#400 The Best Power Source for ESP32/ ESP8266 Projects

Summary

This video script offers a comprehensive guide for powering small projects with a focus on 3.3-volt microcontrollers like the ESP32. The presenter discusses five common use cases: mains-powered devices, solar-powered devices, battery-operated continuous usage, devices running 24/7 with periodic wake-ups, and event-triggered devices. Solutions include USB power for mains, solar panels with battery backup for outdoor use, and various battery options for portable and low-power applications. The script also addresses design considerations, such as power regulators, deep sleep modes, and non-volatile memory for data retention. A decision tree is provided to help viewers choose the best power solution for their specific project needs.

Takeaways

• 🔌 The video discusses powering small projects with a focus on 3.3-volt microcontrollers (MCUs), using the ESP32 as an example.
• 🛠️ There's no one-size-fits-all power solution, so the video presents different strategies for five common use cases.
• 🏠 For mains-powered devices, the author recommends using standard USB or 5-volt powered development boards and a USB power brick for compact setups.
• 🌞 Solar power is suggested for outdoor applications, with small solar panels and a 3.7-volt battery to store energy, along with a 3.3-volt regulator for the MCU.
• 🔋 Portable battery-operated devices for short operations can use boards with built-in displays and GPS, like the TTGO boards, which are favored for their compactness and features.
• 🕒 Devices that run 24/7 and wake up periodically should focus on low power consumption, often using replaceable batteries due to the simplicity and longevity.
• 🛑 For devices triggered by events and working in short moments, two approaches are presented: deep sleep mode or complete shutdown with a mechanical switch.
• 🔋 The video mentions the use of LiFePO4 batteries as a good alternative to Li-ion batteries for low power consumption devices due to their chemistry and availability.
• 📶 The author advises caution with different versions of development boards, especially regarding pinouts and power requirements, to avoid compatibility issues.
• 🛠️ Additional circuitry may be needed for mechanical switch-based devices to ensure reliable operation and message transmission.
• 🔄 The importance of using non-volatile memory or EEPROM for storing data in devices that completely power off is highlighted to prevent data loss.

Q & A

What are the five most popular use cases for powering small projects mentioned in the script?

The five use cases are: 1) Devices powered by mains; 2) Solar-powered devices; 3) Battery-operated devices for continuous usage with short operations; 4) Battery-operated devices that run 24/7 and wake up regularly; 5) Devices that monitor an event and work for short moments.

Why does the script focus on 3.3 volts for powering MCUs and sensors?

The script focuses on 3.3 volts because most current MCUs and sensors work on this voltage, and it uses the ESP32 as an example for the concepts.

What is the recommended power supply for mains-powered devices in the script?

For mains-powered devices, the script recommends using cheap standard USB or 5-volt powered development boards and a USB power brick for power.

How does the script suggest dealing with power outages for mains-powered devices?

For dealing with power outages, the script suggests using battery-operated ports tested in a previous video, which have the needed circuitry to charge a Li-ion battery and can survive power outages for many hours.

What type of solar panel and battery combination is suggested for outdoor applications in the script?

For outdoor applications, the script suggests using a 5.5 or 6-volt solar panel with a TP-4056 Li-ion charger and a power path to charge a 3.7-volt battery.

Why is a 3.3-volt regulator needed when using a 4.2-volt maximum battery with a 3.3-volt MCU?

A 3.3-volt regulator is needed to step down the battery voltage because most 3.3-volt MCUs are not rated up to the 4.2 volts maximum of those batteries.

What is the preferred method for powering portable devices used for short operations like weather balloon receivers?

The preferred method is using TTGO boards with a built-in display and, if needed, an SMA connector for antenna connection.

How does the script suggest optimizing battery life for devices that run 24/7 and wake up periodically?

The script suggests omitting a built-in charging circuit and using replaceable batteries, as replacing batteries annually is often easier than recharging remote devices.

