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Battery Charging

!!password!!!!password!! Club Members Posts: 5
I'm trying to understand C's and the relation to charging and discharge.



I have 3s 25c 2200mAh batteries with a max charge current of 4c...

In my limited understanding, this means that it can discharge the 2200mA in 1/25th of an hour, and it those 2200mA can be max charged 1/4th of an hour.



I'm wondering what amperage a balance charge should be at. 2.2A? or less? and what amperage a fast charge could go to. 8.8A? 8.8A seems like a lot, so I'm not sure if my assumptions are right about C's.

Comments

  • WTWUKWTWUK CornwallClub Members Posts: 13,158 ✭✭✭
    The difference between Balance and Fast charging is basically Fast Charging does not balance the cells and may terminate charging at a slightly lower voltage than 4.20V. That saves time of course over Balance Charging. The amperage used is the same for both however. For your batter that would be ideally 2.2Amps, and I certainly would never even think of trying to ram 8.8A into a 2200mAh battery, no matter what the manufacturer says it can handle.
  • SawdustSawdust Club Members Posts: 6,763 ✭✭✭
    " this means that it can discharge the 2200mA in 1/25th of an hour, and it those 2200mA can be max charged 1/4th of an hour. "



    No. I think you've become confused by the fact that capacity is stated as milli amp hour "mah". That's just a way of explaining how much stored energy it holds. 2200mah means that over an hour period it could continually release 2200ma (2.2 amps) over an hour period before being completely empty. C represents capacity and when it says something like "25c 2200mAh" the "25c" means that it can (supposedly) safely discharge at 25 times that 2200mah capacity = 55 amps.

    And yes, stick to 1c (2.2amps in this case) for charging is what most of us would highly recommend, despite bragging figures put on by manufacturers.   
  • jstremmlerjstremmler Germany&U.S.A.Club Members Posts: 436
    Let's apply some maths:



    If I charge this lipo with 8.8 amps that means it would be fully charged in 15 minutes.



    (nobody would do that, because, if we like our batteries, we charge only with 1C = 2.2A = 1 hour in this particular case)



    And if I discharge this battery with 55A, then it would be completely discharged after 2.4 minutes



    (as we like our batteries we dont do that either...)
  • SawdustSawdust Club Members Posts: 6,763 ✭✭✭
    "And if I discharge this battery with 55A, then it would be completely discharged after 2.4 minutes



    (as we like our batteries we dont do that either...)"



    Agreed, but those figures do give us a rough guide to what C rating we need for a certain job. Always a higher C rating than we need of course, NEVER lower than we are likely to be pulling out of it.
  • sarahleesarahlee Club Members Posts: 1
    For your 3s 25c 2200mah battery, the 2200mah means that over an hour period it could continually release 2200ma (2.2 amps) over an hour period before being completely empty. C represents capacity and when it says something like "25c 2200mAh" the "25c" means that it can (supposedly) safely discharge at 25 times that 2200mah capacity = 55 amps. I agree with his words.you can learn more about it.
  • SawdustSawdust Club Members Posts: 6,763 ✭✭✭
    Thanks for the input sarah but that was all 4 months ago. Not to mention you basically just repeated what has already been said and I think made perfectly clear.
  • Rescue_RichRescue_Rich Club Members Posts: 17

    If it says Max charge rate 4c this means you can safely charge the battery at 4x the mAh.

    Example if you has a 3S 1500mAH you can set your charger to 6A 1500X4=6000mAH or 6A
    Me personally I wouldn't charge higher then 2 or 3 times the c rating the slower the charge the less heat the better for the battery.
    Do not confuse discharge with the charge rating this can be a disastrous error.

    Please familiarize yourself with all the ins and outs of LIPOS and charging.

    https://rogershobbycenter.com/lipoguide/
    http://www.tested.com/tech/502351-rc-battery-guide-basics-lithium-polymer-batteries/

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