Modifying a spy microphone's power source for leopard conservation

Discussion in 'The Projects Forum' started by kra21, Jun 14, 2016.

  1. kra21

    Thread Starter New Member

    Jun 14, 2016
    3
    0
    Hi everyone,

    I'm looking to attach a spy microphone to leopard radiocollars and have it record continuously for 1 month.

    Why? Well, for my project I'm looking at whether strategically played competitor sounds could be used to manipulate leopard movements in order to reduce conflict with people. But I need to know how vocals naturally affect their movements.

    I'm looking to hack the EDIC-Mini-Tiny B47 microphone (see attachment) so that it connects to a power source that powers it for 600 hours (its storage capacity). It's current battery life is up to 168 hours.

    I'm out in the African Bush right now, and so I would need to know whether this hack is possible and, if so, would be looking to team up with someone who can advise me on how to make the modifications.

    Weight is a major limitation here, and I would need a battery solution which weighed < 75g.

    Price is also an issue as the project budget is already stretched. So, I would be looking for a battery solution which was preferably < $50 (although, higher priced options would be considered).

    Can anyone help?

    Thanks,

    K.

    Disclaimer: I am an electronics newbie and internet access here is limited, but I am a keen learner.
     
  2. Marley

    Member

    Apr 4, 2016
    144
    40
    So you just need a larger (higher capacity) battery. These should be primary batteries (not rechargeable).

    How do you fit the batteries at the moment? Unscrew one of the end caps?

    What about making a dummy battery that is the same size as the three internal cells but has a pair of wires coming out. You would need to carefully drill and seal the end cap to get the wires out. Connect these to a larger battery pack on the animal's collar. Standard alkaline cells are good (Duracell) either AA or C size. Think judging from the spec sheet, you will need 3 of these. Weight might be an issue. You might be able to use a single non-rechargeable lithium cell. These give about 3.6V per cell. Also available in AA size. Example
     
  3. kra21

    Thread Starter New Member

    Jun 14, 2016
    3
    0
    Hi Marley,

    Thanks for your message.

    The microphone itself would probably also be removed from that casing and then put in a custom housing. I think at the moment it's just a case of unscrewing the ends.

    So, is it just a case of understanding the power required to run the microphone for 1 hour, extrapolating that to get the power required for 600 hours, and then finding a larger battery which holds that amount?

    Would connecting the the microphone to a larger power source potentially fry the device, or do you think there would be something in the device which regulates incoming power regardless of how much the battery can hold?

    Cheers again,

    K.
     
  4. Marley

    Member

    Apr 4, 2016
    144
    40
    A larger capacity battery will not damage the device providing the voltage is not greater than the existing battery.
    So you currently use 3 zinc-air cells. I think these are about 1.2V per cell giving a total voltage of 3.6V. So if you replaced with a single lithium cell of 3.6V that will be OK.

    You need to look up the specification of these cells you are using. Somewhere you should be able to find out the stated voltage and the capacity. The capacity will be stated in mA/h (hours of life with a load of x milliamperes - halve the current, the life will double - roughly). The spec should also have a graph of voltage over time with a constant load. You will notice that the stated voltage is when unused. It will drop over the life of the cell. So the device must be able to work with a reduced voltage.

    So, for example if each cell is 1.2V (new) and 100mA/h (don't know, just guessing). Then the battery of 3 cells will be 3.6V 100mA/h (the capacity does not increase with number of cells). If this gives you 160 hours use then an external battery with 1000mAh (or 1A/h) will potentially give 10 times the life.
     
  5. kra21

    Thread Starter New Member

    Jun 14, 2016
    3
    0
    Ah, okay that's great!

    I will look up those specifications as you suggested and then work out what capacity of battery I require.

    Thank you again.

    K.
     
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