What is the advantage of using mechanical switches for devices that are triggered externally, like a mailbox notifier?

Mechanical switches allow the device to be completely off and not consume current when not triggered, which is excellent for situations where triggers are infrequent.

How can data be retained when the MCU is switched off in devices that use mechanical switches?

Data can be retained by storing it in non-volatile memory or EEPROM before the MCU is switched off, although this method has a limited number of write cycles.

What is the purpose of the flow diagram provided at the end of the script?

The flow diagram is intended to help users decide the best power solution for their projects by answering a series of questions related to their specific use case.

Outlines

00:00

🔌 Powering Small Projects with Various Use Cases

The speaker introduces a video focused on powering small projects, highlighting a curated list of solutions for five common use cases. The video aims to guide viewers on choosing and building power solutions for their projects. The presenter, known for his Swiss accent, emphasizes the importance of focusing on different use cases rather than a one-size-fits-all approach. The discussion primarily revolves around 3.3-volt microcontrollers (MCUs), using the ESP32 as an example. The speaker also mentions the importance of subscribing to the channel for regular updates on sensors and microcontrollers.

05:02

🌞 Solar and Battery Power Solutions for Outdoor Devices

This paragraph delves into the specifics of powering outdoor devices, such as solar-powered light sensors. The speaker recommends small and affordable solar panels paired with a battery to provide continuous power even when sunlight is not available. A 5.5 or 6-volt solar panel is suggested, along with a TP-4056 Li-ion charger and a power path management circuit. For voltage regulation, a 3.3-volt regulator is necessary due to the maximum voltage of 4.2 volts of the battery, which is higher than the voltage rating of most 3.3-volt MCUs. The use of a PCB with an HT7333 regulator and capacitors is recommended for minimal power consumption during deep sleep. Programming is facilitated through a USB-to-serial adapter with a 3.3-volt feature, and the speaker advises caution when using standard battery-operated boards due to voltage limitations.

10:04

🔋 Options for Battery-Operated Devices with Continuous and Event-Based Usage

The speaker discusses two types of battery-operated devices: those used for continuous operations and those that operate on event triggers. For continuous usage, the focus is on minimizing power consumption, with the speaker suggesting the use of replaceable batteries due to the ease of replacing over recharging, especially for devices that run for extended periods. For event-based devices, two approaches are presented: keeping the MCU in deep sleep mode to conserve power or completely switching off the device with a mechanical switch. The latter is advantageous for infrequent triggers as it eliminates power consumption when not in use. The speaker also addresses the challenge of ensuring that a mechanical switch provides sufficient power to transmit a message and proposes a solution involving additional circuitry with FETs. Lastly, the importance of storing data in non-volatile memory before the MCU is switched off is highlighted.

Keywords

💡Powering

Powering refers to the process of providing electrical energy to a device or system. In the context of the video, powering is central to the theme as the creator discusses various methods to supply energy to small projects, such as using mains power, solar power, or batteries. The video aims to guide viewers on how to choose the appropriate power source for different use cases.

💡ESP32

ESP32 is a microcontroller unit (MCU) that is widely used in small projects due to its Wi-Fi and Bluetooth capabilities. The video uses the ESP32 as an example to illustrate how different power solutions can be implemented for various applications. It is mentioned as a common component that requires a 3.3-volt power supply.

💡Mains Power

Mains power, also known as mains electricity, is the general term for the standard AC electrical supply found in many countries. The video discusses using mains power for devices like a weather station receiver, emphasizing its convenience for projects that do not require energy conservation.

💡Solar Power

Solar power is the energy derived from sunlight, typically captured by solar panels. The script mentions solar power as a viable option for outdoor applications, such as powering a light sensor, where a small solar panel combined with a battery can provide a sustainable power source.

💡Battery-Operated Devices

Battery-operated devices are those that run on batteries as their primary power source. The video outlines different scenarios for battery use, such as devices used for continuous operation, short operations, and those that run 24/7 but wake up periodically.

