No wakeup after complete discharge of the batteries

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spicer
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No wakeup after complete discharge of the batteries

#1 Post by spicer » 03 Sep 2019, 18:58

German:
Hallo Gemeinde
Warum bootet der ESP8266 nicht, nachdem die Akkus komplett entladen waren und die Solarpanels wieder Strom liefern?
Ich denke, das dies wegen dem langsamen Spannungsanstieg ist.
Gibt es einen Trick (wie ein R-C Glied), um das hinzukriegen?


Translator:
Hello community
Why does the ESP8266 not boot after the batteries have been completely discharged and the solar panels are supplying power again?
I think that's because of the slow increase in voltage.
Is there a trick (like an R-C link) to do that?

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Re: No wakeup after complete discharge of the batteries

#2 Post by grovkillen » 03 Sep 2019, 19:10

Perhaps using a voltage regulator in-between?
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Re: No wakeup after complete discharge of the batteries

#3 Post by spicer » 03 Sep 2019, 19:14

Yes. I use a step down converter (7-12V to 3.3V).

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Re: No wakeup after complete discharge of the batteries

#4 Post by grovkillen » 03 Sep 2019, 19:34

Aren't you powering it with 5V?
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Re: No wakeup after complete discharge of the batteries

#5 Post by ThomasB » 03 Sep 2019, 19:35

One way to solve this is to use a brown out detector. This provides a reset after the voltage becomes valid. Same concept as the Power Good ("PWR_OK") signal on a ATX PC power supply.
For example: http://www.hnilica.cz/radek/zim/Electro ... cuits.html

- Thomas

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Re: No wakeup after complete discharge of the batteries

#6 Post by spicer » 03 Sep 2019, 19:36

No. 3.3V.
5V is very bad for the ESP :D

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Re: No wakeup after complete discharge of the batteries

#7 Post by grovkillen » 03 Sep 2019, 19:37

So what board are you using since you don't have a 5V VIN?
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ESP Easy Webdumper [easy screendumping of your units]
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Re: No wakeup after complete discharge of the batteries

#8 Post by spicer » 03 Sep 2019, 19:44

ATM i use a nodeMCU and give power over 3V pin. Vin is not connected. I know, is not a clean solution :)
Later i will use a "naked" ESP-12F modul.

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Re: No wakeup after complete discharge of the batteries

#9 Post by spicer » 03 Sep 2019, 19:47

ThomasB wrote: 03 Sep 2019, 19:35 One way to solve this is to use a brown out detector. This provides a reset after the voltage becomes valid. Same concept as the Power Good ("PWR_OK") signal on a ATX PC power supply.
For example: http://www.hnilica.cz/radek/zim/Electro ... cuits.html

- Thomas
Yes. This is a possible solution. With the TCM809 easy :)

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Re: No wakeup after complete discharge of the batteries

#10 Post by TD-er » 03 Sep 2019, 21:15

Maybe the ESP is trying to boot and thus discharging the battery more than the panels can charge it.
The EN pin on the ESP must be pulled high to boot the ESP.
Maybe you can make a simple trigger to only pull it high above some level to give the panels opportunity to get the batteries charged again.
It could also help to prevent discharge below some level.

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Re: No wakeup after complete discharge of the batteries

#11 Post by spicer » 03 Sep 2019, 21:30

Good idea.
I still have unused OpAmps.
This allows me to build a Schmitt trigger for the EN.

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Re: No wakeup after complete discharge of the batteries

#12 Post by ThomasB » 03 Sep 2019, 23:00

I still have unused OpAmps.This allows me to build a Schmitt trigger for the EN.
Don't forget that this application will require a micropower OpAmp; Single supply, rail-to-rail, and capable of operating at very low voltage.

- Thomas

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Re: No wakeup after complete discharge of the batteries

#13 Post by spicer » 03 Sep 2019, 23:06

Is a LMC6482.
But i think, i solve this with ThomasB's "brown out detector".

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Re: No wakeup after complete discharge of the batteries

#14 Post by spicer » 05 Sep 2019, 19:44

I build a circuit.
If the voltage (Ubat) is to low (adjustable with R4) the EN is L.
V1 (3.3V) is after the step down converter.
It works ^^ Thx TD-er
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Re: No wakeup after complete discharge of the batteries

#15 Post by TD-er » 05 Sep 2019, 19:52

Maybe you also want to add some hysteresis, or else it would not be able to charge the batteries again and keeps rebooting if the current needed for booting is pulling the voltage just below your set threshold.

