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Charging / Battery Circuit, Trying to figure out if this will work

Discussion in 'Power Electronics' started by Platima, Aug 2, 2009.

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  1. Platima

    Platima

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    Aug 2, 2009
    Hey people,

    This may seem like a basic question to some of you, but im trying to get my head around this and i cant seem to figure out if its 100% OK. It looks good, but i may very well be wrong.

    What im trying to do is tie together these 3x 240VAC Li-ion battery chargers, and 3x 12VDC Li-ion batteries into one 240VAC IN -> Charge -> Supply -> 36VDC OUT kind of circuit (if that makes any sense. Haha).

    Linked in is a basic circuit diagram of my best guess at how to achieve this. If my explanation above made no sense hopefully the picture will clarify it.

    Thanks heaps in advance,
    -Keith
     

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    Last edited by a moderator: Aug 2, 2009
  2. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    Seems perfectly correct to me. Bike?
     
  3. Platima

    Platima

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    0
    Aug 2, 2009
    Yup, bike.

    Looks right to me too, but something in the back of my head is flashing warning bells. I guess its because the chargers end up being in an incomplete series circuit in parallel to the incomplete battery/cell series circuit.

    The other issue i've hit now though is i am also charging each cell individually instead of all at once, which looks to be getting complicated.

    Thanks for your feedback though
     
  4. neon

    neon

    1,325
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    Oct 21, 2006
    charging battery with ac that is a very bad idea expecialy li-ion battery they are sensitive to all kinds of enviroment and charging rates and so on. Even a acid battery will not charge with that arrengement. I SUGGEST do not ry.
     
  5. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    There's not an incomplete series anywhere afaik. & I don't see the need for individual charging. I'd go with the posted diagram.
    neon: you are interpreting the diagram too literally. Obvously Platima didn't have the correct symbols at hand so he just used transformer symbols instead, but you can get the idea anyway.
     
  6. Platima

    Platima

    3
    0
    Aug 2, 2009
    Thanks Resqueline you're right about the symbols (hence the transformer symbol being the wrong way around too). I just put that diagram together quickly using an online app as all my hand scribbled diagrams would be unintelligable to anyone else. Haha.

    I've had to reconfigure the cells and charging units because of the current limiters on the cells which i have removed. They were limited to 1A each but i know from the spec that they are capable of approx 6A continuous.

    The problem im having is that for charging, etc, i have every cell on a charging circuit, and every 3 charging circuits in series on a 12v 1A 240VAC adapter (represented by the transformers).

    I think i've just about got the whole thing sorted, but ill post some specs because i put it together, as i dont want to short Li-Ion cells.... I've seen these go up before.

    Thanks heaps for your advice too

    -Keith
     
  7. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    You're wise to be cautious..
    If the adapters are not originally intended for Li-Ion charging you might have a challenge, likewise if you (had to) remove the balancing circuit in each pack. Remember they don't like more than 4.2V each.
    Exchanging the current limiters (PTC fuses) for bigger should be ok but I wouldn't remove them altogether though, in case of a short. But you seem to know.
     
  8. AprilSteel

    AprilSteel

    111
    9
    Feb 2, 2017
    Don't know why you say that - OK on ac being bad for all batteries but li-ion is relatively hardy to charging and discharging so you will get less problems with them than L/A . Long as you keep within the High and low voltages limits and the battery charge amps regime.

    From what I see in the pdf the chargers are delivering DC anyway.?
     
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