Adding a balance tap to cheap welded battery pack- Mtbr.com
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  1. #1
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    Adding a balance tap to cheap welded battery pack

    Hi guys.

    I'm struggling to add a balance tap to my welded battery pack. I've got the black and red wires going to the main outputs of the pack, where the light usually connects, and the blue goes down to the bottom of the pack to what is labled B-
    As you can see on the cell checker, it's not picking up a voltage.
    If I proble the red + black and Red + Blue wires, i get voltage readings at the balance connector.
    Can anyone see if I've done something glaringly wrong? I know my soldering isn't the best, I was a little shaky doing this yesterday. I wanted to prove it worked then tidy it up.
    Adding a balance tap to cheap welded battery pack-battery1.jpgAdding a balance tap to cheap welded battery pack-battery2.jpg

  2. #2
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    I think you've got the blue wire connected incorrectly. Blue should go the the center tap of the 2S2P pack which is end where all 4 cells are connected together... in your photos looks to be on the right side of the battery pack where there will be a single lead going to the PCB.

    2nd photo here shows where the blue wire should go: SolarStorm X2 Battery Balanced? NO. 14/04/20 Update: Fixed | BudgetLightForum.com

  3. #3
    RAKC
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    Red and blue, then black and blue should read half the voltage of the pack when wired correctly. But it looks like you have protection leads going to each bank of cells on that set up which is utter failure on the pack maker. There should be a bridge linking all 4 cells together on the bottom of the pack or balance tap wont work. Where the blue wire is, the lead on the other side, all of that should be one lead normally.

    Post pictures of the bottom of the pack (opposite of the battery connector).

  4. #4
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    Here's the bottom of the pack
    Adding a balance tap to cheap welded battery pack-1-p1030453.jpg
    Here's the top.
    Adding a balance tap to cheap welded battery pack-1-p1030457.jpg

    Measuring voltage from the points labeled B+ B- and BM on the PCB I get the following readings
    BM to B+ = 3.47v
    BM to B- = 3.48v
    B- to B+ = 6.96v

  5. #5
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    Quote Originally Posted by kwarwick View Post
    I think you've got the blue wire connected incorrectly. Blue should go the the center tap of the 2S2P pack which is end where all 4 cells are connected together... in your photos looks to be on the right side of the battery pack where there will be a single lead going to the PCB.

    2nd photo here shows where the blue wire should go: SolarStorm X2 Battery Balanced? NO. 14/04/20 Update: Fixed | BudgetLightForum.com
    If I use my Multimeter and measure the following points on the PCB I get these values -

    BM to B+ = 3.47v
    BM to B- = 3.48v
    B+ to B- = 6.96v

    Measuring my wiring at the balance plug, I can see that I've gone wrong with the wiring.
    I thought it had to have two negative connections and a common positive. Ignoring the wiring coming out of the pack, am I best soldering direct to the battery tabs on the PCB?

  6. #6
    Drinkin' the 29er KoolAid
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    Quote Originally Posted by soopahfly View Post
    Here's the bottom of the pack
    Click image for larger version. 

Name:	1-P1030453.JPG 
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Size:	220.9 KB 
ID:	1035275
    Here's the top.
    Click image for larger version. 

Name:	1-P1030457.JPG 
Views:	91 
Size:	155.6 KB 
ID:	1035276

    Measuring voltage from the points labeled B+ B- and BM on the PCB I get the following readings
    BM to B+ = 3.47v
    BM to B- = 3.48v
    B- to B+ = 6.96v
    Pictures confirm what I thought... you have the blue wire going to the wrong place. BM (battery middle) shown in your second picture with all 4 cells tied together in a U pattern is where you want the blue wire connected. Red lead should go to B+ and black lead to B-.

  7. #7
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    Quote Originally Posted by kwarwick View Post
    Pictures confirm what I thought... you have the blue wire going to the wrong place. BM (battery middle) shown in your second picture with all 4 cells tied together in a U pattern is where you want the blue wire connected. Red lead should go to B+ and black lead to B-.
    I swapped the wire to the BM wire and it works a charm.
    Thanks for your help. I feel much better being able to bin the crap chargers that come with these.

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