulators circuitry.

 

[rv9av8tr]

Shunt measuring "I" to/from Bat?

RH,
It's a little hard to tell for sure from the picture, but is your shunt there measuring current going to/from just the battery? It would be nice to know your battery isn't supply the buss (in discharge).
Are you using another shunt to monitor current flow too your main buss from the alternator?

I'm just now putting together my electrical drawings and I'm on a steep learing curve too.

You see the boot in the picture below with Here written on it. That wire goes to the Master switch which then goes to ground.

 

[Rivethead]

It's doing the Cessna thing, it measures charge and discharge. I'm using a Dynon D10 to measure my flow. In the Dynon manual it shows a schematic that looks as if two of the wiring methods do the same thing. It just looked like they must have drawn it wrong for the longest time to me. Then I realized the that the high and low measurements were switched between the two depictions, a very simple change that makes a big difference. Also think about this. If the battery is discharging, current flow through the shunt will be traveling to the buss wire but If the alternator is charging the battery the current will be flowing toward the battery and also energizing the buss. The way it's set up it gets measured in both directions.