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Using a 3S LiPo

    • 11 posts
    June 9, 2021 3:27 AM CEST
    Emi Grago said:

    "None of the answers is really helpfull, id rather have a detailed instruction on how to create a safe 3s LiPo Batterybox to be used with an SBrick."

    AHAHA.
    None of the answers is really helpfull I'd rather have someone tell me where to get a 1967 corvette stingray in mint condition and drive me there and pay it for me and fill it with fuel!!!
    Dude, YES, the answers are helpfull! What you want is someone to breastfeed it to you.
    Not gonna happen! This is DIY country, so get your hands dirty like everyone else! LEGO is for makers not for puzzle-layers.
    ...it used to be before those stupid bricky mouse mosaiks anyway - sigh.

     

    • 11 posts
    June 9, 2021 3:16 AM CEST

    counter: use a 4-cell LIPO!

    I use a 3cell lipo. The max charge is 12.6 V so I use a step-down-converter* to restrict the voltage to 11.8V
    (* aka buck-converter, tiny chip, to restrict the max voltage)
    works fine BUT the step down takes some of the voltage so 11.1V (LIPO voltage most of the time) becomes effectively 10.8 V
    therefore, either leave away the step down and risk going over the sbricks savety limets when fully charged but have only 11.1 V most of the time, or:

    My Recomedation:
    Use a 4-cell LIPO
    add a step down converter (1$ china)
    add a LIPO discharge alarm or discharge restrictor** (3$ china)
    and you should be able to get your fiery 11.8V out of it ALL the way until battery is depleted.

    **HINT: The usual do-not-discharge-below-or-you-kill-your-LIPO-threshold of a 4 cell lipo is 13.2 - 12.0 V depending on the brand. Since your step down is running below that you will not realize, your LIPO is going to die for good if you use the sbrick to check the charge. So get a LIPO discharge alarm or something that cuts the power if it goes below 13.2 V

    Question:
    what does the percentage of the sbrick battery widget refer to?
    is 100% = 11.8V?

    • 6 posts
    October 30, 2017 7:21 PM CET

    None of the answers is really helpfull, id rather have a detailed instruction on how to create a safe 3s LiPo Batterybox to be used with an SBrick.

    • 1 posts
    October 24, 2017 12:47 PM CEST

    Consider using a LiFePO4 battery as stated above.

    A 3S LiFePO4 battery will always be below the max safe working voltage when fully charged. (Max voltage for a 3S LiFePO4 battery will be 10.8v when fully charged)

     

    LiFePO4 batteries are also more durable in regards to safety etc as compared to a normal LiPo battery.

    • 1 posts
    October 21, 2017 9:39 AM CEST

    Hello, I have been running my S-Brick models with 3S LiFePo4 batteries, they are nominal 9.9V, I have just charged one and it is reading 10.2V.

    Alternatively you could probably look at a low drop out switchmode regulator to ensure the correct voltage is applied.

    I have put together some photos of making the adapter cables for onverting my batteries to Lego PF for my LUG, which I could possibly share if you are interested.

    Roland

    • 37 posts
    October 21, 2017 7:41 AM CEST

    Two solutions:

    1. I use a 3S LIPO Milwaukee 12 V battery connected to a adjustable DC power Supply set to 11 volts.

    2. I use a regular AA battery pack with 5 NIMH batteries and one LIPO battery.

    Both work well, but I'm using them in a high power battle robot application, and the thermal limiting circuitry on the SBrick soon derates the power and ends the fun.  SBRICK needs better power handling.

    • 6 posts
    October 20, 2017 1:30 PM CEST

    I am having the exact same question and this was discussed here and in other Forums serval times, i would really love to have some instructions that i can use to build my own 3S LiPo that is safe to use with SBrick+!!!

    Cant you SBrick Devs publish some legally nonbinding instruction suggestions for us?


    This post was edited by Emi Grago at October 20, 2017 1:30 PM CEST
    • 1 posts
    September 17, 2017 2:07 PM CEST

    Hey gang.  SBrick max voltage spec says 11.8V.  This would be ideal for a 3S Lipo (11.1V) with the exception that cells typically run > 12V fully charged.  Anyone come up with a way to use a 3S by limiting the max voltage when charged?  I know I could throw some sort of regulator on there, but don't what to throw it away as heat and inefficiency, and it's not needed when the cells fall to acceptable voltage (~11.1V).  I suppose Is there a such a thing as a switching regulator circuit that works when the voltage is above say ~11.5V and then auto bypasses when it goes below that? Or is that wishful thinking?