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Building a Dual MOSFET Dual Parallel LiPo

Discussion in 'Unregulated (Mechanical) Mods' started by MarkS, Oct 6, 2017.

  1. MarkS

    MarkS Gold Contributor Member For 3 Years

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    My questions in doing this:
    Should I connect the balanced charging plug between the two LiPo cells to keep the cells cross balanced?
    If I do this would it potentially cause a problem (thinking about path of least resistance)?
    Should I put a small resistor in line with each line?


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  2. art247

    art247 Member For 3 Years

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    Hi i dont know the answer but im glad you are building more power to you

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  3. VapingGuitarist

    VapingGuitarist Silver Contributor Member For 1 Year Unlisted Vendor

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    Sounds like a cool build. As for your question, are you trying to use the balance leads to supply power to the mod? If so, don't do it! Your balance leads are for charging only and not for supplying power. If you're wanting to Y your balance leads for charging, I still wouldn't do it. You'd be much better off and safer to charge each pack seperately or on a multi pack balancing charger. I've been using all types of LiPo's for R/C aircraft and cars since they first came out in the hobby back around 2001 and haved worked in hobby shops long enough to see anything that can go wrong with LiPo's including venting and fire. Not fun!

    Shawn
     
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  4. MarkS

    MarkS Gold Contributor Member For 3 Years

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    I plan on using two packs in parallel. I was considering connecting the balanced charging connectors while in the Mod so the joined parallel LiPos would stay balanced with each other during the use cycle. I plan on charging them separately on my balanced charger. I’m thinking I may just put in two separate battery level meters to monitor both cells and not interconnect the packs.


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  5. VapingGuitarist

    VapingGuitarist Silver Contributor Member For 1 Year Unlisted Vendor

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    The balance leads are for charging Only!
    You're asking for trouble if you use them for supplying power!
     
  6. MarkS

    MarkS Gold Contributor Member For 3 Years

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    [​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG]


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  7. The Cromwell

    The Cromwell The Frugal Vapist VU Donator Diamond Contributor Member For 2 Years

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    You need a balanced charging circuit.
    Charging lipo cells in parallel is a very bad idea.
     
  8. MarkS

    MarkS Gold Contributor Member For 3 Years

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    That's why you see two balanced charging plugs. I use an external charger.


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  9. MarkS

    MarkS Gold Contributor Member For 3 Years

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    Well... I decided to add the option of being PWM also. Now... to get it all to fit!
    Phoenix Wiring Dual Mode.jpg
     
    Last edited: Nov 3, 2017
  10. MarkS

    MarkS Gold Contributor Member For 3 Years

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    Putting up a revised drawing. I ran out of room to put everything in the Mod that I wanted. So, I've gone to a three wire LED VM to act as a pilot (Mod on) light reading 0.00, provide a relative voltage (for adjusting) in PWM mode, and actual voltage in unregulated mode when the fire button is pushed. The pilot LED or the LED VM had to be removed from play. Obvious selection for me... bye bye pilot (on indicator) LED. Phoenix Wiring Dual Mode R2.jpg
     
    Last edited: Nov 10, 2017
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  11. KingPin!

    KingPin! In my defence, I was left unsupervised ^^ Staff Member Senior Moderator VU Donator Platinum Contributor Member For 1 Year VU Challenge Team Reviewer

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    Nice project MarkS thanks for sharing :cheers:
     
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  12. MarkS

    MarkS Gold Contributor Member For 3 Years

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    Progress update. It’s a little rough since I don’t have all the cool tools to do this on a normal basis.
    [​IMG][​IMG]


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  13. MarkS

    MarkS Gold Contributor Member For 3 Years

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    Finally finished except the cleaning. Had to replace multiple parts multiple times but finally working as it should. Barely able to fit everything into the housing.
    [​IMG][​IMG][​IMG]


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  14. MarkS

    MarkS Gold Contributor Member For 3 Years

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    Well... Here's the latest Pics:[​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG][​IMG]


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  15. MarkS

    MarkS Gold Contributor Member For 3 Years

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    Lessons Learned:
    1) Always test components individually after soldering (from original fire switch failure)
    2) Calibtate the LED DVM before installation (self explanatory)
    3) Don't flex Potentiometer leads, they break easily (self explanatory)
    4) Use the right tool for the job (center punch - couldn't find and freehand drilled holes, wrong Dremel cutting wheel for meter opening, and drill bit just one size too small for replacement button)
    5) Always me mindful to protecting the finish on the Mid Box (protective tape, towel, paper towels, or multiple things to keep from scratching finish)
    6) Laser engraving/etching should be the last thing done, not the first (related to #5 anbe)
    7) Don't use heaver gauge (oversized) wire just because you think bigger is better (it takes up space!)
    8) Case size does matter, allow extra!


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