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Re: No wakeup after complete discharge of the batteries

#16 Post by spicer » 05 Sep 2019, 20:01

That's what I thought about first.
But if the power is insufficient when booting, the EN is immediately set to L again.
A "flickering" would of course be possible and not desirable.

When I apply a resistor from out to +, I have a hysteresis (non-inverting Schmitt-trigger).
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Re: No wakeup after complete discharge of the batteries

#17 Post by TD-er » 05 Sep 2019, 23:34

Maybe also place some small capacitor parallel to R4 and one over V1.

I can imagine the DC/DC converter and the charging circuit may not give the most clean signal.
So by adding a small capacitor over them, you will eliminate most of the spikes introduced by those converters.
In order to simulate, you may need to add a 50 kHz (or more?) signal on top of your sine wave with an amplitude of 50 mV (?)

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Re: No wakeup after complete discharge of the batteries

#18 Post by Wiki » 06 Sep 2019, 13:50

It would be helpful to get an idea about your power supply scheme. Do you use a protection board for liion batteries?

If yes, have a look at its datasheet. Most protection boards are starting the charging cycle after shutdown of the power supply caused by low voltage of the battery with very low current. So switching the ESP on too early means that you won't get the battery alive again. You will have to charge the battery at least up to 3.2-3.3V before switching the ESP on to get the circuit alive.

This is the reason why power banks in most cases don't deliver power while being charged.

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Re: No wakeup after complete discharge of the batteries

#19 Post by spicer » 06 Sep 2019, 15:40

I use two (serial) Panasonic 18650 NCR18650B Li-ion battery 3.7V with protection PCB 3400mAh.
Simple way :D

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Re: No wakeup after complete discharge of the batteries

#20 Post by Drum » 20 Oct 2019, 05:14

Something like this might be easier. Reading the thread reminded me it is on my to do list. I currently use a simple one which shuts down the voltage regulator when the battery voltage gets too low. Originally I set it to shut down the voltage regulator when the vr output was too low... :o

https://www.onsemi.com/products/power-m ... ors/ncp304

From testing
At 2.2v esp restarts
At 2.1v shutdown
From 2.1 to about1.5v esp will restart with voltage increase
1.5v or below esp requires complete power off to reset

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Re: No wakeup after complete discharge of the batteries

#21 Post by pino_otto » 09 Jan 2022, 05:54

I have the same problem: wemos d1 mini (esp8266) does not wakeup after complete discharge of the battery.

The battery (18650) is charged by a solar panel with a TP4056 module that is connected to a 3.7v to 5v dc-dc boost converter, that is connected to the 5v input of the wemos d1 mini.
After the battery is discharged at night, the sun in the morning is charging it. Even when the battery voltage goes higher than 3.7v, the boost converter is not providing 5v at its output. The output (connected to the wemos input) stays at 0.8v.

I read from Drum message that "1.5v or below esp requires complete power off to reset".

How can I implement a circuit that gives the wemos a complete power off/on?

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Re: No wakeup after complete discharge of the batteries

#22 Post by TD-er » 09 Jan 2022, 12:20

You can use a FET to switch the power of the ESP.
This may also help protect your batteries, as it reduces the current drawn from the almost empty batteries.
Especially Li-ion batteries should never be discharged below some voltage or they will be permanently damaged.

Since the DC/DC converter also uses some quiescent current, you may even put the FET in front of the DC/DC converter.
A relatively simple schematic is this one: https://electronics.stackexchange.com/a/4969
Here some theory to apply a hysteresis too: https://www.analog.com/en/analog-dialog ... ckout.html

A hysteresis can be useful to give the battery some time to recover and get charged.
By turning off the load, the voltage on the battery may rise and thus turn on again, causing the FET to open again starting the DC/DC and the ESP again.

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Re: No wakeup after complete discharge of the batteries

#23 Post by pino_otto » 09 Jan 2022, 14:29

Thank you, TD-er.

Before using your suggestion (a FET to switch the power of the ESP), I would like to know if the following idea makes sense.

I am thinking to use a NCP304LSQ33T1G (3.3v voltage detector) to monitor the battery voltage. The output of this voltage detector will be connected to the "enable" pin of the DC/DC converter. When the battery voltage is lower than 3.3v, the DC/DC converter will be disabled and so ESP is switched OFF. When the battery voltage is higher than 3.3v, the DC/DC converter will be enabled and so ESP is switched ON.

