Adding B&C stby ALT

[woxofswa]

After my PlanePower ALternator failed on the way to OSH (bearing seizure fortunately covered under warranty by PP), I have decided to add a B&C standby ALT to my system.
One feature of that package is an indicator light for when the primary fails and the standby takes over.  What I wanted to inquire from the Dynomaster brain trust is if anyone has done the same only using a SkyView widget instead of the indicator light.
The only EMS pin I have available would be pin 2.
Comments or suggestions appreciated in advance.

 

[KRviator]

Shouldn't be too hard...

Connect the standby alternator 'active' light to Pin2 of your EMS harness.
Create a new sensor widget and map it to C37_P2.
Set it as a 'contact', and have the sensor range 0-5V as black, above 5V whatever colour you want to see when your standby is powering the bus.

 

[airguy]

You can do it, certainly...

I chose not to - because I want to have a "hard alert" on the failure of the primary, with Skyview giving me both a low voltage and high discharge amps alert that is guaranteed to get my attention. Then I will manually diagnose and bring the standby alternator online. If the standby alternator comes online automatically, without the hard alert, and it happens at a time of high workload then it's entirely possible to miss the fact that your primary alternator has taken a nap.

 

[woxofswa]

Thanks for the comments. I originally thought the same about manually selecting the transfer but B&C were quite emphatic that their recommendation was to always have both alt switches on and to let their control box do the transfer immediately and automatically.
As I’ve thought about it, it makes sense. In addition to the idiot light telling you either with its own bulb or an EFIS display that the system is running on the secondary, you also have the fact that the standby is regulated to produce about a volt less than the primary which could also be set up as an alert on your voltmeter. Red below 12.5, yellow between 12.5 and 13.9 and green above 14.0, where yellow on the voltmeter tells you that you’re on the standby, along with the idiot light and the ammeter showing an absence of battery draw if so configured.
Distraction is distraction, and it could be myriad things. Better IMO that if distracted or momentarily confused, that the system be operating and keeping the “lights on” (so to speak), and the battery charged. The positives of autoswitch seem to me to outweigh the negatives. Plus you still have other sources of information available to tell you what is happening in your airplane.
An aircraft crashed at my home airport recently killing two because, it is believed, the pilot neglected to turn on his alternators (He had two available) and got confused at the impending signs of doom.

 

[BMW_X6M]

I have the PlanePower primary belt driven as well as their backup alternator mounted on the vacuum pad. It works very well with a minimum of extra wiring. To add the backup alternator I simply ran a new field wire from a circuit breaker, and took the output on a 10 gauge wire down to where the primary alternator feeds the current meter shunt. I like how the primary runs at 14.4 volts and if I turn off its field, the backup comes online with its lower voltage of 13.6 volts. I have a LED that comes on if the primary fails driven by a wire from the primary. I can tell by the voltage which one is online and charging the system. The 30 amps of the backup is plenty of power to run the dual Dynon EFIS and everything else on the aircraft.

 

[Ronsim]

I installed the B&C S/B on my RV-6A, and chose to use the status light provided with the unit. My alert comes through the Dynon EMS 120, linked to my AFS 5600T.

I leave my S/B Alt "off" until an issue develops with the primary. I do run a test, periodically, by shutting off the primary.

Since I run "one or the other", I have both of my primary/S/B "B" leads through the same Hall Effect sensor that feeds my EMS for amperage.

Everything works really well.

Ron

 

[airguy]

I installed the B&C S/B on my RV-6A, and chose to use the status light provided with the unit.  My alert comes through the Dynon EMS 120, linked to my AFS 5600T.

I leave my S/B Alt "off" until an issue develops with the primary.  I do run a test, periodically, by shutting off the primary.

Since I run "one or the other", I have both of my primary/S/B "B" leads through the same Hall Effect sensor that feeds my EMS for amperage.

Everything works really well.

Ron

Using the same shunt is fine - but you should have separate ANL-type (or equivalent) fuses on each B-lead prior to joining them at the shunt so that a single shorted alternator does not take them both out.

 

[Ronsim]

Airguy, I appreciate the input. --- I have both B-leads going through the Hall Effect, each then goes through its own circuit breaker, before joining at the main buss. Each Alternator has a separate field breaker and switch.

 

[airguy]

Airguy, I appreciate the input. --- I have both B-leads going through the Hall Effect, each then goes through its own circuit breaker, before joining at the main buss.  Each Alternator has a separate field breaker and switch.

So you've got two alternators, with their output B-leads joining together at the shunt, and then a main B-lead breaker AFTER the shunt? That won't protect you. If one of the alternators shorts out, battery current will surge backward and trip the breaker(s) on both of them, because they are both combined at the shunt. You want your circuit breaker or fuse between the alternators and the shunt, so that if one of the alternators shorts and blows its fuse, the other is still connected.

 

[Ronsim]

Airguy, I appreciate your concern -- maybe I can clarify my arrangement. The Hall Effect amperage sensor is not a shunt, just an open donut that the B leads pass through, and the B leads are not joined at the main buss until they go through individual circuit breakers.

 

[airguy]

Airguy, I appreciate your concern -- maybe I can clarify my arrangement.  The Hall Effect amperage sensor is not a shunt, just an open donut that the B leads pass through, and the B leads are not joined at the main buss until they go through individual circuit breakers. 

Ahhh, yes, I misunderstood. That should do the trick.