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DIY bluetooth speaker

Discussion in 'Power Electronics' started by commander768, Apr 7, 2019.

  1. commander768

    commander768

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    0
    Jul 18, 2014
    Hello, i need some help with making diy bluetooth speaker. I already ordered TDA7492P 2x25W amplifier/bluetooth module. It works with 10-25V. What i need now is power suply (batteries), battery circuit protection and charging module. I am buying it all from ebay (except batteries which i already have).

    So can you help me with advices as to what to buy. I am thinking of ordering this protection board, i would use 6 batteries giving me 25.2V at full charge. But now i need a charging board that will handle 25V 2A and has got to have microusb. Any advices ?
    [​IMG]
     
  2. BobK

    BobK

    7,606
    1,647
    Jan 5, 2010
    Why does it "got to have micro usb?" Using a USB connector for 25V is ill advised. Also, you will need more than 25V to charge a 6S Li Ion battery. What does the battery management board call for? Can you provide us a link?

    Bob
     
  3. commander768

    commander768

    39
    0
    Jul 18, 2014
    Thank you for your reply, i ordered this board for 5 batteries and total of around 22V:

    https://www.aliexpress.com/snapshot...orderId=100453530446465&productId=32815500275

    The reason i wanted to have microusb is so i could charge the speaker with a power bank. But ok, it is not necesary. Now i have amplifier/bluetooth, i have battery management board. Now i need a way to charge this batteries, 5 batteries in series. Is there a cheap way to do that ? At home i have plenty of sources of different DC voltage. As it is right now, i would have to individualy charge each cell (i have a 3.7V li-ion charger for 4 cells at once), it would be easier to just plug the speaker in and charge without removing cells.
     
  4. Hopup

    Hopup

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    30
    Jul 5, 2015
    I would suspect it would be easiest to use just one big battery thus charging it would be simple
     
  5. BobK

    BobK

    7,606
    1,647
    Jan 5, 2010
    Link brings you to a login screen. Link the ad, not your order status.

    Charging off a power bank does not make much sense unless it has more power than your speaker supply, which most do not. If you really want to do that, you could use a step up converter run off the powerbank, but it would have to be able to provide about 12A at 5V. I think that is beyond what a usb connector can do.

    Bob
     
  6. commander768

    commander768

    39
    0
    Jul 18, 2014
    It would, but i dont have 1 big battery, only 18650 cells and the whole point is to use them
     
  7. commander768

    commander768

    39
    0
    Jul 18, 2014
  8. Hopup

    Hopup

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    Jul 5, 2015
    If it were me I would not charge them in series to begin with, just make battery slot to plug them in an out and use proper charger. Not the smartest thing to make cheap ass diy 18650 charging circuit.
     
  9. commander768

    commander768

    39
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    Jul 18, 2014
    Ok, what if i make individual connection to each of the battery and charge them this way ?
     
  10. Hopup

    Hopup

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    Jul 5, 2015
    Just make sure to have enough wire thickness and low resistance, it should work just fine. I would myself think as having removable cells definite plus side. There is no significant difference in time for taking the cells out or keeping them in if you design it well.

    Extending the time for a playing music would be just replacing couple of cells which is obviously better than charging the battery if u would want to keep playing longer.
     
  11. commander768

    commander768

    39
    0
    Jul 18, 2014
    OK i draw something and i need you to tell me if this would theoreticaly work. Or do i need a button that will cut off the connection between batteries and amplifier when i plug in the charger.
     

    Attached Files:

  12. Hopup

    Hopup

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    Jul 5, 2015
    Not necessarily but I would recommend doing that. Don't really want to comment much about that chinese thing without even having proper datasheet.
     
  13. commander768

    commander768

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    Jul 18, 2014
    Lets say for now that we belive that chinese board. I decided to place a button to + wire between battery and amplifier. That way i can turn the whole thing off and also i think it would be better/safer for charging. Still, i am curious, what would happen without a button ? Would it charge at all or what ?
     
  14. commander768

    commander768

    39
    0
    Jul 18, 2014
    bump
     
  15. commander768

    commander768

    39
    0
    Jul 18, 2014
    Well i will have 5 cells in series but now i have to decide whether to charge them in series, or just charge each 1 individualy, that would mean 5 cheap chargers for lithium cells, and then just connect them to the same power source. Any thoughts on that ?
     
  16. dave9

    dave9

    765
    170
    Mar 5, 2017
    I would own an 18V cordless tool collection and use a battery pack from that, and charge it with the intended charger. I'd buy the cheapest tool I could find with that battery interface to cannibalize it for the mechanical connection, a dead for parts tool off ebay or something from a pawn shop, or a flashlight, etc., except some of the larger tool brands already make a bluetooth speaker that (obviously) takes their batteries.

    However since you already have the cells... I wouldn't base a project around that, would use them in flashlights or something.
     
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