💡3.3 Volt Regulator

A 3.3 volt regulator is a component that ensures a stable 3.3-volt output, which is necessary for many microcontrollers, including the ESP32. The video explains the need for a 3.3 volt regulator when using batteries that can exceed this voltage to prevent damage to the MCU.

💡Deep Sleep

Deep sleep is a power-saving mode in which a device or microcontroller consumes minimal power. The video highlights the importance of deep sleep for extending battery life in devices that need to operate for extended periods without frequent charging.

💡Microcontroller Unit (MCU)

A microcontroller unit (MCU) is a small computer that integrates a processor core with memory, and programmable input/output peripherals. The video focuses on MCUs that operate on 3.3 volts, discussing how to power them efficiently for various applications.

💡USB Power Brick

A USB power brick is a compact power adapter that provides power to USB devices. The script describes using a USB power brick for powering mains-powered devices, offering a simple and cost-effective solution for projects that do not require energy conservation.

💡LiPo Battery

LiPo, short for lithium-polymer battery, is a type of rechargeable battery known for its high energy density and small size. The video discusses using LiPo batteries for devices that can handle the charging circuitry and need to survive power outages.

💡TTGO Boards

TTGO Boards are a series of development boards that often include features like built-in displays and wireless communication modules. The video mentions TTGO boards as a preferred choice for portable devices used for short operations, highlighting their versatility and compactness.

💡AXP192 Chip

The AXP192 is a power management chip that can handle various power-related functions, including charging and power path management. The video describes the use of the AXP192 chip in devices like the T-Beam, which is designed for location-based applications and requires efficient power management.

💡Non-Volatile Memory

Non-volatile memory is a type of memory that retains data even when power is not supplied. The script suggests using non-volatile memory or EEPROM to store information in devices that may be completely switched off, ensuring data is not lost.

Highlights

Introduction to the video on powering small projects with a focus on 3.3-volt microcontrollers (MCUs) and sensors.

Discussion on the lack of a one-size-fits-all power supply and the importance of focusing on different use cases.

Explanation of the first use case: mains-powered devices, utilizing standard USB or 5-volt powered development boards.

Recommendation of a mini board for mains-powered projects due to its small size and availability of many pins.

Suggestion to use a cheap USB power brick or a compact 5-volt power supply for power in mains-powered projects.

Introduction to the second use case: solar-powered devices, emphasizing the use of small and cheap solar panels.

Recommendation of a 5.5 or 6-volt solar panel with a TP-4056 Li-ion charger for solar-powered projects.

The need for a 3.3-volt regulator between the battery and the MCU in solar-powered projects.

Use of a USB to serial adapter with a 3.3-volt feature for programming solar-powered projects.

Introduction to the third use case: battery-operated devices for continuous usage without sleep.

Recommendation of TTGO boards for portable devices due to their built-in display and compact size.

Explanation of the fourth use case: battery-operated devices that run 24/7 and wake up periodically.

Discussion on the benefits of using LiFePO4 batteries over Li-ion for low power consumption devices.

Introduction to the fifth use case: devices that monitor an event and only work for short moments.

Suggestion to use deep sleep mode or a mechanical switch for event-triggered devices to save power.

Recommendation of the TRIG board for extremely low current draw and periodic wake-ups.

Discussion on the use of non-volatile memory or EEPROM to store information before the MCU is switched off.

Conclusion emphasizing the importance of distinguishing use cases to determine the best power solution.

Call to action for viewers to comment with their use cases or better solutions for community learning.

Presentation of a simple flow diagram for decision making regarding power solutions for different use cases.

