B & C spline-driven exp. alternator

Discussion in 'Firewall Forward / Props / Fuel system' started by BJC, Apr 11, 2019.

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  1. Apr 11, 2019 #1

    BJC

    BJC

    BJC

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  2. Apr 11, 2019 #2

    Toobuilder

    Toobuilder

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    I have a little 20 amp backup unit on the RV-8. Never been used in anger, but it always works when I do the ops check. Other than that, not much to report.

    That said, there are some on VAF who are running them as primary alternators in an attempt to shed the weight and complexity of the belt driven unit. Have not heard anything but positives. A search over there will bring up more info.
     
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  3. Apr 11, 2019 #3

    Victor Bravo

    Victor Bravo

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    Bill Bainbridge (the B in B and C) is absolutely first class. I had the privilege of having my booth next to his at Oshkosh one year, and I watched for a whole week how he deals with customers, and I heard what he said before and after customers came to visit his booth. I will definitely be happy to do business with him, and I believe he is a very highly qualified person to give you real-world answers. Sorry I have no experience or knowledge about the specific product, application, etc.
     
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  4. Apr 12, 2019 #4

    Lucrum

    Lucrum

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    I own a B&C 28v spline driven alternator. It's mounted on an accessory drive pad of my GE T-58-8B. I had an adapter spline 3D printed using a material similar to what the alternator spline is made of. And I also had to fabricate an adapter plate. I have not however run the engine yet.
     
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  5. Apr 13, 2019 #5

    bifft

    bifft

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    Have the SD-8 8-amp one in my RV. Also have thier "crowbar" overvoltage module. Was easy to install, has given me zero problems (once I had the overvoltage wired correctly).
     
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  6. Apr 13, 2019 #6

    HomeBuilt101

    HomeBuilt101

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    >What are the pros and cons for the spline-driven verses the belt driven?

    Finally I get a chance to give back to the community and assist someone!!!

    I have a SD-20 (spline driven B&C 20 amp) on a Lycoming IO-540 and I am very happy with it. I have two independent electrical buses and the SD-20 powers the smaller bus while the SD-60 (belt driven B&C 60 amp) powers the big bus through the multi-color magic of EFIS I always see the two electrical systems operating side by side on the Dynon.

    The SD-60 has the benefit of being belt driven so the large flywheel pulley spins around and then the mechanical advantage spins the SD-60 pulley really fast even at idle so the SD-60 can produce its full rated power at low engine RPM.

    The SD-20 does not have the mechanical advantage of the belt drive so at idle it has limited production.

    On a real world example:

    The post start idle (1000 RPM) the SD-20 is only producing 12.1 volts on a 8 amp load whereas the SD-60 is producing 14.2 volts on a 23 amp load. Both sides have a battery that was bus tied during the start then isolated for all other operations so each alternator is recharging its respective battery and powering its respective bus (the SD-20 has a small electrical system and the SD-60 has a much bigger electrical system).

    Then during the engine run up at 1700 RPM run up the SD-20 is spinning fast enough to now produce 13.7 volts on a 8 amp load and the SD-60 is producing 14.3 volts on a 18 amp load.

    Later during cruise flight the SD-20 is now producing 14.0 volts on a 6 amp load whereas the SD-60 is at 14.4 volts on an 18 amp load.

    SO the SD-20 is not spinning very fast at idle so it just matters what you want to use it for...a small electrical system it would be fine.

    The customer support of B&C is OUTSTANDING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
     
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  7. Apr 13, 2019 #7

    wsimpso1

    wsimpso1

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    So, how many hours do you have on the system? Sounds like Bob Nuckoll's Z-14 dual alternator/dual battery/crossfeed design. True?

    Billski
     
  8. Apr 13, 2019 #8

    HomeBuilt101

    HomeBuilt101

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    Just built the system and only have a few hours of flight time on it. It is essentially to electrical systems with a bus tie. The left system powers the left side screen, taxi light, one radio, and the other system powers all of the same stuff listed above plus everything else on the airplane
     
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  9. Apr 13, 2019 #9

    BJC

    BJC

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    Thanks HB01. That is helpful.


    BJC
     

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