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I have rigged up a small DHT11+ESP8266 combo which I'm currently powering from the 3.3v from an Ardruino. I've ordered a 3.7v LiPo battery and have a Adafruit usb micro LiPo charger, however, the battery will take two weeks to come.

Can I plug the usb charger directly into the DH11 while my battery arrives?

  • What kind of module is the ESP8266? Wemos? NodeMCU? AIThinker module only? Bare chip? – jose can u c Aug 31 '18 at 14:38
  • DHT11s use next to nothing, you can power it from a GPIO set to output HIGH... – dandavis Aug 31 '18 at 16:11
  • It's an ESP-01S. "DHT11s use next to nothing" I'm more worried that the charger will fry it. Is the voltage the only thing I should be worried about? – Retiarius Aug 31 '18 at 16:18
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No, you can't.

The charger circuit will only operate properly with a battery attached.

It is not designed to provide power to a system. It is designed for charging the battery and nothing else. You are supposed to remove the battery from the charger and then attach it to your circuit. Even with a battery attached you can't use it to power your circuit - the voltage will be too high, and your target circuit will confuse the charger and it will fail to charge the battery properly (or it may end up over-charging the battery).

To do what it sounds like you want to do you need:

  1. A LiPo charge circuit
  2. A 3.3V regulator (ideally a Buck/Boost combined regulator)
  3. Bypass circuitry to power the 3.3V regulator directly from the incoming power when present or from the battery when no external power is present.
  • ok, - what is the difference between the power supply coming from the charger and the supply after the steps you've mentioned here? I Don't want to use the two in conjunction - when I have the battery I'll just be using that, as you suggest. So it looks like the only difference is the 3.3V regulator - is the only concern that the charger will not give out a steady 3.3V voltage? – Retiarius Sep 1 '18 at 11:24
  • The charger press out special voltages and currents depending on the state of the battery connected. With no battery it won't know what to do. – Majenko Sep 1 '18 at 12:10

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