I am a total noob in electronics, and so some other answers to this question are already over my head. I am working off the inspiration of this design of an LED hoop: https://philihp.com/blog/2011/diy-led-hula-hoop/, but I don't understand the wiring diagram at the bottom of the page:

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I am wiring through hole 5mm LEDs + resistors to 22 gauge stereo wire in parallel, with the batteries interspersed in parallel. I don't want to make a battery pack, since this is a hula hoop I want to space the batteries evenly in the LED string inside the tubing, otherwise the hoop is off-balance and hard to use. In fact I already made a hoop with one battery and that experience made me want a design with balanced weight.

My focus right now is understanding how to have a built-in USB charger so that the batteries can stay in the hoop and be charged, and therefore be spaced evenly inside the polypro tubing to balance the hoop's weight. But it seems like I'm setting myself up to light myself on fire.

  1. This page at Adafruit says it's not safe to be a hobbyist and string/charge batteries in parallel, is that true? What if on each battery I put a Protection Circuit?
  2. Does each battery need a Protection Circuit?
  3. Adafruit says to only use its MICRO LIPO - USB LIION/LIPOLY CHARGER with their battery packs, which won't fit inside a hoop. Is there a different small charger I should/could use, like the one in this post?
  4. If I have 3 batteries does that change the charger I can use (voltage, current?) or will it just charge more slowly as long as it's rated for 3.7V batteries?

Sorry if a lot of this is obvious, I'm having trouble piecing the information together.

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    \$\begingroup\$ Have you though of using dummy weights instead of spacing the batteries apart? \$\endgroup\$ – Passerby Dec 26 '17 at 23:07
  • \$\begingroup\$ Exactly which batteries are you intending to use? How will you switch the circuit on and off? \$\endgroup\$ – Bruce Abbott Dec 27 '17 at 1:25
  • \$\begingroup\$ @Passerby I will think on this, but I'd prefer to not use dummy weights since the more stuff I put in the hoop the heavier it is, which from a performance perspective means slower tricks. The batteries acting as weights kills two birds, since I DO want more batteries for longer hoop life \$\endgroup\$ – sclarky Dec 28 '17 at 0:18
  • \$\begingroup\$ @BruceAbbott I will be using 3.7V 14500 Li-Ion batteries, see rtdvapor.com/aw-protected-14500 except hopefully finding some with tabs for soldering \$\endgroup\$ – sclarky Dec 28 '17 at 0:19
  • \$\begingroup\$ So the question is how much wire and what gauge is safe to spread the batteries around. I would be interested to know that too. What is the voltage and current draw you are expecting? \$\endgroup\$ – Passerby Dec 28 '17 at 0:21

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