Simple TP5100 based charger


Using a TP5100, let's do a 2S battery charger.

The requirements are :

  • Usb powered, so ~ 10 W max with a 2.1A charger
  • Using cheap ebay voltage boost converter, ~ 10 W max too


That's why limiting the charge current to 1A is important.
With the default 2A charging current, we would exceed both the Usb charger and the boost converter specs.

What's needed  :



It is so simple, no need for schematics.

The end result :


As usual, crap design & workmanship.

Important :
It is much better to wire external leds rather than using the built-in dual led.
When nothing is connected, the "Charge done" led is on, the "Charging" led is blinking very quickly.
It is hard to see on the default very small dual led.



Update 1:

It was working fine with mostly charged batteries, but not that much with discharged batteries.
The DC/DC converter was getting really hot, and the input voltage was dropping to 3v

Update 2 :

After investigating, the TP5100 melt down, not so great so far....
Let's try with the 2nd one, it pulls 1A exactly.

Update 3:

The problem seems to be the DC/DC converter. Its efficiency is WAY too low for that setup
and the output is erratic.

Update 4: 

Finally the problem is the usb connection.
It cannot handle large current, tried with both micro and regular size usb.
Back to square one.


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