Transcripts

are you interested in my way of powering

small projects

after many discussions and evaluations i

created a favorite list with solutions

for the five most popular use cases

why did i choose them and how can you

build them

after the video you should have a

decision tree for your future projects

gritsy youtubers here is the guy with

the swiss accent with a new episode and

fresh ideas around sensors and

microcontrollers

remember if you subscribe you will

always sit in the first row

because most of the current mcu's and

sensors work on 3.3 volts i will

concentrate on this voltage and use the

esp32 as an example

however all concepts can be used for

other 3.3 volt mcus

unfortunately there is no

one-size-fits-all power supply this is

why i do what we always should do

i focus on different use cases

the first use case is about devices

powered by mains like this receiver for

my weather station or the bluetooth

receiver for my xiaomi body scale of

video number 307

number two

solar-powered devices like my light

sensor

number three battery-operated devices

for continuous usage like these tiny

receivers for weather balloons or this

lora tracker

both devices are only used for short

operations

use case number four battery-operated

devices that run 24 x 7 and regularly

wake up

like temperature and humidity sensors

number five

devices that monitor an event and only

work for short moments like this mailbox

notifier or this amazon dash button what

is my solution for the simplest use case

the mains powered devices

i use cheap standard usb or 5 volt

powered development boards because these

boards do not have to save energy for

this application

they also offer a usb connector for

programming and debugging

by the way this mini board is my current

favorite because it offers many pins and

is small

most of the time i solder the wires

directly onto the pcb without pin

headers

for power i usually use a cheap usb

power brick and

if i want everything in a single and

compact case i add such a small 5 volt

power supply right in the project case

as i did for this home automation

watchdog of video number 385

by the way you find all links to the

products i use in the video description

if you fear power outages i suggest

using one of those battery-operated

ports tested in video number 387

they all have the needed circuitry to

charge a lion battery

such boards will survive power outages

of many hours without problems

here my favorite has the same form

factor with additional battery circuitry

please pay attention to use either a

short or a quality usb cable otherwise

the esp32s can create brown outs because

of the cable loss

what about use case number two

it is mainly for outdoor applications

where we can use solar power

these days small and cheap solar panels

provide enough energy for a typical

project

of course we need a battery to bridge

times without sun

no not a tesla powerball just a small

single lion sill

in this scenario we do not have to save

every microampere i suggest using a 5.5

or 6 volt solar panel then we can use a

simple

tp-4056 lyon charger with a power path

as shown in video number 383 to charge a

3.7 volt battery

because the maximum voltage of those

batteries is 4.2 volts and most 3.3 volt

mcus are not rated up to this voltage we

have to add a 3.3 volt regulator between

the battery and the mcu

the best solution is to use such a pcb

with a bare module an ht7333

regulator and one or two capacitors as

suggested by the datasheet

these boards only consume microamperes

during deep sleep

for programming i use such a usb to

serial adapter make sure you have a

model with a 3.3 volt feature

you could also use standard battery

operated boards because the chips on

these sports should support up to 6.5

volts but again please consult the

diagram and the data sheets before you

try

by the way i usually remove all leds on

those boards because they just consume

power if deployed in a case

can you also use standard development

boards without the battery

yes but i suggest using an hd 7333

regulator and connect power to the 3.3

volt because the standard

ams-1117 regulators stop working at

about 4 volts

low dropout is only marketing in this

case keep in mind that these boards need

quite some power during deep sleep

because of the additional parts on the

board

next is use case number three portable

devices used for short operations like

the receiver to search for weather

balloons or mapping gateway coverage

they are battery operated and do not

sleep at all

here i love those ttgo boards because

they have a built-in display

you even get versions with the laura

chip on board then you can decide if you

want an sma connector mounted on the

board or connected via a pigtail

creating cases is easier for the version

with a pigtail however i prefer the sma

version

for all location-based applications the

t-beam is perfect it has a battery a gps

and a lora chip on board and is very

compact if you want to add an oled

display please pay attention to choose

the right one with the correct pin out

maybe you order it together with a board

then you know at least who is

responsible if it does not fit by the

way it uses the axp192

chip for powering

this is a very capable chip which also

has a built-in on off function for

example

the only pain in the butt for most tt go

boards is the different versions with

different pin outs

their naming is not at all intuitive and

you have to pay extreme attention to

find out which version you have and

which pin out you have to use

be also aware that they often do not use

standard pins for i square c

so you have to select the right board in

your ide otherwise the pin definitions

are wrong and your display will remain

black or your sensors will not work

at least they have all information

including diagrams published on github

i really hope they will learn something

and give their boards clear names and

print them on the boards it seems that

the newer ones at least have the

versions marked on the silk screen what

about use case number four which is also

battery operated but runs 24 times 7.

