NodeMCU don't auto start after battery drain

Hello guys,

I have a problem with my NodeMCU, don't auto start after battery drain. I have a solar panel powered a 18650 battery connected to NodeMCU.

When the battery is charged after a full drain, the NodeMCU don't auto start, I need to disconnect and re connect VIN pin to get working again.

Exists a solution for this problem ?


Schematic and picture of the device and circuit?

Other info would be wonderful as well.

Such as are you using one of those battery shields?

Sory for my primitive drawing.

I don't have a picture right now, because its on my roof (it's a weather station), but if it's needed I can take one.

Maybe it's useful to know. I use deep sleep on my code and have a cable between PIN D0 and RST.


I ran a weather station for 4 months under a similar configuration using an ESP32.

I tried 5V solar cells, at best I got 4.7 volts out of them. The TP4060 wants 5 to 8 volts for proper operation. I found a 5V solar cell would not work reliably without frequent LiPo removal, take inside, and charge every 5 or 6 days.

I switched to a 12V, 17V unloaded, 10 watt solar cell. I then ran the solar cell to a switching regulator to step the V down to the 6.

To properly power the MCU, I used a 3.3LDO to provide power from the TP4060 to the MCU, The LDO also served to stop the MCU from draining the battery when power fell below MCU operating voltage.

You may find that using a LiPo is NOT a hands off approach. You'll need to replace the LiPo about every 4 or 5 months. Also the LiPo cannot ever freeze, LiPo batteries contain water. If a LiPo freezes throw it away.

There is no good industry solution for LiPo and solar. The only good solutions are using lead acid or LiFePo4 batteries with either a MPPT or PWM charge controller.

Now I use a 30Watt solar cell connected to a 7Amp PWM controller that feeds into a 16Ah LiFePo4 which supplies a 5V 3A switching regulator. I currently have 2 ESP32's, 2 servo motors, and various sensors running on solar.

I went outside, recently, to clean the solar cells off, the ducks have become fond of using the solar panels (one 10 and one 20 watt) as a slide, otherwise its been a hands off setup.

Oh, the weather station, on LiPo, did deep sleep for 5 minutes. Now, with the LiFePo4, the weather station remains active 24/7 sending data every 17 seconds; no sleeping.

The solar powered project does not run off of solar cells, it runs off the battery.

During a typical day, my solar battery will reach a charged state, with the battery charger having higher capacity to provide current then the loads drain. The charge controller will stop charging the battery, cutting off power from the solar cells. When solar cell power is cut the battery supplies power to the circuit. When the controller detects the battery falling into the charge it range, the controller will provide power to charge the battery, replacing what has been used. As long as the charge controller detects a current supply, the solar cells, it will try to charge the battery when needed.

LiPo batteries contain water. If a LiPo freezes throw it away.

Lithium reacts irreversibly with water making LiOH and hydrogen, so lithium batteries never
contain water and have to be hermetically sealed from the environment.

At low temperatures LiPo basically stop functioning, most aren't rated below -10C for discharge,
or below 0C for charging. This is simply an activation energy effect. Its recommended to
not store them below about -10C.

LiFePO4 chemistry is much better at low temperatures BTW

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