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914 AMP Calculations

in 912 / 914 Technical Questions 7 years ago
This may be answered somewhere on the forum, but I'm having a hard time tracking it down. I have a 2017 AutoGyro Cavalon with 914UL. I'm trying to work out the AMP draw calculations. I have the AMP draw for the instruments, etc, but I'm not having much luck with the Rotax components like TCU / ECU, fuel pumps, etc. Can someone point me in the right direction for a spec sheet? I'd really appreciate it!

  • Re: 914 AMP Calculations

    by » 7 years ago

    Actually, I found it in section 19.5 of the 914 Installation Manual. It states 3amp per fuel pump, although it states ~1.7A for 1 and ~1.5A each for in series pumps (section 19.4.7). Is 3A the startup draw and 1.7A the running draw?
      
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  • Re: 914 AMP Calculations

    by » 7 years ago

    Section 19.5 Page 126. Total = ~8 amps.

    The Generator is 22 Amps Peak (Momentarily) and ~16 Amps Continuous (250W.) It is on a 25 Amps fuse. Don't push your luck!

    That leaves ~8 Amps for all the other consumers.
    I wouldn't go over ~ 6 amps continuous, 8 amps short term or >10 amps momentarily.
    Remember you need to leave some capacity for re-charging the battery.

    If you are trying to run a SearchLight, the External Alternator will add another 40 Amps (600W) to the mix.

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

      
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  • Re: 914 AMP Calculations

    by » 7 years ago

    Good tips Bill, thanks
      
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  • Re: 914 AMP Calculations

    by » 7 years ago

    This made me remember the "Wings of the Wind: The First World Tour in a Motorglider"
    Gerard Moss had a 912S powered motorglider equipped with cameras on the tail, wings and in the cockpit. He also had multiple laptops (or PC's? can't remember) atmospheric "sniffers" and a satellite uplink for continuous data transmission.
    All powered by the 16A generator. This was 2001 so the equipment was not very efficient.
    He had no issues!
      
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  • Re: 914 AMP Calculations

    by » 7 years ago

    Jason,

    In re-reading the thread I see you are flying a Cavalon.
    On of the Major consumers in the rear is the Radiator Fan.
    It uses 8 amps all by itself. Fortunately, it is an intermittent consumer.

    You should be able to power anything reasonable that you wish.
    You just may not be able to power ALL of it continuously.

    Fans, Transmitters, Landing Light, etc. are Intermittent consumers.
    Most devices are spec'd at Peak. Normal Consumption may be considerably lower.

    The fuel pumps claim 6 amps of the budget, but one pump at cruise will typically be drawing less than 2A.
    The Warning Lamps only draw when Lit and If they are LEDs you will lucky to see 50mA instead of the 500mA they have in the budget.
    The servo is also an intermittent device. It will only draw it's 1 amp during throttle changes.

    So while you should be prepared for the 8amps. You will typically see ~2A.
    That gives you 14 amps to play with in typical usage. Play nicely!

    Figuring a Power Budget is not as cut and dry as you would hope.
    The budget is anywhere from 0 to 14 amps depending on how you figure it!
    As has been said, hook up everything within reason and see how it works out.
    You most likely will not have a problem.

    Now, let's try and figure out how to get a 100 Million Candle Power NightSun Floodlight wired in. 60 Amps at 28 Volts might be a problem. ;)
    But it would look great on that Cavalon Gyro!

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

      
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