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Thread: Battery disconnect switch

  1. #1
    Senior Member ken nougaret's Avatar
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    Default Battery disconnect switch

    I want to have a way of safeguarding someone turning on my master switch and draining my battery or pushing the start button causing the prop to spin. At first i was thinking of a hidden switch in line with the master. But now im thinking might be better is a battery cutoff switch like i have on my boat.
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  2. #2
    Senior Member ken nougaret's Avatar
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    Default Re: Battery disconnect switch

    Was wondering if anyone else did something similar to this cutoff switch?
    Thanks, Ken

  3. #3
    Senior Member Dave S's Avatar
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    Default Re: Battery disconnect switch

    Ken,

    I can see the safety question that might come up if the plane has a push button in addittion to potential issues with plain old battery drain.

    Our case is a little different with our S7 since we use the keyed ingntion/start switch so it doesn't have a push button.

    Since we decided to have door locks for travel, etc, also use them in the hangar to keep the earthlings out if one happens to get inside the hangar. Admittedly door locks have less than complete value as a theft deterrent as someone with a backhoe can probably tear the door of the hangar and haul the plane out if they are really intent on being a toad, but the door locks keep a lot of dumb stuff and low level stuff from happening.

    After many years of rental/club deals before we got our Kitfox, it always seemed the biggest risk of battery drain was the operators leaving a master on. Simple as a kitfox is, I always use a concise checklist for shutdown - so far I haven't embarrassed myself (that way)

    Fly Well,
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  4. #4
    Senior Member Norm's Avatar
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    Default Re: Battery disconnect switch

    I put one in my Model IV that I am rebuilding mostly for battery drain. Also as a safty cutoff in case of emergency. And of course it now makes a checklist mandatory.
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  5. #5
    Senior Member jrevens's Avatar
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    Default Re: Battery disconnect switch

    FWIW, I decided to use a small momentary contact key switch for start, like Vans does it with the RV-12, along with a pair of toggle switches for ignition. That gives me the security feature for the start function. A battery disconnect switch adds several more connections/potential failure points to the circuit (switch contacts & wire connections). Battery drain should be a non-issue - if you can remember to turn off the main disconnect you should be able to remember to turn off the master switch, and some stranger turning on switches on your panel is EXTREMELY rare in my experience of 26 years with my other homebuilt, in which I've been all over the country, to gobs of fly-ins (19 times of staying all week in OSH for instance). That airplane has a sliding canopy, & most days when at a fly-in it sits on the ground with the canopy completely open. It's very easy to reach in & touch everything on the panel. It's a little harder & more obvious to actually open a door & touch things. I debated in my mind about door locks on my Kitfox... I do have a canopy lock on my Thorp. Here's the thing - locks keep the "honest" thieves out. If a determined thief wants your radios, or headsets, or whatever bad enough, it will likely be worse for you if they break in, creating who knows what kind of damage. I have a friend who's locked airplane was severly damaged when a thief broke the canopy to steal his radios. He wished he had never locked it.
    John Evens
    Arvada, CO
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  6. #6
    Administrator DesertFox4's Avatar
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    Default Re: Battery disconnect switch

    I've seen and flown several Kitfox that had a starter button disconnect switch hidden under the panel. Sometimes referred to as "Air Show Switches". Simple installation of a switch in the wire that goes from the starter button to the starter solenoid. Put it anywhere you like and of course don't label it.

    This helps nothing with leaving the master switch on though.

    For that infrequent but frustrating scenario I started carrying one of these.
    $69.99 on Amazon and free shipping.
    IMG_7554.jpg
    It has two USB ports that
    I use mostly to extend the battery life on my iPad Air 2 and my Stratus S2 for all day flying in my model 4 but it will easily jump start my Rotax if need be.
    Total kit weighs 2 pounds and packs 300 cranking amps. I carry one in each of my vehicles.


    DesertFox4
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    912 ULS Tri-gear


  7. #7
    Senior Member HighWing's Avatar
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    Default Re: Battery disconnect switch

    Good discussion. I think a lot has to do with our specific environment. My hangar is ten feet off from my left shoulder as I type this. If my airplane was in a shared hangar or outside for any period of time, the battery cut off switch might just save some grief. My problem seems to be the low charge battery issue due to the master switch being left on. My start switch is a keyed switch, but I have never removed the key from the switch and that with similar experience over a similar period of time as John. I don't have ready access to the battery and it would require cowl removal to put a battery cut off switch. For me, I guess, the solution would be strict adherence to a checklist protocol. It makes me think of Paul's comment when flying amphibious floats - verbalize the check list EVERY TIME.

    Regarding door locks. I do have them on my second IV but only on the pilot side. The passenger door has no external handle on the closing latch. The first IV had a cable that went under the belly between handles on the two twist locks that I could fasten when desired. My new IV has the typical allen wrench activated lock with a twist. Without my special wrench (key), the thing just spins without engaging the latch.

    I also have one of the battery back up boosters like the one Steve linked to. Then again, I have no idea how I would use it in the event I needed to given where my battery is.
    Lowell Fitt
    Goodyear, AZ


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  8. #8
    Super Moderator Av8r3400's Avatar
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    Default Re: Battery disconnect switch

    I used a keyed off on switch on the panel for my master switch. Easy and simple.
    Av8r3400
    Kitfox Model IV
    The Mangy Fox
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  9. #9
    Senior Member ken nougaret's Avatar
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    Default Re: Battery disconnect switch

    Thanks you Steve for helping me get logged back in. Now i can see which battery booster you have.
    I think im going with something like Norm has for my battery disconnect.

  10. #10
    Administrator DesertFox4's Avatar
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    Default Re: Battery disconnect switch

    Happy to help Ken.


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