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powering camera with usb battery

Discussion in 'Power Electronics' started by ronrice, Jan 3, 2018.

  1. ronrice

    ronrice

    3
    0
    Jan 3, 2018
    i dont want to blow up the camera. here is the situation:

    camera battery is 3.7vdc.
    aux external ac power kit 4.3 vdc

    can i hook a usb power cord at 5vdc to the camera without damage?

    usb cord hooked up to 15000 ah battery pack.
     
  2. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    Assuming the battery pack is lithium based, the 3.7V battery may be 4.2V fully charged.
    That's mighty close to the external AC power kit, which concerns me because the charging circuit *could be* an overly simplistic one to save on build costs.
    A higher voltage supplied to this device to charge it could damage the battery... either by over-charging it to a voltage that is too high, or charging it at too fast of a rate.
    Hopefully the charge circuit in the camera does current and voltage regulation/limiting, but I can't say for certain. It's good practice to have this capability, but not all good practice is followed in the quest for higher margins, and lower build costs.

    So.. What model is your camera?
    I assume you are looking to modify a wire to go from USB to some other form of plug to the camera? (If not, how does the camera charge? Some cameras will charge through USB, in which case 5V is *expected* on the USB connector)
     
  3. Audioguru

    Audioguru

    2,618
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    Sep 24, 2016
    Lithium burns violently. If you connect 5V USB to a 3.7V lithium battery then it will overcharge, explode and catch on fire.
     
  4. ronrice

    ronrice

    3
    0
    Jan 3, 2018

    thanks for the reply. sorry i was not clear enough. I want to hook my pocket juice 15000mah pack that has an out put of 5vcd directly to the camera (bypassing internal camera battery) that is designed for a battery that puts out 3.7 vdc. i am worried it may overload the internal camera voltage regulator, but then again its only 1.3 volts more than its is expecting. camera is a powershot by cannon sx520hs.

    what i want to do is to shoot video continuously for 2 hours at a location with no ac outlets.
    i have a ac power adapter kit that has a black battery case attached to a cord to a ac adapter. the adapter puts out 4.3vdc. i want to put the pocket juice batter pack in place of the adapter
     
    Last edited: Jan 4, 2018
  5. davenn

    davenn Moderator

    13,347
    1,774
    Sep 5, 2009
    this is not a good idea, specially this part

    and that is the reason why

    what is the normal input voltage to the camera from an external AC-DC plugpack ?
     
  6. ronrice

    ronrice

    3
    0
    Jan 3, 2018
    4.3vdc
     
  7. davenn

    davenn Moderator

    13,347
    1,774
    Sep 5, 2009
    OK
    sorry, I missed that in your first post
    so putting 5V directly in there isn't s good idea it's quite probably that the camera may not be able to handle the extra 0.7V

    I would use a DC-DC buck converter to drop the 5V from the battery pack to the 4.3V required by the camera DC input.

    here's one of the 100's of examples available ....
    http://www.ebay.com.au/itm/DC-DC-St...&sd=151956763551&_trksid=p2047675.c100623.m-1



    Dave
     
  8. Gryd3

    Gryd3

    4,098
    875
    Jun 25, 2014
    I tend to look at things from a % stand-point as opposed to a number value...
    An extra 5V won't matter to a household appliance as they run at over 100 (or 200 depending on where you live)...
    But an extra volt may make all the difference for smaller electronics. 4.3V to 5V is more than 10% which is usually my *concerned* threshold. If you have a 4.5V adaptor then go for it... 5V is *probably* a little too risky. No way to know for sure without looking at the schematic/parts.

    What you *can* do though... and it's much cheaper and simpler than a buck-converter... is to use a diode inline with your power supply. It should drop 0.7V, which will bring the 5V down to 4.3V which would be a perfect match... the downside here though is that this is wasteful... as the extra energy is simply burned off as heat (or warmth) . The more power your camera draws, the warmer the diode will get.
    If you have a high power requirement... avoid the diode method, and go with a buck converter.
     
    davenn likes this.
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