9V battery to light model rocket

Discussion in 'Rocketry Electronics and Software' started by bryce910, Dec 28, 2019.

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  1. Dec 28, 2019 #1

    bryce910

    bryce910

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    Hey everyone!

    I am new to model rockets and I was building my own launch controller, my issue is that when I hit the button to launch the rocket the igniter slowly smokes but never launches the rocket.

    is a 9V not enough for the low power rocket igniters?

    If not, what small batteries would you guys suggest using?
     
  2. Dec 28, 2019 #2

    dhbarr

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    How is your controller wired, and which 9V battery? Most people recommend 12v, but I get away with 4xAA's for mid-range composites if the batteries are good quality.

    Keep in mind the modern Estes white/clear tips don't have any pyrogen / won't burst into flame. Do you have a multimeter to measure resistance before/after you fire them?

    #1 thing I run into when helping people launch is stabbing the launch button instead of press-and-hold.
     
  3. Dec 28, 2019 #3

    Cameron Anderson

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    For Estes I use a circuit with three 9v batteries
    ...2 wired in series and a third in parallel. Works fine.
     
  4. Dec 28, 2019 #4

    DAllen

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    Most club launch systems use some sort of 12v battery for launch. My personal controller is a old Aerotech Interlock that hooks up to a car battery. My club uses rechargeable 12v gell-cells (I think that's what those batteries are called.) I'm not surprised that a single 9v might be struggling a little. You could try ematches instead which definitely work well off of 9v's. I've never used ematches though on black powder motors but I've heard of people doing that.

    -Dave
     
  5. Dec 28, 2019 #5

    prfesser

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    What gauge are your leads from panel to pad? 9V at the battery may not be 9V at the pad, due to resistance of overly-thin leads. If holding a motor starter to the battery terminals lights it, but doesn't do so in the launch system, that may be part of the problem. The old standby for modroc launch system leads is a cheap 16 ga 15 foot extension cord.

    A friend tried making a launch system with 50 ft of 20 ga or 22 ga wire. Wouldn't light nothin.
     
  6. Dec 28, 2019 #6

    g.pitts

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    It is more than voltage - it is how much power can the battery deliver to the igniter. Not all 9V batteries are the same. The internal resistance of some 9V batteries is higher than others, which means as more current is demanded by the igniter, the voltage and current at the igniter drop to a point of equilibrium with the resistance of the igniter. If you're sold on a 9V battery, your best shot is likely going to be this one. Otherwise, in a small form-factor, you might consider a Lithium Polymer battery, but it requires care in terms of charging and storage.

    Just my $0.02...
     
  7. Dec 28, 2019 #7

    hprocketeer

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    The Estes website has a very good section for education. Search for model rocket launch systems. All the electrical theory is there.

    I remember a different older publication that explained why 9v “transistor “ batteries by themselves won’t work on sonic ignitors.
    Basically it’s internal resistance is too high to source the current required.

    Read and enjoy.
    Mike
     
  8. Dec 28, 2019 #8

    Andrew_ASC

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    I’ve lit MJG FireWire 3’ directly with a 9V.

    But yeah if your making a pad control box for HPR get something with WAY more amps. I think at Min we tried 6V flashlight batteries. They kinda work okay for limited number of uses. We’re cheap lol.
    Best answer was Lipo or car battery.

    Granted that was for like 200’ of pretty thick cable with an automotive relay.
     
  9. Dec 29, 2019 #9

    neil_w

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    9V alkalines are not great for this purpose. If you must use one, make sure it is a good and fresh one. Seriously!

    Well this certainly could use some elaboration. I cannot quite imagine what circuit you could be using configured like this.
     
  10. Dec 29, 2019 #10

    Cameron Anderson

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    Simple push button ignition circuit. 18ish volts, 400mah, 2 alligator clips. I made it before I started using lipos for everything and I let the neighborhood kids use it and everyone had 9Vs laying around.
     
  11. Dec 29, 2019 #11

    Voyager1

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  12. Dec 29, 2019 #12

    kuririn

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    OP says that the igniter smokes but rocket doesn't launch. The new Estes starters no longer have a pyrogen tip, so the hot wire must be in contact with the propellant.
    If the igniter smokes then the wire is getting hot, so perhaps it's not contacting the grain?
    Just a thought.
     
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  13. Dec 30, 2019 #13

    scadaman29325

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    Before I learned you had to push two buttons on the controller, I used a 9v transistor battery straight wired to launch our rockets. DID NOT WORK ON A 3 ENGINE CLUSTER, but everything else worked great.
     
  14. Dec 31, 2019 #14

    bryce910

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    Hey guys!

    After playing around, I was able to get it working with running two 9V batteries. However, with that being said, I have moved over to the electronic matches that someone mentioned above. I was able to easily ignite the low power rockets via that.


    Thanks everyone for your help!

    :)
     

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