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Powerbanks

  • gasbag11 Top 10 Forum Poster Tuesday, October 16, 2018 5:30 AM Reply

    I'll admit that I know less about electronics than I do about computers, (which is just about 0) but I'm wondering if I charge an amost dead 3000mAh cell with a fully charged cell of equal capacity in a powerbank, will charging stop when both cells are equally charged? Sorta like a hose connecting 2 (equal volume, equal height, etc) containers of water? 


    Or is there something in the powerbank electroncs that would keep charging the other cell?


    @sheepish

    @desolder

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  • sheepish Top 10 Forum Poster Tuesday, October 16, 2018 6:04 PM Reply

    Are you talking about putting two cells of very different states of charge in parallel with each other in the same power bank? Don't do it. The current could be very high, which would be bad if the cells are not protected.


    I had a post years ago where I explained the greater the difference in voltage the higher the current. It's basically limited only by the internal resistance of the cells, which leads to the voltage of the discharging cell to drop under load, and the voltage of the charging cell to increase while being charged.

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  • gasbag11 Top 10 Forum Poster Wednesday, October 17, 2018 4:22 AM Reply

    No. 


    What I meant was charging a device with an almost dead battery, with a powerbank that has roughly the same capacity.


    Would the charging stop when both batteries are about equal in capacity, or could the powerbank keep charging the device until it has more capacity than the powerbank? (Naturally the device would not be used while charging)

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  • sheepish Top 10 Forum Poster Wednesday, October 17, 2018 4:56 AM Reply

    That'll be fine. The powerbank boosts the ~3.6 V of its battery up to 5 V for the USB output, so it'll keep going until the powerbank is flat and/or the device is fully charged. Surely you've charged a cellphone from a powerbank?


    Some power (and thus energy) is lost with the voltage conversion, so if the batteries have the same voltage and capacity don't expect the powerbank to fully charge the device.

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  • matrix-neo Moderator Wednesday, October 17, 2018 6:07 AM Reply

    the 2 containers of water analogy doesn't take into account the powerbank, at first gb i thought you meant taking 2 bare cells and connecting them together which sheepish said isn't a good idea, not to mention bad things like cell reversal, also in the analogy how do you simulate internal resistance/impedance?

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  • gasbag11 Top 10 Forum Poster Wednesday, October 17, 2018 8:16 AM Reply

    Surely you've charged a cellphone from a powerbank?


    Lol... I don't have/never had one. Yep! I'm THAT old. 


    6 ~ 7 years ago my wife's phone went off while she was driving. She handed it to me to answer and I proceeded to screw it up instantly. After we got home she had to call my son to figure out how to un-screw it up. She's never let me touch one since. 


    Neither has my son. Or daughter. :)

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  • sheepish Top 10 Forum Poster Wednesday, October 17, 2018 8:21 AM Reply

    6 ~ 7 years ago my wife's phone went off while she was driving. She
    handed it to me to answer and I proceeded to screw it up instantly.
    After we got home she had to call my son to figure out how to un-screw
    it up. She's never let me touch one since. 


    Neither has my son. Or daughter. :)


    Wow. That's legendary. Why does she (your wife) trust you with a soldering iron?

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    post edited by sheepish on 10/17/2018 at 8:21 AM
  • gasbag11 Top 10 Forum Poster Wednesday, October 17, 2018 10:02 PM Reply

    Why does she (your wife) trust you with a soldering iron?


    It's most likely because there are no switches, buttons or controls of any sort for me to screw up. Plus I'm sure she figured after the first few times I have go to the emergency room because I've burnt a hole in one body part or another, I'd give up this stupid new hobby. 


    I never burnt myself, but I gave it up anyway. After you replace 8~10 LEDs and/or drivers, it gets repetitive and boring. Plus I met my goal of creating a really good thrower. sku.121721 with a better driver and an XP-L HI LED. In fact, it's such a good thrower that it's just about useless. lol (Actually it's a better thrower than my Manker U21 which is a dedicated thrower and has a supposed beam range  of 750m) The Manker is quite a bit brighter though, so it still might out-throw the Trustfire.

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  • sheepish Top 10 Forum Poster Thursday, October 18, 2018 4:13 AM Reply

    After you replace 8~10 LEDs and/or drivers, it gets repetitive and boring.


    If that's what you've done I'm really impressed.


    I can't find sku.121721. Is it gone as part of the site update or was it gone anyway?

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  • gasbag11 Top 10 Forum Poster Thursday, October 18, 2018 5:22 AM Reply

    I don't know how long it's been gone, but if you go to page 5 of my reviews, it's the one titled "Fantastic". (a Trustfire 168A) It was already a good thrower because of the deep reflector, but the new LED (which is domeless) made it even better... if you like throwers that is. 


    I upgraded the driver from (if I remember correctly) about 1.7A to about 2.5A. I would have gone a little more,  but the driver is in the battery tube and I don't think there's enough heat sinking if it was used on high for very long. 


    edit - I should have said the "pill" is in the batt.tube, not just the driver. lol

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    post edited by gasbag11 on 10/18/2018 at 5:38 AM
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