First look at TP5100


The TP5100 is the successor to the ubiquitous TP4056
It is slightly more expensive, but with some interesting features :

  • 4.2 or 8.4 (2S) battery charge
  • Buck converter instead of linear, dont heat much
  • Pin-out for external led display
  • No battery protection on the  board

Here is a pic of the small board you can easily find on eBay :



To switch to 2S mode, you have to join the 2 "SET" marks on the silk (bottom left).
It is a buck regulator, so in 1S mode you have to supply >= 4.5 v, in 2S mode >=9v.

By default, the chip is configured in 2A charging mode, which is a bit too much for my taste.
If we look at the datasheet (in Chinese), we can see that 2A = 0.05 ohm setup resistor.

That's consistent with the two 0.1 Ohm in parallel on the top left.

Let's remove one :


Now we are at 1A charging current according to the datasheet, and confirmed by my power supply.

On the right side of the board, you can see 3 holes. It is the pin-out for the external leds.

X Charged
X VCC (though 1K resistor)
X Charging


The Charging / Charged pins are pull down, they are lower than VCC when on, place for the cathode of a LED.
The led voltage does not seem to change wrt power supply.


The charging voltage is ~ 8.34 volt, so it will not overcharge slightly unbalanced 2S pack.



/!\ Big fat warning : If you use 2S,  you must use identical batteries, and  you must balance-charge them once in a while. 



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