Good Battery Replacement for non motor functions

Discussion in 'Cinestar 8' started by Steven Flynn, May 22, 2015.

  1. Steven Flynn

    Steven Flynn Member

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    Hey everyone.

    I have a question. I've been powering my onboard accessories (hair dryer, toaster, and seat heater) with those blue Hyperion CX G3 lipo packs. The 4S 2500mah version. I just fried my last one (left it on after a shoot because the clients were so happy they got in and talked my ear off and I forgot to shut my power down)...

    Anyway, I love running my transmitters, converters off one battery (makes everything so much easier), and I'm wondering if anyone has a good suggestion for a replacement given my power needs are not High Current needs. I need to sustain at least 12 volts (I have a 12volt mini converter to maintain proper voltage) to video downlink, cameras, hdmi converter etc... but not to movi, still use that as a solo dedicated battery.

    Any thoughts from the better engineers than me? Any battery lighter and cheaper, or is the "blue block" the best solution?

    As always, thanks.

    Steve
     
  2. Gary Haynes

    Gary Haynes Administrator
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    Steven I use the inexpensive Zippy's from HobbyKing for that type of stuff. They do fine, don't cost much and I agree that Hyperions would be overkill.
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Given that your hair dryer is not flight critical, I agree with Gary -- basically any 3S or 4S battery can be used depending on the setup you have. In some cases I'll drive the accessory directly from the LiPo (given that it can tolerate the voltage range) and just use a 5V Recom DC/DC converter to get 5V DC for those devices that need it. At 4S the 5V Recom gets a little hotter as it has to drop the voltage more.

    You'll get longer life from the battery if you tough it out without the seat heater, though. ;)

    Andy
     
  4. Steve Maller

    Steve Maller UAV Grief Counselor

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    I'd recommend looking into this battery:
    http://www.hobbyking.com/hobbyking/...d_11_1v_3s_2200mAh_1_5C_Transmitter_Pack.html
    It's 3S (12V, more or less) but has a low voltage cutoff to prevent it from committing LiPo hari kari. You don't need a big 'C' rating for FPV stuff, so there's no need to get a fancier LiPo. Just to be super methodical, I'd add up the current draws of the gear you're powering (or even do some actual measurements) and make sure you're OK with just 3 amps of current. I strongly suspect you will be fine.
     
  5. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    I agree with Steve -- a 3S is also typically a bit lighter for a given capacity...

    Andy.
     
  6. Steven Flynn

    Steven Flynn Member

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    you guys rock. I'll add up the loads and run it past you if you dont mind. I'm also powering the blackmagic production 4K (biggest camera I power), and that might top out the current draw. have a good weekend. s
     
  7. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
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    Steven: As SteveM suggests, an actual measurement of the current would be the best way to get "real world" data. The problem with manufacturers who state the current draw is that you are never really certain whether they're accurate -- or whether it's the peak current draw or the "steady state" current draw.

    But, just totting up the manufacturer's stated current draw will be a good place to start for a more-or-less "worst case" calculation.
     
  8. Steven Flynn

    Steven Flynn Member

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    I just ran an official test, and I'm drawing only about 2.8 amps at full draw. That's video downlink, 4K blackmagic in record, Blackmagic 4k-SD converter and seat heater.
     
  9. Steve Maller

    Steve Maller UAV Grief Counselor

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    The battery I suggested above should be fine based on its 'C' rating.

    Are you familiar with battery 'C' ratings?
    https://www.commonsenserc.com/page.php?page=c_ratings_explained.html
    So what does the C rating on a lipo mean? For starters, the C in C Rating stands for capacity. To break it down to its simplest terms, the C rating is the maximum safe continuous discharge rate of a pack. If you see 10C on your battery, it means it can be discharged at 10 times that pack's capacity. Capacity refers to the milliamp-hour rating of the battery, which will be listed as a number followed by mAh (2000mAh, for example).

    Here's the easy way to find your battery's discharge rate just multiply the number from the C rating by the pack's capacity. Keep in mind that 1000 milliamps equals one amp. Here's an example, using an 11.1V 2000mAh 10C

    11.1 volt 2000mAh -10C
    2000 milliamps = 2 amps
    2 Amps x 10 = 20 amps continuous discharge

    This means that you can safely draw up to 20 amps continuously from that 11.1V 2000mAh 10C without doing damage to your battery.

     
  10. Steven Flynn

    Steven Flynn Member

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    Yep. I think I'm good to go. Thanks for all da wisdom. steve
     

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