can i increase battery life by connecting 2 of these together?

Discussion in 'General Off-Topic Chat' started by xdarkmario, Feb 12, 2016.

  1. xdarkmario
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    xdarkmario Philosopher

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    im working on a little project in making a rechargeable controller. So i brought one of these batteries for it, and so far so good it works BUT i only get about 5-6 hours for full charge. i was wondering if i add a second battery would that be safe, should i just tie/soldier the corresponding wires together and charge for longer? or does it need to connected together a different way?
    DSC_0101.JPG
     
  2. Ssssuper

    Ssssuper Member

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    Yes do it.
    I'm an electric engineer and this is completely safe to do.
     
  3. Lucar

    Lucar Professional Ferret

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    I'd like to see your certificate then.

    Also, @xdarkmario it seems safe enough, don't take my full word for it though, I'm not an electrical engineer.
     
  4. pwsincd

    pwsincd Garage Flower

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    connect in parallel not series to increase life of battery . series will increase voltage and likely pop your bits :) i am an electrical engineer :)
     
  5. FAST6191

    FAST6191 Techromancer

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    Parallel wiring will work to allow you to increase operating lifetime of a device. Where the trouble usually comes in is in charging the things where one cell might charge quicker than the other and that can lead to all sorts of fun and games. I do not know if there is any charge management in the batteries you have there (only two wires but it could have some onboard) which could help with that but still be aware of the issue.

    If it is just for a simple controller and you can take a couple of seconds downtime (or less) then perhaps put a switch in there instead so it acts as two separate batteries but still on the same controller and allow you to simply flick it across when the time comes.
     
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  6. pwsincd

    pwsincd Garage Flower

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    charging the thing is a whole other conversation , if the batteries have any differences at all in characterisitics then eventually one could not fully charge or deplete and youll end up at square one. but charging them seperately could work.
     
    Last edited by pwsincd, Feb 13, 2016
  7. Duo8

    Duo8 I don't like video games

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    Apparently connecting them in parallel will negate this issue. The battery doesn't seem to have any safety circuit (those are usually on 18650 flashlight cells)
    Trust me I'm a normal guy.
     
  8. Allahu_Spooky_Cena

    Allahu_Spooky_Cena Advanced Member

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    You want to put a diode in there somewhere because otherwise the cells could discharge through each other
     
  9. The Real Jdbye

    The Real Jdbye Always Remember 30/07/08

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    I agree with what others have said about charging being a potential issue, I've only read about people doing these things and the general consensus was that if the cells are charged as one and they are not identical (in other words, don't charge/discharge at the same rate and with the same voltage across the board) then you could end up overcharging one cell or over-discharging one cell which is not something you want to do with lithium cells. Over-discharging can shorten the life of cells or kill them and overcharging can potentially cause violent reactions (think lots of heat, fire, etc.)
    In parallel? That seems unlikely.
     
  10. Allahu_Spooky_Cena

    Allahu_Spooky_Cena Advanced Member

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    It doesn't always happen, but under some circumstances the cells can develop a potential difference and one cell will discharge through the other one.
     
  11. mgrev

    mgrev Music Addict, Video Game Fanatic

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    i am 420% legit ekspert and i kan confrim connecting red to black will explode. also, connecting red to red and black to black is paralel and will work,
     
  12. pwsincd

    pwsincd Garage Flower

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    i kan konfirm red to blak wonk explode , but will deffo nae work like !
     
  13. FAST6191

    FAST6191 Techromancer

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    Come on lads; this is basics. Red to red, black to black, blew to bits.

    Anyway I should have also said you could probably also stick a capacitor such that switching batteries with a little slide switch will not cause any interruptions. I am not sure what charge that holds but assuming it is a normal 3000mAh or so and you are getting 5-6 hours from it then you are not even going to need a supercap and can probably do with a basic electrolytic of reasonable capacity.
     
  14. xdarkmario
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    xdarkmario Philosopher

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    \cant just switch out fast, its soldiered wires, if i need to switch batteries i need to unsolider them. 1 battery charges fine. thing still being that the controller has no real support for rechargeable batteries so dont know if the battery is full or not, i just leave it charging overnight, the guy said that it takes "about" 4-6 hours to charge.
     
  15. Catastrophic

    Catastrophic Perfectly Normal

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    From what I've read, there are some concerns about connecting batteries in parallel, because if the voltage potential of one battery falls below the voltage of the other, the battery with the higher voltage will attempt to charge the one with the lower voltage, as they share the same common ground. However, many devices apply batteries in parallel, and it is taught that connecting batteries in parallel increases Ah rating. I'm supposing that as long as the batteries are of the same voltage and current ratings, you should be fine, as the batteries should discharge at the same pace. Not sure if this applies differently depending on the chemicals in the battery. Personally, I'd just get a bigger battery, but if you want to try looping two batteries, make sure to fully charge them both beforehand.
     
  16. mgrev

    mgrev Music Addict, Video Game Fanatic

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    kan komfrim my fredn and i blwe up en kar battry wonce
     
  17. Bimmel

    Bimmel ~ Game Soundtrack Collector ~

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    Ask somewhere else, or you'll explode.

    And I'm a electric engineer after all.
     
  18. FAST6191

    FAST6191 Techromancer

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    That top photo looks like a connector. If you can find another I guess that is a male connector to go on there then you can do things. Anyway when I said switches I meant like the following
    remote_demo_circ.jpg

    On the right is effectively what you have now, which is to say a battery and a load for it. Excuse the crudeness of that; I only had Fritzing here to play with.

    On the left is what I would propose you consider and dodge the charge management issues (or at least have them remain the same as whatever they were at the start of all this -- battery charging is more than just apply a voltage for a while which is what I fear this controller is doing now). The switch is there to allow you to select between batteries with a simple slide switch, the capacitor is an optional extra and will allow the controller to still work for the fraction of a second between swapping over via the switch.

    Depending upon what you want to do with even further batteries or finding male connectors then you might wish to go to a DPDT (double pole, double throw) but that is a trivial change.
     
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  19. Catastrophic

    Catastrophic Perfectly Normal

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    Pretty nice circuit. Having it like this would enable you to use batteries of different current ratings. :)