Voltage detector: https://www.onsemi.com/pdf/datasheet/ncp304-d.pdf
DC/DC converter: https://www.aliexpress.com/item/32963598972.html

Do you think that this idea can work in practice?

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Re: No wakeup after complete discharge of the batteries

#24 Post by chemmex » 09 Jan 2022, 14:45

There's a battery monitor IC from chinese Consonance Electronics called CN302. It can be used to cut off the load (or shut down the ESP if connected to the EN pin) when the battery voltage drops down to the limit set by resistor divider. It also provides adjustable hysteresis to allow the battery be charged above the "gray zone" so that it can start up the ESP reliably.

It comes in SOT23-6 package and is quite cheap.

http://www.consonance-elec.com/pdf/data ... -CN302.pdf

https://www.aliexpress.com/item/1005002 ... 6e1eEgWkeE

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Re: No wakeup after complete discharge of the batteries

#25 Post by TD-er » 09 Jan 2022, 15:30

Both ideas are quite feasible.
It is rather important to have some kind of hysteresis in the switching to prevent constantly turning off/on.
Using the enable pin on the DC/DC converter is actually a very good idea to use, as it may be easier on the rest of the circuit as you will have a more soft start.

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Re: No wakeup after complete discharge of the batteries

#26 Post by chemmex » 09 Jan 2022, 15:54

NCP304 has just 0.1V hysteresis, that's too little, I would prefer to have ~0.3V at the lower end of LiPo discharge curve.

For DC/DC converter I would recommend this one https://www.aliexpress.com/item/1005002 ... 5f06bXMy9z
I's just a bit more expensive but is more efficient and capable of up to 2A load.

Overall, I would recommend to use DC/DC set to 3.3V output voltage and bypass the Wemos' LDO which will eat your battery anyway. In case you don't have any other 5V peripherals of course.

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Re: No wakeup after complete discharge of the batteries

#27 Post by pino_otto » 10 Jan 2022, 02:41

Thank you, for all the suggestions.

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Re: No wakeup after complete discharge of the batteries

#28 Post by pino_otto » 10 Jan 2022, 02:59

According to the datasheet, it seems that also NCP304 can be configured with additional hysteresis. See page 17 here: https://www.onsemi.com/pdf/datasheet/ncp304-d.pdf

But I didn't understand well that example and how much the hysteresis can be extended.

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Re: No wakeup after complete discharge of the batteries

#29 Post by pino_otto » 10 Jan 2022, 13:41

chemmex wrote: 09 Jan 2022, 14:45 There's a battery monitor IC from chinese Consonance Electronics called CN302. It can be used to cut off the load (or shut down the ESP if connected to the EN pin) when the battery voltage drops down to the limit set by resistor divider. It also provides adjustable hysteresis to allow the battery be charged above the "gray zone" so that it can start up the ESP reliably.

It comes in SOT23-6 package and is quite cheap.

http://www.consonance-elec.com/pdf/data ... -CN302.pdf

https://www.aliexpress.com/item/1005002 ... 6e1eEgWkeE
I will try to buy and use CN302.
According to the hysteresis formula on page 5 of the datasheet, I calculated the following resistances for a hysteresis from 3.3V to 4.0V:
R1=253k
R2=121k
R3=26k

Do you think that those values are reasonable?

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Re: No wakeup after complete discharge of the batteries

#30 Post by pino_otto » 10 Jan 2022, 14:35

Do you have any suggestions about how to use SMD components (such as the CN302) with the breadboard?

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Re: No wakeup after complete discharge of the batteries

#31 Post by Ath » 10 Jan 2022, 15:03

This? https://www.aliexpress.com/item/4000042467857.html

Or else just solder (short) breadboard wires to the connections and plug those into the breadboard, for this voltage converter, that shouldn't be much of a problem
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Re: No wakeup after complete discharge of the batteries

#32 Post by chemmex » 10 Jan 2022, 15:15

According to the datasheet, it seems that also NCP304 can be configured with additional hysteresis. See page 17 here: https://www.onsemi.com/pdf/datasheet/ncp304-d.pdf
This could make sense, but for desired hysteresis and Hi/Lo voltages this circuit will draw around 1mA in OFF state, which will decrease charging current and thus make recovery time longer.
According to the hysteresis formula on page 5 of the datasheet, I calculated the following resistances for a hysteresis from 3.3V to 4.0V:
R1=253k
R2=121k
R3=26k
I would suggest you ~3.2V for Vhi and ~2.9V for Vlo, this gives roughly R1=430K, R2=270K, R3=30K. Also take into account that the charge speed and recovery time will depend on your battery capacity.

