Trying to make a battery that doubles capacity

Discussion in 'The Projects Forum' started by Dimrain13, Oct 14, 2011.

  1. Dimrain13

    Thread Starter New Member

    Oct 14, 2011
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    I will have two batteries both are the exact same size and output. I'm trying to get them linked in parallel


    Picture here: http://imageshack.us/photo/my-images/511/6272931610408.jpg/

    This is an attempt to double the battery life of an android tablet, if this works out anyone that helps out will also get credit for this build.

    My main thought is that double amps might hurt the circuit board in the long run. so if i have two hook together..(soldering the wires together) you knw the rest. i do nt have my hands on it yet but i plan to in the next 4 weeks.
     
  2. Georacer

    Moderator

    Nov 25, 2009
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    How do you plan to fit those batteries in your tablet? Are the two batteries you have made for that specific model?

    I don't see why this shouldn't work. If the voltage rating is correct, there shouldn't be any strain in the board.
    What I am concerned about is that the tablet will be confused about its battery's unnatural power reserves (and hunger while charging) and this may cause some software problems.
     
  3. Dimrain13

    Thread Starter New Member

    Oct 14, 2011
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    one i get it iplan to make a fiberglass rear shell with everything connected to ensure the ccorrect size.. and i thought that i would have to worry about the amps more than the voltage. the type of tablet is the ASUS transformer because the add on keyboard comes with a second battery that i intend to use (they are the same)i plan to hook u the batteries in a non-conventional parallel the positive and negative ins and outs, but because they are color coded i plan to make a small strip in the wire and connect the tips of the same color and solder..
     
  4. SgtWookie

    Expert

    Jul 17, 2007
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    That's a Li-Ion battery.

    Due to safety issues, I advise you to not attempt your modification idea. Li-Ion batteries can suffer thermal runaway if overcharged or overheated. Placing two flat batteries together in a package will decrease the ability for each battery to radiate heat by at least 50%.

    Also, there are temperature monitoring circuits connected via the battery harness. You would need a way to make certain that if either battery had a rise in temperature, that the charging would be discontinued. It would be difficult to determine what the circuit is doing without dismantling a battery for inspection; then a circuit would need to be devised to ensure that both batteries were monitored.

    I'll suggest that this is not a project for a beginning hobbyist.
     
  5. #12

    Expert

    Nov 30, 2010
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    Some of the answers about amps: Batteries do not force their rated amps into the load. They provide voltage. The load decides how many amps it needs.

    Then there is the charging side. Li-ion batteries are notoriously picky about charging. A charger designed for one battery can cause serious problems if connected to double what it is expecting.

    I think...don't.
    Not unless you can account for how the charger works, heat dissipation, and software that is trying to monitor charging and reserve capacity.
     
  6. iONic

    AAC Fanatic!

    Nov 16, 2007
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    Not a good idea. As stated above, the tablet may run longer once, but when it comes to charging no one knows what will happen, not to mention the tablets software seeing an odd battery capacity present. Also, Sgt. Wookie's concern about the battery chemistry and its safety records is well founded.

    The way I see it:

    1) Use the wall adapter
    2) Use the tablet less and live a little more

    For me I'm going with option 2.
     
  7. wayneh

    Expert

    Sep 9, 2010
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    Keeping another battery pack or two to swap out is a much simpler approach. Making yourself another charger, that would charge the extra packs outside of the tablet, is much closer to a DIY project.
     
    Georacer likes this.
  8. Dimrain13

    Thread Starter New Member

    Oct 14, 2011
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    Is there anything that you could think of that would make this work? i could move the battery over a bit or make the backing thicker or with vents.. im not worryedabout the over heating.. but the charging would be the issue.. i could make my own charger for it .. im not worried for the android freaking out because i have used bigger batteries in my Galaxy S... any ideas.?
     
  9. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Making a switch over to a standby battery means turning off the computer and installing the extra battery. IF you could switch over to a standby battery by connecting them in parallel(VERY briefly) and switching out the depleted battery. Then it might work as you envision. Needing extra operating time while mobile is a common theme.

    You would still need to let the computer charge the batteries ONE at a time, not together. The switching between batteries without losing power will require some rewiring that WILL void any warranties you have, but the concerns for charging will be addressed by keeping OEM original battery packs and OEM original charging circuitry.
     
  10. iONic

    AAC Fanatic!

    Nov 16, 2007
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    Do as wayneh suggests in post #7. Just save any open work, restart with fresh battery.
     
  11. Dimrain13

    Thread Starter New Member

    Oct 14, 2011
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    what type of switch would be able to switch and not let the power go out? it would have to control 8 wires at once per battery. this idea is the most ideal since do not wish to open the tablet again.
     
  12. Adjuster

    Well-Known Member

    Dec 26, 2010
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    There are portable battery packs sold that can emulate a mains charger (for a limited period of time). This is an example: I do not endorse this product in any way, actually it seems expensive for what it offers, but at least it is an off-the-shelf item.

    https://powertraveller.com/iwantsome/primatepower/powergorilla/

    If you can get one compatible with your tablet, this might be better than trying to bodge something which might literally blow up in your face.
     
  13. Georacer

    Moderator

    Nov 25, 2009
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    It was about time battery technology caught up with the 21st century. I hope this can stand up to its promises.
     
  14. DickCappels

    Moderator

    Aug 21, 2008
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    SgtWokie's points are (as always) valid. Li-ion battery charging is very dangerous for those who are not experts in the filed; one cannot over-stress the dangers. I suggest that you find another (safer) project.
     
  15. SgtWookie

    Expert

    Jul 17, 2007
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    Perhaps you'd change your mind when it burst into flames while sitting on your lap?
     
  16. #12

    Expert

    Nov 30, 2010
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    Failing to understand is dealt with every day. Refusing to understand is beyond the scope of our powers.
    The terms of service on this site forbid us from giving advice on a project that is likely to hurt somebody.
     
    Last edited: Oct 15, 2011
  17. SgtWookie

    Expert

    Jul 17, 2007
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    It's all too frequent that someone relatively new to electronics wants to do something that they are virtually certain should be quite easy to accomplish, if they just had a little bit more information; and forget about the naysayers.

    Here is a video of a laptop powered by a Li-Ion battery that had thermal runaway artificially induced:
    http://www.youtube.com/watch?v=pizFsY0yjss&feature=related

    This type of situation would rarely occur in an unmodified consumer product, as they have been carefully engineered to prevent such a disastrous/catastrophic meltdown.

    However, if you start tampering with the device, the likelihood of you experiencing something like this first-hand increases dramatically.

    Along with the hazards you'll expose yourself to, you also need to know that lithium fires are very difficult to extinguish, and the fumes are hazardous. It is 3 fires in one; electrical, chemical, and metal, and burns at a temp exceeding 1,000°F.

    From the YouTube post:
    [eta]
    Here is another video on YouTube put out by the FAA, regarding extinguishing laptop fires on aircraft.
    In the first minute of the video, a laptop fire and explosion that occurred at Los Angeles International Airport is shown.
    http://www.youtube.com/watch?v=vS6KA_Si-m8
     
    Last edited: Oct 15, 2011
    vrainom, Georacer and #12 like this.
  18. iONic

    AAC Fanatic!

    Nov 16, 2007
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    Last edited: Oct 15, 2011
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