That looks like a great idea and really cheap. If designing my own boards for a production environment I would definitely use it. Some dev ESP32 boards have an enable pin so this would work. Others would not so you would probably have to come up with a power supply cutoff of some sort.

Hi.
That’s a great tip!
Thank you so much for sharing 🙂

Thank you Sara.

How would you use a TP4056 and a voltage supervisor together for a single cell 18650, solar, ESP32 project?

Previous article:  “Power ESP32/ESP8266 with Solar Panels (includes battery level monitoring).”  Wanting to add a voltage supervisor and a FET to switch, ESP32 off at low voltage.

Mr. Spiess in his video; on  voltage supervisors, he uses a KA75290 voltage supervisor and a IRLZ44N, FET to switch device off at low voltage.  How would these components be connected in the previous article diagram that shows Solar cells, TP4056, 18650 battery and LDO regulator?

William

Hi.

I don’t have a voltage supervisor to experiment with. So, I don’t know if what I’m saying will work on the solar panel circuit or not. But what I understand is that you want to keep the ESP32 RST button to LOW when the input voltage is lower than 3.3V.

So, connect the voltage supervisor input pin to the input voltage (battery), GND to GND and the output pin to the ESP32 enable pin. When the voltage goes below 3.3V, the output pin goes LOW and pulls the ESP32 enable pin to LOW to prevent it running.

I think you should keep the circuit shown in the tutorial but connect the voltage supervisor input pin to the battery output voltage.

I hope this helps, but as I’ve told you I haven’t tested this.

Regards,
Sara

Would like to turn off the supply voltage to the ESP32 when the 18650 falls to 2.9 volts; which turns off the IRLZ44N FET shutting off the supply voltage to the ESP32.  Is 2.9 volts too low for a 18650?

I have a basic schematic; using part of the previously noted tutorial, diagram for illustration.  Schematic is untested.

Does schematic look correct?

How can the resistor between Voltage Supervisor and FET be calculated?  Believe the resistor between LDO and Voltage supervisor would be a pull-up resistor.

Regards,
William

Hi again.
For most 18650 batteries, the working voltage is between 2.5 volts and 4.2 volts. So, 2.9V should be ok.
As for the circuit, I recommend taking a look at the TC54VN2902EZB datasheet. It shows a circuit example for that kind of application: https://ww1.microchip.com/downloads/en/DeviceDoc/20001434K.pdf –> see page 6.
Your circuit seems slightly different. But with circuits there are many ways to achieve the same thing. 
I hope this helps and I’m sorry if I can’t help much. I haven’t experimented with that component before and I’m far from being an “expert” in circuits.
Regards,
Sara
 

Thank you Sara.  I have TC54VN2902EZB and IRLZ44N now; now to keep the smoke inside components…  I see from the datasheet you referenced in Figure 4.2 (“Other applications”) the voltage supervisor can be directly connected to the Gate of a MOSFET.  Will give it a go…

Reviewing Mr. Spiess’s video; this is the circuit for voltage supervisor with a MOSFET:
Voltage Supervisor Battery Cut-off with MOSFET

William

Ok.
Then, let us know how it went.
Regards,
Sara

Will do Sara.  Waiting on some components yet to arrive.  Miss the time we could purchase components locally.
 
Found a detailed article on the TP4056. 
 
Best Regards,
William
 

Great!
Thanks for sharing.
Then, tell us how it went.
Regards,
Sara

Updated 10/6/2020; circuit correction.

Breadboarded this circuit; disconnecting Vout of the voltage supervisor at the Gate of Mosfet turns off the LED, otherwise while powered, LED is ON.

Will vary voltage supervisor, Vin to below threshold; this will confirm circuit works as intended.  Yet to be done.  Looks promising so far…

William

Great!
Expecting some good news about that circuit 🙂
Regards,
Sara

Voltage Supervisor has a Vdet of 2.9 Volts; which produces a Logic LOW, voltage.

Observation; applying battery voltage of 2.6 volts, LED is “off.”  Voltage supervisor causes Gate of MOSFET to switch by sending Logic, LOW to Gate.    Applying 3.3 volts to circuit; LED is “on.”  This part of the Solar Supply is working as intended.

William

Results of voltage measurements:

Charged Battery

Discharged Battery at 2.93 Volts

Circuit disconnects load for Solar cell to charge battery using TP4056 and a single, 18650 battery.

William

Hi.
Thanks for sharing your results.
It seems that everything is working as expected. Right?
Regards,
Sara

Need to change Vin on Battery Suppervisor to Battery + Out..  You had pointed that out previously; missed that statement.  Tested Solar panel this afternoon; panel is outputing 5.71 V.  (bright Sun) and 4.15 V. between battery connections (no battery.)   Working on getting everything onto strip board.  72 year old eyesight does not help much…

Corrected schematics

Added two capacitors used in your tutorial.

William

Hi again.
Congratulations for your project. I would love to see your stripboard once it is ready.
So, if you want to share it here, it would be great!
Keep up the good work.
Regards,
Sara

Solar Power assembly on Stripboard

LDO, Voltage regulator is outputing 3.3 volts.  Voltage from Battery + is good at Vin of Voltage supervisor; however, I have no Vout at the Voltage supervisor.  Need some time to do more troubleshooting.  Will report back.