For breadboarding SOT23 component you can use adapter board like this:
https://aliexpress.com/item/10050014632 ... 6216987111
Last edited by chemmex on 10 Jan 2022, 16:42, edited 1 time in total.

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Re: No wakeup after complete discharge of the batteries

#33 Post by pino_otto » 10 Jan 2022, 15:31

Thanks all for the many suggestions. I will try them.

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Re: No wakeup after complete discharge of the batteries

#34 Post by TD-er » 10 Jan 2022, 16:28

Depends on the battery you use.
Also the suggested voltages are for measuring directly on the battery.
If there is a diode between battery and where you measure voltage, you have to take into account the voltage drop over the diode. (measure using a multimeter, not just assume from the datasheet)

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Re: No wakeup after complete discharge of the batteries

#35 Post by pino_otto » 11 Jan 2022, 15:53

ok, I understand

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Re: No wakeup after complete discharge of the batteries

#36 Post by pino_otto » 20 Jan 2022, 13:12

pino_otto wrote: 10 Jan 2022, 13:41 I will try to buy and use CN302.
According to the hysteresis formula on page 5 of the datasheet, I calculated the following resistances for a hysteresis from 3.3V to 4.0V:
R1=253k
R2=121k
R3=26k

Do you think that those values are reasonable?
I am using 3 potentiometers to set R1, R2, R3 exactly as the above values, but the /LBO signal is going up when the battery voltage is ~3.5V, instead of the calculated 4.0V.
There is no diode between battery and where I measure voltage.

Do you have any idea why this is happening?

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Re: No wakeup after complete discharge of the batteries

#37 Post by TD-er » 20 Jan 2022, 13:52

Can you draw (or link) to the schematics of what you're making?
Is this the same datasheet as you're using? https://datasheetspdf.com/pdf-file/1257 ... CE/CN302/1

The rising threshold seems to be 4.00V
The falling theshold is 3.3V if I made no mistakes in my calculation.
So what are you testing with this circuit?
Starting at some 4.2V on a bench power supply and slowly dailing the voltage down, to similate a battery discharge?

When using potentiometers, you may have added extra distance between the chip and the resistors.
These may also act as an antenna, so I guess adding some capacitors over the resistors (close to the chip) may be a good idea to reduce potential noise.

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Re: No wakeup after complete discharge of the batteries

#38 Post by pino_otto » 20 Jan 2022, 14:29

Yes, it is the same datasheet: http://www.consonance-elec.com/pdf/data ... -CN302.pdf

I am implementing the schematics on Page 2, Figure 1. The Vbat is the voltage taken directly from the + head of the battery (18650).

Yes, your calculation is correct. I am expecting the rising threshold at 4.0V and the falling threshold at 3.3V. But I see that the rising threshold seems to be ~3.5V, because at ~3.5V the signal /LBO (active low) is going from 0V to ~3.5V.
Now I am using directly the battery, I will try to simulate the battery with a variable voltage power supply.

What values for the capacitors to add?

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Re: No wakeup after complete discharge of the batteries

#39 Post by TD-er » 20 Jan 2022, 14:32

Depends a bit on the type of noise.
Typically I would use 100 nF to begin with.
You can also combine a smaller one and a larger one to filter out higher and lower frequency noise, but that makes it harder to add them close to the chip.
So just start with 100 nF

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Re: No wakeup after complete discharge of the batteries

#40 Post by pino_otto » 21 Jan 2022, 12:16

I didn't solve yet the problem of the exact rising and falling threshold voltages for CN302, but I have found another problem.

Even if I can control the enable of the DC/DC converter --> wemos exactly at 4.0V, the battery cannot be charged enough to provide enough current to the wemos. So the ESP cannot boot properly and goes into a limbo status, from where it cannot exit until a manual reset is done.

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Re: No wakeup after complete discharge of the batteries

#41 Post by TD-er » 21 Jan 2022, 15:45

Please also keep in mind that if the ESP was shutdown due to low voltage, you may need to power cycle it as it may never boot again on itself until you do.
So how do you turn the ESP "on" ?
Just triggering the "EN" pin on the ESP, or via a FET on the power line of the ESP?

