I have this weird issue. I'm currently hooking up a 6-pack of 18650 batteries in parallel. I'm currently hitting 3.8v using the whole pack at the connector (yes, I need to charge them up). If I hook up my 5 meters of LED strip to it, I get a voltage drop in the beginning, which is really weird! Here's how I've hooked it up:

The VIN on the ESP8266 board can receive a wide range of voltage, so it doesn't matter if it gets 3.3v or 5v. The batteries won't ever go below 3.5v, so I don't need to worry about that.

The VIN pin receives about 1.3v whereas the first LED receives the 3.8v. The terminal/connector that splits the cables is simply one of these connectors. So the battery pack has a male connector, that connects to the female, which simply has two cables running from it.

What on earth is wrong?

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    \$\begingroup\$ Mixed up the blue wire with the black one? What if you disconnect the LEDS? \$\endgroup\$
    – Eugene Sh.
    Commented Nov 23, 2017 at 17:51
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    \$\begingroup\$ What if you remove the blue wire? \$\endgroup\$
    – Eugene Sh.
    Commented Nov 23, 2017 at 18:00
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    \$\begingroup\$ Can you put the red wire to the ESP directly to the battery? Do the same with the black wire (one at a time) and see if that helps. \$\endgroup\$
    – Ron Beyer
    Commented Nov 23, 2017 at 18:02
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    \$\begingroup\$ Are the wires thick enough to handle the current? \$\endgroup\$
    – bobflux
    Commented Nov 23, 2017 at 18:05
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    \$\begingroup\$ Can you post a photo of the contraption? \$\endgroup\$
    – bobflux
    Commented Nov 23, 2017 at 18:11

1 Answer 1


Turns out it was a bad wire. I resoldered the original one probably 5 times total, but decided to grab a new wire and then it worked perfectly.

As peufeu said in one of the comments: This is one of these voodoo failures

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    \$\begingroup\$ Actually it's one of those... "If I tried all the possible problems and found nothing, then I need to check the impossible problems." problems. \$\endgroup\$
    – Trevor_G
    Commented Nov 23, 2017 at 19:11
  • \$\begingroup\$ @Trevor Haha that's true! \$\endgroup\$ Commented Nov 23, 2017 at 20:10
  • \$\begingroup\$ Ha this happens to me always ! \$\endgroup\$
    – Mitu Raj
    Commented Nov 23, 2017 at 20:22

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