rvg8tor
Joined: 06 Apr 2009
Posts: 50
Location: Olympia, WA
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 Posted: Tue Apr 19, 2011 12:07 pm Post subject: Single shunt with two altenators Main and Stby |
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I have a Z12 design with the SD20 standby alternator. I am trying to decide if I can leave out the shunt for the SD20. The Dynon FlightDEK 180 supports a single ammeter so here are my thoughts.
1. Run each alternator to separate ANLs but tie the down stream ends of the ANLs together then to the high side of the ammeter shunt, the low side of the shunt takes the power flow to the battery side of the start contactor. My start contactor is on the firewall side but the battery contactor is on the cockpit side, I use the fat wire that ties the battery contactor to the start contactor for double duty, it gets power to the starter via the start contactor but when not starting is carries the power from the alternator though the firewall, the main buss power picks up at the switched side of the battery contactor.
With this setup the standby alternator only comes on when the bus voltage drops, which means the main alternator has or is failing, so since only one alternator at time is working this will allow the shunt to work double duty as it were, it shows the current going to the bus and battery, this current supplied is either from the main alternator or the standby one.
So will this work or am I missing something important here.
Option 2:
Just don't have a shunt for the standby alternator and use the single shunt for the monitoring of the load on the main alternator.
I know I can install a second shunt and use a switch to send the signal to the EMS for which shunt data I want displayed but this seems like extra parts for little benefit.
As you can tell I really don't want to install a second shunt if I can help it. I also don't plan to use the hall effect option for the standby regulator.
Thanks for any help.
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_________________
Mike "Nemo" Elliott
RV-8A QB (Engine)
www.mykitlog.com/rvg8tor |
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