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Portable AA battery supply to act as a charger as well?

Discussion in 'Power Electronics' started by MKANET, Jul 14, 2012.

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  1. MKANET

    MKANET

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    Jun 3, 2012
    I have a cheap portable 2 AA battery supply (below picture) that's used to power some devices such as portable phones, electric shavers, etc.

    Im just curious... If I use rechargeable batteries in this power supply, I thought it would be very convenient if I had a way charge the batteries without taking them out of the enclosure.

    So, ideally, I would first remove the currently plugged in cable in the pictures that's meant for powering devices. Then, I would use AC wall charger that has an 1/8" male minijack plug on the end of it's cable which would plug into the enclosure instead to charge the batteries.

    Once I'm done with charging the batteries, I could replace the cable again. Of course, even if this did work, I dont know how I would know when the batteries are charged.

    Sorry if this sounds like a very stupid thing to do. I don't know anything about electronics. All I know is it would be really convenient for me.

    [​IMG]

    [​IMG]
     
    Last edited: Jul 14, 2012
  2. mechtronics

    mechtronics

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    Aug 7, 2011
    AA batteries normally take about 3 hours or more to charge anyway depending on the type of batteries being used i presume ul be using energizer ones!!. you would have to use the likes of a phone charger in order to do this, which would have around the 3.5 volt to 4.5 volt output depending on the current rating of the batteries to be charged. with the same jack used as in the picture.
     
    Last edited: Jul 14, 2012
  3. MKANET

    MKANET

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    Jun 3, 2012
    So, does that mean it can be done? I definitely know that it takes 3 or more hours for my rechargeable batteries to charge using my other charger. It just doesn't make any sense to take them out from one enclosure and put them in another and back. Especially if it needs to be done relatively frequently. Just not sure what involved to get the item in the picture to act as a battery charger as well.

    Seems like a practical device to have. Maybe there is already a consumer device that does this already? If not, just wanted to know if its possible to do. Maybe not be me, but someone who is an electronics guru. Sorry if this is completely impossible. I just thought it would make sense to be able to do.


     
  4. mechtronics

    mechtronics

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    Aug 7, 2011
    is there any circuitry in the device thats in the pic?? as in pcb board?
     
  5. MKANET

    MKANET

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    Jun 3, 2012
    Yes, definitely. The device, once connected to a mobile phone, started to flash it's leds after 10 second to indicate it's providing power to the device and charging it.

    If I connect it to a USB device, after 10 seconds, it starts to power the USB device.

    Below, is the best picture I could show of it without trying to disassemble the other end...

    [​IMG]



     
  6. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,477
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    Jan 21, 2010
    The device is a boost switch mode power supply. It takes the input voltage (probably down to 2V -- or lower if the batteries are NiCads) and boosts it to 5V.

    In theory, you need to add another jack on this device which connects to the two contacts ont he PCB of this device. You would plug it in to your charger (again you'd have to make a lead and attach it to an appropriate place in the charger. Your charger would have to be one that charges batteries in pairs.

    You may have problems with the voltage from the charger "upsetting" your power supply. If this happens, you could use a switching socket to disconnect the batteries when they are being charged (this would also eliminate the possibility of the device damaging your charger).

    Whether or not you have room to fit such a socket in the device is hard to say -- I'd guess not (but you could do it with an external lead too). Whether or not you have a charger that charges cells in pairs is another issue, but that's pretty easy to determine and most cheap chargers seem to be like that anyway.
     
  7. MKANET

    MKANET

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    Jun 3, 2012
    Steve, thanks so much for taking the time to explain. I think by the way you describe, it sounds like it might be possible with the right person trying it.

    Thanks!

     
  8. mechtronics

    mechtronics

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    Aug 7, 2011
    ya steve just answered the question for me haha! thats the reason i was asking about the PCB board. but ya you will have to add another jack to it and connect it to the circuitry on the PCB board which will be very tricky to incorporate onto it. good to see people putting pics up they help so much.
     
