Portable Battery Pack

Discussion in 'Technical Corner' started by Banjo33, Jun 9, 2019.

  1. Banjo33

    Banjo33 Line Up and Wait

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    Looking for recommendations for portable battery pack for airplane camping. Enough power to inflate an air mattress (once, but possibly top off once per day), run a small fan over-night, charge electronic devices, etc. Might be able to recharge it every other day or so.

    Last I read, solar panels are pretty hit or miss still?

    How effective would a spare car or airplane battery with an HF inverter be at this?
     
  2. chartbundle

    chartbundle Cleared for Takeoff

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    Aren't we having this discussion on the other group...

    Outside of a couple months of the year in Alaska you'll have trouble running a fan at night with a solar panel. But, they do make good solutions for keeping the battery pack charged.

    I'd not even consider a wet cell battery. A Sealed Lead Acid/AGM/Gel Cell would be fine, but the power densities are low, and inverters can be inefficient. At the end of the day I recommend doing MATH, figure out how many Watts each device takes, and how many hours you need it for between recharges then multiply each together and add them all up, and then add at least 30% for the Inverter, then double it to not overly discharge the battery and then you have the battery Watt Hour capacity. Then multiply the battery amp hours by the voltage if the battery doesn't provide watt hours directly.

    For actual batteries, you can roll your own. Goal Zero makes some nice Lead Acid and Lithium systems at stupendously expensive prices. I have a '500' Wh Lithium pack from Suaoki with built in inverter and Solar charge controller.

    I'm fairly comfortable with taking it in the plane with a few caveats: Never discharge or charge in the plane. Never fly with it fully discharged or charged(shoot for 80-90%). Don't take it right off the charger and take it flying, let it relax and cool first. Don't take it flying after midnight. Never transport it damaged. Make sure it's secured to not bounce around. Keep it out of the sun(especially when flying)
     
  3. hindsight2020

    hindsight2020 En-Route

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    LOL Jesus, it's like owning a f------ Gremlin. :rolleyes: Other than the shooting how was the play Mrs. Lincoln?

    Reminds me of the LO 5th gen MIC-special, major weapon systems we've procured. They can shoot a Chinese fighter from 60,000 feet and nobody knows they were there, but don't get the paint wet or cross the IDL lest the thing goes blue screen on you. Oh and hold your breath when high, the OBOGS might choke you out :D
     
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  4. Banjo33

    Banjo33 Line Up and Wait

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    Thanks for the thorough reply. I mentioned the airplane battery as I have an old GIL that came out of my plane that’s still good, so I use it as a spare when doing Mx. But, if that and a cheap inverter won’t do the job, I’ll keep looking.

    I’ve pulled the numbers of the air pump and fan that I’ll be using. I don’t think the power requirements are high, but haven’t exactly figured out the calculators to determine what I need. Volts times amps= watts?

    For instance,
    All 120vac
    Fan: .35 amps for 10 hrs/day (3.5 amps)
    Pump for air mattress: 1.4 amps for 2 minutes/day (call it .1 amp).

    42 watts/hr?

    Looking at a portable power pack, a relatively cheap one is capacity rated at 167 watt hours.
    This would run my gear for just short of 4 hrs before needing a recharge?
     
  5. chartbundle

    chartbundle Cleared for Takeoff

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    Yes, 42 watts for the fan.(it's not watts per hour, just watts, then you multiply by the number of hours you need to get capacity)

    0.35 A * 120V * 10hrs = 420Wh
    1.4A * 120V * (2/60) Hrs = 5.6 Wh

    So, before inverter and battery losses, 425.6 Watt Hours for your daily number.

    A typical Aircraft Battery (using my plane as a reference) 35 Amp Hours * 12V for 420 Watt Hours.

    And they don't like being fully discharged.
    There are other lead acid designed for deep discharge, but I think refactoring the problem is a better idea.

    So, can you get a better fan, maybe 12V or something smaller or more efficient.

    Also, maybe the fan doesn't use 0.35A the whole time, maybe just on startup, do you have a measuring device that can actually tell what the steady state load is.