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Power spike to prop when engine started? — Parallax Forums

Power spike to prop when engine started?

mosquito56mosquito56 Posts: 387
edited 2009-04-05 13:14 in Propeller 1
·Will it damage the prop system to have it on when an engine is started? The power suppy is the engines battery. Assumes the battery is in good condition. Obvious a bad battery droping below 5 volts will reset the system.

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Comments

  • PhilldapillPhilldapill Posts: 1,283
    edited 2009-04-05 05:35
    Add some bypass capacitors and maybe a 3.3V zener in parallel with the capacitors. The capacitors should buffer the voltage to the prop in case there are any short spikes, and the zener should further keep the voltage from rising above the nominal voltage.

    However, I wouldn't think there would be anything to worry about. If the battery is still putting out a good bit of juice, then there shouldn't be much of a voltage drop(brownout) either. Heck, try it and see. With the Prop being $7.99 now, it's almost disposable!
  • mctriviamctrivia Posts: 3,772
    edited 2009-04-05 05:51
    better to use a diode and cap to stop brown outs from getting to the prop. will not damage but may restart.

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    Need to make your prop design easier or secure? Get a PropMod has crystal, eeprom, and programing header in a 40 pin dip 0.7" pitch module with uSD reader, and RTC options.
  • Carl HayesCarl Hayes Posts: 841
    edited 2009-04-05 13:14
    mosquito56 said...
    ·Will it damage the prop system to have it on when an engine is started? The power suppy is the engines battery. Assumes the battery is in good condition. Obvious a bad battery droping below 5 volts will reset the system.

    It could subject the Prop to an inductive kick from the starter & solenoid if there isn't sufficient regulation and filtering between the battery and the Prop.· But surely you're not using the Prop's internal regulator in such an installation, are you?

    A more subtle danger is that a kick could be delivered through the ground system.· The negative supply lead should go directly to the battery's negative terminal, not be grounded to the body or frame.· Those often are quite poor grounds with a lot of resistance.·

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    · -- Carl, nn5i@arrl.net
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