    Last edited: Jul 15, 2012
  9. MKANET

    MKANET

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    Jun 3, 2012
    in theory. If there was some more room to transplant a separate charger's pcb into the enclosure in the pics above (in addition to the existing pcb), would it be possible to share the same jack? I could then have two different cables that could be plugged onto that jack... one meant for providing power and another one with a USB plug on the other end meant to charge the batteries.

    This sounds like an extremely convenient two in one device. I was hoping that maybe somthing like this could be made using a different enclosure and spare parts from existing products.

    Impossible?
     
  10. mechtronics

    mechtronics

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    Aug 7, 2011
    if that was the case all you would need to do is, if you wanted to put a USB onto it u could use that for charging the actual chargers batteries, provided the connections for charging are connected to the right place on the pcb. and then just use the regular output jack on it already for powering auxiliary items. but this is only in theory in practice you would probably have to make a new one with a different design as the charger in the pic is not very spacious.
     
    Last edited: Jul 15, 2012
  11. MKANET

    MKANET

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    Jun 3, 2012
    Thanks for replying mechtronics, but it doesnt look like you understood what I was trying to say. Or, maybe you did? Even with pictures, sometimes it's hard to explain. :(

    This is what I was proposing in my post before yours (two different cables that can plug into the enclosure's single 1/8" mini jack).

    This cable is used to charge the batteries
    <--[1/8" male mini plug]--------------------------------------[male USB plug]---->

    This cable is used to power my mobile phone or whatever it is
    <--[1/8" male mini plug]--------------------------------------[charger plug for power]---->


    Depending on the function, the proper cable would plug into the enclosure's single female 1/8" mini jack.

    This would consolidate everything into one small compact device with one jack only.

     
    Last edited: Jul 15, 2012
  12. mechtronics

    mechtronics

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    Aug 7, 2011
    i think that you are making it more awkward than it is. when u say a separate charger pcb do u mean for charging the batteries in the device? i would just add a separate charging jack onto the existing pcb to charge the batteries themselves and just use the output that u have on it already for powering other devices when the batteries are finished charging.
     
  13. mechtronics

    mechtronics

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    Aug 7, 2011
    i see what you want to do. you might be able to use the one jack with two different cables. you would have a mains charger from 230 V AC to roughly about 4V DC. this would plug into the jack, but you would have to use wire and jump the connections from the jack on the pcb to the battery connection terminals inside the housing. and you would still be able to use the wire in the pic to power auxiliary items. my main concern is when charging the batteries from the same jack could damage the pcb board. you wouldnt need usb.
     
    Last edited: Jul 15, 2012
  14. MKANET

    MKANET

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    Jun 3, 2012
    I don't know why I didnt think of this before. Isn't there a power consumer product that holds a lot more capacity than the one in this thread? The batteries dont have to come out. They can just be a powerpack that's meant to power similar devices as the one in this thread; with the exception it can last A LOT longer. Basically as long as possible without the battery being bigger than a pack of cigarettes.

    I was so focused on having the same plug, I didnt realize that I could just buy something that ultimately does what I need it to do (can charge it's internal battery, can provide long lasting power to a device). In a worst case scenerio, all I would have to do is change the plug on it that's used to power my device; since it is a very specific size.

    Thanks for any suggestions. I'm not sure what consumer products to look at since i dont know what type of specs to search for in google for it to show up.

    MKANET

     
  15. MKANET

    MKANET

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    Jun 3, 2012
  16. mechtronics

    mechtronics

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    Aug 7, 2011
    I reckon that should do the trick you have a lot more capacity too so it will last longer. a lot easier to just buy one off the shelf!!
     
  17. MKANET

    MKANET

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    Jun 3, 2012
  18. mechtronics

    mechtronics

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    Aug 7, 2011
    ya usb is 5 volts output up to 2A.

    should do the trick for u.
     
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