3s Li-Ion BMS

Discussion in 'The Projects Forum' started by mrblanco11, Mar 27, 2016.

  1. mrblanco11

    Thread Starter New Member

    Mar 1, 2016
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    I just bought a HH - P3-10.8 BMS to use on a 3s pack I'm making. I'm confused about the input and output. are they from the same place? I'm going to be charging it using a 5V power block and running that through a boost converter to 12v and need to break out power to 3 sources. 1 at 12v and the other two at 5v. Please help with a wiring diagram if possible. Thank you. s-l1000.jpg
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
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    Hmm, what? I am not entirely sure what you want to achieve. A BMS aka battery management is made so that it doesn't allow overcharge or overdischarge of the lithium batteries.
    That means you have three cells in the pack, and it gives you rougly 10.8V.
    You say you need 12V out, is 10.8 to 12.6 good enough, or do you need better control?
    You say you need 2x5V, do these two need to be not connected to each other in any way, or why do you need two separate sources?
     
  3. mrblanco11

    Thread Starter New Member

    Mar 1, 2016
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    I have 6 3.7v batteries. 3 in series and 2 packs of that in parallel so it should be around 11.1v which is a good enough voltage for the 12V source. The 2, 5V "outs" will be for 2 separate sources which I plan on going through 1 buck converter and splitting the output of that. What I don't know is how to wire up the BMS. From the diagram shown, I'm not entirely sure if the part that says "negative" and "positive" if that refers to the power coming in to charge the batteries or the power coming out of the batteries. Maybe it's me being a newb, but can I just wire the input source to that as well as the 3 breakout sources I just described?
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
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    I am not still sure what you want. Three batteries go into BMS. Out of there, you have somewhere around 12V. From those 12V you make 5V, most likely using a SMPS.
    Why or how would you want to put two 5V inputs into one buck converter I don't know, but it sounds not reasonable nor practical.
    Care to explain why you want it like that and how it is suppose to work?
     
  5. mrblanco11

    Thread Starter New Member

    Mar 1, 2016
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    I think we're just having some miscommunication.
    I'm making a 12v battery pack from 6, 3.7v Li-Ion batteries because i need to power a 12v amplifier. I also need to power a 5v bluetooth module and I'm also putting in a usb break-out to charge other 5v devices (phones, tablets, etc..). I'm using the BMS on the 12v battery pack I'm making. I've got a buck-down voltage converter in order to properly power the 5v devices. Additionally, I'd like to charge the batteries using a standard 5v, 2.4a power supply (from an iPad) with a usb cable. I've also got a boost converter to do this. How do I wire the entire thing?

    As a side note, I'd also like to be able to power the whole thing when the batteries are dead. I know this would require a bigger power supply. I have a 12v 75w power supply from a laptop I could use to power it, but again, don't know how to wire it. Thank you :)
     
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