![]() |
B&C Alternator + Backup
I went to watch a buddy of mine fire up his RV-10 for the first time and noticed that he didn't have a second field switch for his B&C backup alternator .. instead, there was a "hall sensor" in place to automatically switch to the backup.
I may swap my PP for this B&C+Backup alternator setup, any feedback on this type of install? Can the regulators be installed on the hot side of the firewall? Thanks for any advice :) |
Quote:
Installation instructions state that regulators (one for each alternator) must be installed on the cold side of the firewall. The set voltage for the backup alternator is purposely adjusted lower (13 volts instead of 14-ish). The backup alternator coasts until the buss voltage reaches the lower value. With the Hall sensor you get a fancy light warning light that glows steady once the backup alternator turns on, and starts blinking if the current draw is greater than what the backup alternator can put out. The sensor does not however turn on the backup regulator. I've had mine come on once, when the B lead terminal on my primary alternator cable broke at the alternator due to a certain- ahem- error. Beings as my RV-7 has dual electronic ignitions, I was suddenly glad to have it. |
Quote:
I've built some regulators for RC so this might be an ignorant question as I'm sure the aviation regulators are far more advanced, but if the voltage goes low on the primary alternator, and the backup is enabled by the hall sensor, why would you need a separate regulator just for the backup? |
https://bandc.com/product/standby-al...kit-homebuilt/
"If the primary alternator fails in flight, the SB1B-14 controller will sense the drop in system voltage and automatically activate the standby alternator." I have this setup in my -14.BC460-H primary and BC410-H stby with LR3D-14 (primary) and SB1B-14 (stby) controllers. The controller/regulators should be mounted on the cool side of the firewall. I have a single ALT field switch on the panel for the primary alternator, but have dedicated circuit breakers for both. -Rick |
Quote:
B&C's architecture for this requires two regulators, one for each. Again, the set voltage on the backup regulator is set lower than the primary, so the backup doesn't come on until the buss voltage drops to the backup regulator's set level. The Hall sensor does not turn on the backup. Its purpose is only for the (optional) warning light logic. |
The operation is just as described above.
However, the B&C alternators are so reliable that the backup alternator may never become in use unless "- ahem- error" :) But in case if it happened, it is nice to have a backup that is just as reliable. |
Quote:
|
Quote:
Letting the b/u alternator deliver full power and supplement via the main alternator would create less parasitic HP loss from your engine, as the HP required for the b/u is static and variable for the main. Larry |
Quote:
Everything remains in this state unless the primary alt fails for whatever reason. At that point bus voltage begins to drop to what the battery can provide. When it falls below the set point of the standby regulator, it dutifully wakes up the standby alt. This is the architecture I'm planning for my -8. I really like that there's no action required by the pilot to activate the standby in case of a failure. Fewer manual tasks to execute means fewer things to potentially screw up. |
Quote:
|
| All times are GMT -6. The time now is 04:55 AM. |