Battery Protection Module

Discussion in 'Voltage' started by Space Puppy, Nov 1, 2017.

  1. I bought this four pack of these li-ion batteries (NCR18650B 3.7 Volt 18650 3400 mAh)

    I plan on using the batteries in a 2s2p configuration. This should deliver 7.4V 6800mA.
    Will this protection module work for the configuration I plan on using it for? I believe it should handle 6.8A as the over current protection is rated for 11A (+/- 3A).

    Any help is greatly appreciated!
  2. GingerOfOz

    GingerOfOz Member

    Yep, that PCB should work fine for protecting your batteries. One thing to note though, is that it doesn't have battery balancing circuitry, unless I overlooked something. With a 2s2p configuration like that, you should e perfectly fine without one so long as you always charge and discharge the batteries together, and don't do anything stupid.

    Good luck!
  3. Great, thank you! I have a 8.4V 1.2A charger that should work with this set up.

    On another note, does this circuit turn off the batteries from use while charging and still output power? Im assuming that I should make a separate charging and wall power jacks for when I would want to charge and use the device at the same time. I am trying to get away from this configuration and was wondering if there is some kind of switching system that could be implemented.
  4. GingerOfOz

    GingerOfOz Member

    What are you building a battery pack for?

    There are boards that allow you to have charge and play through a single port, check out this thread. There is a lot of information, but it's all really, really good. The other issue you're going to run into, is the fact that we haven't found a board like these that does a 2s2p configuration like you're using. Depending on what you need, the 4s pack may or may not work. These boards are also somewhat pricey, and be sure to make sure the boards have protection circuitry on them, or be sure to buy a PCB separately.

    Additionally, these boards don't use smart chargers, they use standard power supplies.

    Hope this helps.
  5. I plan on using this for a portable N64.

    I see the issue you are describing, the configuration I am using provides more current than the 2s charge management boards can handle. I might make my own charge manager using a P MOSFET and diode, seeing as how there is a simple circuit shown in the link you provided.

    I could also use a switching power jack that breaks the connection from the battery and a diode to direct flow from the power jack back into the battery. I would imagine that this would work so long as the diode drop is taken into account. Is there a reason I have not seen a solution such as this implemented?

    I notice the charger I have planned to use is a smart charger so I wont be able to use it. Id imagine there are plenty of normal power supplies rated for 8.4V and 1.2A, however I would imagine that a single charge and play port will require close to 2A, possibly more depending on current draw of the system.
    Last edited: Nov 1, 2017

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