Wiring a "dead drain" battery electrical system

Discussion in 'Instruments / Avionics / Electrical System' started by cluttonfred, May 10, 2016.

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  1. May 10, 2016 #1

    cluttonfred

    cluttonfred

    cluttonfred

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    Eliminating the engine-driven aspect of an electrical system simplifies it greatly, but there are still a few things to consider. I'd love to hear from folks with more knowledge and experience on these notions and questions:


    1. What about using a mechanical battery disconnect switch as the "master" either within reach if the battery is located within reach? If key-operated it could be used to secure the system when not in use.
    2. Or, if the battery is farther away, how about one with operated by a push/pull rod or cable?
    3. Should there be a fuse or circuit-breaker right at the battery in case of a catastrophic short-circuit?
    4. Any strong opinions on integrated switches-circuit breakers vs. separate switches and breakers vs. separate switches and fuses?
    5. There are likely to be a few other items powered by the battery (12v gauges, maybe a radio or an anti-collision light), any special do and don't considerations when wiring those?
    6. In some designs including the VP-1 and VP-2 the fuel is very close at hand. Any special considerations for reducing fire danger with this kind of setup?

    Cheers,

    Matthew
     
  2. May 10, 2016 #2

    BJC

    BJC

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    My airplane has a battery behind the seat, with a mechanical disconnect switch mounted about 8 inches from the battery. It powers a light weight starter and a hand held radio. Works just fine. Remember to bring out a lead for the battery maintainer.


    BJC
     
  3. May 10, 2016 #3

    cluttonfred

    cluttonfred

    cluttonfred

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    Thanks, BJC. Can you reach the disconnect in flight? And do you have any circuit breakers, fuses or switches in the system? Sounds like you have magneto ignition, where I was thinking of a battery-powered distributor or EI.
     
  4. May 10, 2016 #4

    Turd Ferguson

    Turd Ferguson

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    A total loss ignition is one thing......total loss electrical system I can't imagine. I'd want neither one on a flying machine. Oops, unrelated to threat, disregard.

    Seriously, I can't imagine a reason to disconnect the battery in flight. That would kill the engine, compounding any previous abnormal/emergency.
     
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  5. May 10, 2016 #5

    cluttonfred

    cluttonfred

    cluttonfred

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    The logic was that, if running a total loss/dead drain ignition, you may as well make the battery a little bigger and run a couple of gauges, an LED beacon and the radio. Presumably the only reason to shut off the battery in flight would be in the case of a fire or an impending crash such as an engine out away from a field, when you would shut of the fuel and power to reduce fire risk.
     
  6. May 10, 2016 #6

    TFF

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  7. May 10, 2016 #7

    BJC

    BJC

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    Switch can be reached in flight with right hand behind the right side of the seat back.

    No breakers. One PB starter switch.

    Yes, two magnetos.

    Photo looking aft in fuselage with the seat back removed:

    Pitts Battery Switch.jpg


    BJC

    PS Anyone know how to stop the Uploader from rotating iPhone photos?
     
  8. May 10, 2016 #8

    cluttonfred

    cluttonfred

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  9. May 10, 2016 #9

    BJC

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  10. May 10, 2016 #10

    TFF

    TFF

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    It's a volks plane. No one is going to steal it.
     
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  11. May 10, 2016 #11

    cluttonfred

    cluttonfred

    cluttonfred

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    I am wounded, sir! Not all VPs are ugly, though they are generally, ummm, "rustic." ;-)

    01.jpg 35722d1413470722-enclosing-evans-volksplane-vp-2-1088782f.jpg 58042.jpg
     
  12. May 10, 2016 #12

    Turd Ferguson

    Turd Ferguson

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    that's the one I have on my camper.
     
  13. May 10, 2016 #13

    TFF

    TFF

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    I did not say I did not like them, but if Im going to steal it will have Lear or Pitts stenciled on the tail or something worth going to jail for. Not going to jail for a VP.
     
  14. May 10, 2016 #14

    cluttonfred

    cluttonfred

    cluttonfred

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    As TF pointed out, if it's powering the ignition and it falls out, you'll know it, as I believe that it is only removable in the off position. ;-)
     
  15. May 10, 2016 #15

    Daleandee

    Daleandee

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    It's a tough crowd around here sometimes ...

    http://www.homebuiltairplanes.com/f...anes-april-issue-thatcher-cx5.html#post312035

    BTW ... if looking for a dependable cutoff switch I'd consider a blade type:

    https://www.google.com/search?q=bla...48_MAhUBxSYKHToeA_oQ_AUIBygB&biw=1366&bih=643

    Wire it to the negative side of the battery.

    Dale Williams
    N319WF @ 6J2
    Myunn - "daughter of Cleanex"
    120 HP - 3.0 Corvair
    Tail Wheel - Center Stick
    Signature Finish 2200 Paint Job
    119.6 hours / Status - Flying
     
  16. May 10, 2016 #16

    Toobuilder

    Toobuilder

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    The master switch on my Mooney and Tri Pacer were simply toggle switches. In the case of the Mooney, it was mounted ahead of the firewall and actuated by a push/pull cable
     
  17. May 11, 2016 #17

    goldrush

    goldrush

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    I you use a relay instead of a mechanical system, ensure that it is rated for continuous use and rated for maximum current. The operating coil in any other type can overheat.
    You may find this list of measured starter cranking currents etc from the aerolithium site, useful..

    PISTON Battery needed
    A good way to know what cranking amps your starter needs to start engine; use a clamp-on ammeter around a battery cable.

    HKS 700E - 60Hpwr - 125amps ....... 220A

    Rotax 582 - 65 Hp - 137A .................220A

    Rotax 503 - 52 Hp - 153A ...................220A

    Hirth 2704 - 55 Hp - 167A ..................220A

    Cont. O-190 - 75Hp - 175A ..............330A

    Lyc. I O - 360-200HP - 350A ............440A
    Lyc. I O 540, Cont. 470 / 550 ..........440A
    Cont. 550 - 24V .................................330A
    V W engine .........................................330A

    TURBINE
    Solar T-62t - 32 ..................................550A
    std T-62t ..............................................440A

    I have recently used a "$10 cheapie" "charge changeover" such as this from Malaysia on my rotax 503 SSDR (similar to Part 103) machine.

    12V 200A Relay 4 Pin Car Auto Heavy Duty Install Style Split Chargeover | eBay
     
  18. Jun 28, 2016 #18
    Hi everyone...i am new here. I worked on some projects and as per my experience if running a total loss/dead drain ignition, you may as well make the battery a little bigger and run a couple of gauges, an LED beacon and the radio. Presumably the only reason to shut off the battery in flight would be in the case of a fire or an impending crash such as an engine out away from a field, when you would shut of the fuel and power to reduce fire risk.
     

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