Stripboard copper traces

William

Sorry for the delay; took time off to visit a sick friend.

Isolated problem to a defective voltage supervisor; replaced with new voltage supervisor.  VOut of voltage supervisor is normally a logic LOW, turning MOSFET switch ON, with led ON.  When battery voltage reaches 2.9 V. VOut of voltage supervisor becomes a logic HIGH and led is OFF; load has been removed from circuit and TP4056 charges the 18650 battery. Circuit assembly is working correctly…

William

That’s great news!
I’m really happy that you got it working properly!
And thank you for sharing your work 😀
Regards,
Sara

That’s great news!
I’m really happy that you got it working properly!
And thank you for sharing your work 😀
Regards,
Sara

Revision, low-side switch.

Solar Power Assembly Schematic

Best Regards,
William

Hi.
Thank you so much for sharing.
Can you share this on our Facebook group? I think it will have more engagement.
https://www.facebook.com/groups/RandomNerdTutorials
Thanks 🙂

Thank you Sara; have posted to “Facebook.com/groups/RandomNerdTutorials.”
 
William 

Thank you!

Interesting product; DFRobot, Solar Power Manager 5V; looks promising for IoT projects.
 
DFRobot, Solar Power Manager 5 V product details
 
Also available from the Arduino.cc Store
 
 
 
 

Hi.
Thanks for sharing.
Is it similar to this (https://makeradvisor.com/tools/tp4056-lithium-battery-charger/) but better?
Regards,
Sara

Just ordered one today from “Arduino.cc Store;”  USA Warehouse and less expensive shipping.  Here are the Specs:

SPECIFICATION

• Solar Power Management IC: CN3065
• Solar Input Voltage (SOLAR IN): 4.5V~6V
• Battery Input (BAT IN): 3.7V Single cell Li-polymer/Li-ion Battery
• Charge Current(USB/SOLAR IN): 900mA Max trickle charging, constant current, constant voltage three phases charging
• Charging Cutoff Voltage (USB/SOLAR IN): 4.2V±1%
• Regulated Power Supply: 5V 1A
• Regulated Power Supply Efficiency (3.7V BAT IN): 86%@50%Load
• USB/Solar Charge Efficiency: 73%@3.7V 900mA BAT IN
• Quiescent Current: <1 mA
• Operation Temperature: -40℃～85℃
• Dimension: 33.0mm*63.0mm
• Protection Functions:

1. BAT IN: over charge/over discharge/over current/reverse connection protection
2. 5V/USB OUT: short circuit/over current/over heat protection
3. SOLAR IN: reverse connection protecti

“Regulated Output:  3.3V 1A; 5V 1.5A; 9V/12V 0.5A
NOTE: The input voltage of SOLAR IN SHOULD NOT exceed 6.5V, or the module may be permanently damaged.”
–from DFRobot, product wiki page

Product wiki page

IMHO; has more features listed in specs than the TP4056; perhaps you will do a review or use one in an up coming tutorial.

Hi.
That’s a good idea.
I think I’ll order one.
Regards,
Sara
 

Another look at the TP4056: 18650 Lithium Battery Charger Module Li-ion Charging Board.

Mr. Spiess has released a new video; adding a “power path for the TP4056”:
Cheap and simple Solar Power for our small Projects (ESP32, ESP8266, Arduino)

William

Sharing two “ForceTronics’s,” YouTube video links::

Building a Battery Cutoff Circuit to Prevent Over Discharge of Rechargeable Batteries Part 1

Building a Battery Cutoff Circuit to Prevent Over Discharge of Rechargeable Batteries Part 2

Note: Circuit is an application design for 7 volts!
ABLIC part would need to be spec’ed for microcontroller use.

Regards,
William

Thanks for sharing.
I’ll take a look.
Regards,
Sara

Good Morning,

Is there a need to monitor tp4056 battery with a voltage supervisor to prevent discharging too low?

“Yes, there is a need to monitor a TP4056 battery with a voltage supervisor to prevent discharging too low. The TP4056 does not have a built-in low-battery cutoff, so it will continue to discharge the battery until the voltage reaches a very low level. This can damage the battery and shorten its lifespan. A voltage supervisor can be used to monitor the battery voltage and disconnect the load when the battery reaches a low level. This will prevent the battery from being discharged too low and will extend its lifespan.

The voltage supervisor should be set to disconnect the load when the battery voltage reaches a level that is safe for the battery. For a lithium-ion battery, this is typically around 3.0 volts. The voltage supervisor should also have a low dropout voltage, so that it does not cause a significant drop in the battery voltage when it disconnects the load.”  –Google’s Bard

Here are some of the benefits of using a voltage supervisor to monitor a TP4056 battery:

• Protects the battery from being discharged too low
• Extends the battery lifespan
• Prevents damage to the battery
• Provides peace of mind knowing that the battery is being protected

I have used this approach with a Rolm, BA022CC0WT, 5 pin LDO voltage regulator with an Control/enable pin.  Works well.

Regards,
William

That’s great.
Thanks for sharing your results.
Regards,
Sara