I need to replace two LED diodes on a TP4056 board (bottom right corner on the picture).

Enter image description here

The board is going to be in a box and I want to move diodes to the small holes in the box.

There are two resistors with marks 102, and that is 1 kilohm. I measured voltage on diodes and my multi-meter said 2.7 V.

I want to use something like this:

Enter image description here

Those diodes are 3 V 20 mAh. Can they replace exiting diodes?


Thank you guys. You helped me a lot.

Btw, current LEDs are blue and red

  • \$\begingroup\$ Welcome to EE.SE. For this question to be any use to future readers it is important that you include the images inline in your question so that it still makes sense when the eBay links die. Not many of us will follow links just to understand what you are asking about. There should be enough information in the question to answer it. The current rating of diodes will be in mA, not mAh which is used as a measure of energy capacity in a battery. There is an edit link below your question ... \$\endgroup\$ – Transistor Jan 11 '19 at 19:04
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    \$\begingroup\$ An alternate solution is that you could use a light pipe to guide the light from the existing LEDs to the place you want to see it. On some devices the plastic thing you see lighting up is not the LED itself but one end of a light pipe. \$\endgroup\$ – Dithermaster Jan 12 '19 at 16:16
  • \$\begingroup\$ FYI: "LED diodes" stand for "light-emitting diode diodes". Just use "LEDs" instead. Sorry for being a nudnik. \$\endgroup\$ – CYB3R Jan 12 '19 at 17:29

enter image description here

Figure 1. Typical IV curves for various colours of LEDs. Image source: LEDnique.

Replacement of any of those small indicator LEDs with 3 or 5 mm LEDs should be fine.

A little bit of background theory may help. LEDs have a non-linear relationship between applied voltage and current. The forward voltage also depends on the colour as shown in Figure 1.

Your measured 3 V LED voltage suggests that you've got either white or blue LEDs on the board. With the 1 kΩ resistor in series the current will be limited to a safe value even if you change to one with a lower forward voltage.

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Based on the schematic in the datasheet, they're not critical, any LED will do. enter image description here

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  • \$\begingroup\$ Also, when designing something like this it is very common that the manufacturer just implemented the reference design, so chances are high that you will find a red and green (greed?) LED just like shown here. \$\endgroup\$ – pipe Jan 12 '19 at 9:21
  • \$\begingroup\$ These boards often follow the reference design exactly - all the versions I've found or sale have the same color LEDs for indication. There's also an over- and undercharge battery protection circuit on this board - the two packages in the left side, that looks like it's the one here - electronics.stackexchange.com/questions/203463/…. \$\endgroup\$ – Phil G Jan 14 '19 at 14:57

Yes, you can most likely replace the SMD LEDs by any "jellybean" LED. You can easily try it. Do observe the correct LED polarity.

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  • \$\begingroup\$ Even getting the polarity wrong is unlikely to hurt anything, it'll just result in the LED not lighting, while the rest of the circuit works normally. And the LED won't be harmed either, so once installed with the correct polarity, it'll be just fine. \$\endgroup\$ – Ben Voigt Jan 11 '19 at 23:02
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    \$\begingroup\$ Correct. But the LED won't work, that's all I was saying. \$\endgroup\$ – Wouter van Ooijen Jan 12 '19 at 9:09

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