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Adding a second battery to my tablet

Discussion in 'Power Electronics' started by bbkb, Jun 24, 2012.

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  1. bbkb

    bbkb

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    Jun 24, 2012
    Hello,

    First time poster here.
    I have an Arnova tablet and the battery life is pityful. Out of interest i opened it up and saw there is space for a second battery.

    Is it as easy as wiring a second battery in? The current battery is 3.7v and 4700 mAh.
    Its 3.5 mm thick but i suppose about 8cm by 8cm. Could i wire in a second one of these or would getting a higher mAh help better?

    May not keep the tablet though, the worst typing experience ever.:confused:

    Thanks
     
  2. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Batteries in parallel will increase the available current, thus in this case if you hooked up another 3.7v @ 4700mAh battery you would get 3.7v @ 9400mAh or roughly twice the run time...

    You can likely just hook up a 2nd battery in parallel with the first this will improve run time but the built in charging circuit will likely complain or fail to work properly with both batteries attached... It might not complain but you just never know, most integrated Lipo chargers are smart chargers that use a feedback line (temp sensor) designed for a single battery, some don't employ this so you might be OK... If they employee the third line there is not practical or easy way to get them working properly in parallel... But the short of it is that you very well might have a charging issue that will be a bugger to get working properly... This is the reason why you see most 'extender' batteries just plugging into the charging port to simulate a charge...

    Be mindful that improperly charging Lipo batteries can result in fire/explosions...

     
    Last edited: Jun 24, 2012
  3. axeteve

    axeteve

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    0
    Jun 28, 2012
    @bbk Wow! so I'm not alone who want to add extra pair of batteries to the arnova tablet :)

    @coca I think they are not lithium - polymer instead they are 3.7 volt 3700mAh lithium - Ion batteries. The entire china use the same batteries for all the Chinese tablets.

    And I don't think they got are with protected circuit. Though I'm not sure.

    I've few questions. OP might also get benefited with the answers.
    1. What I take these off and instead connect five 3.7V 2400mAh TrustFire protected Li-Ion Batteries in parallel.
    So it'll be around 3.7V 12000mAh
    2. The Charging system /circuit should not be complaining as the charging voltage is same I.e- 3.7Volt only thing is that it should take longer time to fully charge it. Am I correct on this analogy?
    3. And what can go wrong in this mod..?

    Regards
    Max
     
    Last edited: Jun 28, 2012
  4. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    As I said, one in the same...

    "Lithium-ion polymer batteries, polymer lithium ion, or more commonly lithium polymer batteries (abbreviated Li-poly, Li-Pol, LiPo, LIP, PLI or LiP)"

    I'm sure that they will have some protection it's just a matter of what kind and to what degree it's employed... No legit/honest company is foolish enough to not employ protection in a LiPo charging system...

    It would run fine but charging could (will likley) very well be an issue...

    Incorrect, without knowing more about he charging system you can simply not assume anything of the such, doing so is simply irresponsible and dangerous in this case...

    See the video in my previous post...

    <~ This is REALITY and does happen with LiPo cells when charging goes wrong!

    The short of it, if you don't understand the technology behind LiPo batteries and the proper way to charge them it's best you don't pretend to know and possibly cause serious bodily harm...
     
    Last edited: Jun 29, 2012
  5. axeteve

    axeteve

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    Jun 28, 2012
    :( So conclusion is I can't increase the battery capacity ... Or there is some kind of solution is possible I.e. - After properly evaluating the charging input output current-voltage etc. using multimeter.

    There has to be some way :[
     
  6. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    No the conclusion is you can't simply ram a different or extra battery in there and expect it to work without issues... You need to identify the charging circuit and it's mode of operation and either redesign/replace it so that it works or use a battery that is within it's existing capabilities...

    It's likely going to take more then a multimeter in most cases... You need to identify the charging circuit and how it works, it's limits, and also what kind of feedback it's getting from the batteries when charging...

    There is, but it has to be done properly not in haste or half $%@ed...
     
    Last edited: Jun 29, 2012
  7. axeteve

    axeteve

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    Jun 28, 2012
    just because these are lipo batteries or the proper current voltage distribution parameters are required.

    But I see people casually charge and use-reuse their AA or AAA batteries in camera and even children toys... Or NiMh or NiCad are different.

    I never thought of this safety perspective of small batteries.
     
  8. CocaCola

    CocaCola

    3,635
    5
    Apr 7, 2012
    Using them and charging them are two entirely different things...

    A lot of people don't but they should...
     
  9. davenn

    davenn Moderator

    13,802
    1,941
    Sep 5, 2009
    yes NiMh and NiCd batteries are different from LiPo's they have their own style of charging
    which if not followed correctly can also lead to exploding batteries

    Dave
     
    Last edited: Jun 29, 2012
  10. axeteve

    axeteve

    4
    0
    Jun 28, 2012
    Thankyou all, For the valuable information.

    You Guy's got a very nice forum, I'll be visiting more often.

    :)
     
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