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Re: No wakeup after complete discharge of the batteries

#42 Post by pino_otto » 22 Jan 2022, 06:09

Now I turn the ESP "on" by connecting it to the output of a DC/DC converter that has an "EN" pin.
That "EN" pin is controlled by the CN302. I found that the "EN" is at ~3.5V so it enables the output of the DC/DC converter, but the output voltage of the DC/DC converter is only ~1.0V. I think that it happens probably because the battery has not enough charge to provide the needed current to the DC/DC converter and so to the ESP. Then the ESP doesn't boot again on itself.

How can I use a FET to power "on" the ESP, only when there is enough current?

PS: how can I attach pictures here in the forum?

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Re: No wakeup after complete discharge of the batteries

#43 Post by chemmex » 22 Jan 2022, 07:29

If you have charged the battery to 3.5V, you can connect the Wemos directly without DC/DC to test if there's enough power to start up the ESP. Just to make sure your battery is capable of the required current in that state of charge. Healthy 18650s can drive the ESP down to 2.8V.

Also there is possibility that DC/DC converter is causing trouble with very high startup load.

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Re: No wakeup after complete discharge of the batteries

#44 Post by Ath » 22 Jan 2022, 09:31

pino_otto wrote: 22 Jan 2022, 06:09 PS: how can I attach pictures here in the forum?
Below the 'Post a reply' text area, there are 2 tabs, Options and Attachments. There you can select the file you want to attach.
Screenshot - 22_01_2022 , 09_27_11.png
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After adding a file, there is a button 'Place inline' that inserts a reference to the file in your reply, at the current cursor location:
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Oh, and the 'Delete file' button does exactly what it suggests ;)
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Re: No wakeup after complete discharge of the batteries

#45 Post by TD-er » 22 Jan 2022, 10:03

You can also add a capacitor over the EN and GND pin of the ESP.
This will delay the power up of the ESP to give the DC/DC converter some time to stabilize.

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Re: No wakeup after complete discharge of the batteries

#46 Post by pino_otto » 22 Jan 2022, 15:27

chemmex wrote: 22 Jan 2022, 07:29 If you have charged the battery to 3.5V, you can connect the Wemos directly without DC/DC to test if there's enough power to start up the ESP. Just to make sure your battery is capable of the required current in that state of charge. Healthy 18650s can drive the ESP down to 2.8V.

Also there is possibility that DC/DC converter is causing trouble with very high startup load.
Ok, I will try that.

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Re: No wakeup after complete discharge of the batteries

#47 Post by pino_otto » 22 Jan 2022, 15:28

Below the 'Post a reply' text area, there are 2 tabs, Options and Attachments. There you can select the file you want to attach.

After adding a file, there is a button 'Place inline' that inserts a reference to the file in your reply, at the current cursor location:

Oh, and the 'Delete file' button does exactly what it suggests ;)
Ok, thanks.

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Re: No wakeup after complete discharge of the batteries

#48 Post by pino_otto » 22 Jan 2022, 15:30

TD-er wrote: 22 Jan 2022, 10:03 You can also add a capacitor over the EN and GND pin of the ESP.
This will delay the power up of the ESP to give the DC/DC converter some time to stabilize.
I am using a wemos d1 mini. That board does not have an EN pin, as far as I know.

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Re: No wakeup after complete discharge of the batteries

#49 Post by TD-er » 22 Jan 2022, 16:30

The older versions with the "metal cap" over the ESP and flash chip do have the EN pin available on those castellated copper pads around the ESP12E/F module.
On later ones the EN pin is hardly reachable as the pads on the ESP chip itself are really tiny and on the bottom of the chip.

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Re: No wakeup after complete discharge of the batteries

#50 Post by pino_otto » 23 Jan 2022, 07:49

I am now trying a different approach. Instead of using the TP4056, I am trying to use this small UPS board:
photo_2022-01-23_14-42-58.jpg
photo_2022-01-23_14-42-58.jpg (111.15 KiB) Viewed 25875 times
photo_2022-01-23_14-42-54.jpg
photo_2022-01-23_14-42-54.jpg (138.22 KiB) Viewed 25875 times
photo_2022-01-23_14-42-49.jpg
photo_2022-01-23_14-42-49.jpg (126.96 KiB) Viewed 25875 times
I will see if that can solve the boot and shutdown problems related to low voltages at ESP.

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