to get a decent battery life these

devices sleep most of the time and

periodically wake up

here every micro ampere counts because

it reduces battery life

after some iterations i concluded that

because these devices run for month or

even years on one battery omitting a

built-in charging circuit considerably

reduces the complexity of our design and

increases its autonomy

maybe you even use disposable batteries

instead of rechargeable ones

replacing batteries once a year is often

easier because charging a battery takes

much longer than just replace it

unfortunately i do not see a lot of

ready-made boards for this use case

maybe we will see a change in the future

the simplest version uses a live fipo 4

battery instead of a lighon battery and

connects it directly to a bare bone

module

because live f4 batteries have a maximum

voltage of 3.6 volts we do not need a

regulator and so we can avoid its losses

liveapo4 batteries became more popular

over the years and you get them in

various versions

i will show you the proper usage of such

batteries in a future video

to extend battery life even further you

can use the trig board which is

optimized for extremely low current draw

and offers periodic wake ups without

deep sleep

if you want to use disposable batteries

you have the choice of two or three aaa

or 3 volt

cr123a lithium cells

because the maximum voltage of 3 aaa

cells is more than 3.6 volts you need a

voltage regulator and with only two of

them your processor will stop working

before they are empty but they have a

lower sales discharge current

than rechargeable batteries and also do

not need a low voltage protector that

also consumes a few microamperes

deep sleep has two advantages the mcu

can wake up without an external trigger

and the rtc memory in the esp32 keeps

its information during deep sleep

other chips like the old atmel also keep

their data during deep sleep

what is left

a use case similar to the one just

discussed the main difference is that an

external source triggers it

good examples are this amazon dash clone

or this mailbox notifier maybe i will

show you my newest design in a future

video

here we have two possibilities we can

deep sleep the board and wake it up with

an external triggering pulse

or we switch it completely off with a

mechanical switch

if we use deep sleep the design

considerations are the same as in use

case number four because the mcu is

always on and most of the time in deep

sleep however if we can use a mechanical

switch we can get an additional

possibility we can switch the board

completely off and switch it on with a

mechanical switch

this has the advantage that it does not

consume current if not triggered

especially for situations we do not

expect many triggers per time this is an

excellent solution

a window sensor against burglars for

example will hopefully not trigger too

often or my mailbox notifier only

triggers twice a day once for my wife's

newspaper and once for the packets from

china for me

the rest of the time it is completely

switched off

one problem has to be solved for many

applications

if the mechanical switch is on too short

for transmitting a message we have to

add some additional circuitry

in video 101 i showed you a possibility

with only one p-channel fit

however it is not reliable because it

depends on the inner circuit of the mpu

this is why i propose to add a second

fit here is the diagram

these transistors are connected in

parallel to the mechanical switch and

are operated by a pin

as soon as the mechanical switch powers

the mcu it switches the n-channel fit on

now the gate of the p-channel fet is at

nearly zero volts and a parallel path

exists to power the mcu

when the switch is off the esp32 still

is powered through the p-channel fit

as soon as all tasks are done the mcu

switches itself off and waits for the

following mechanical trigger

if you use a to-220 and an smd fit you

can easily create such a small pcb

the threadboard also works for this use

case

and tobias built the microwave capper

for the same purpose

these boards also switch the mcu off and

therefore it loses all data

suppose you want to keep the information

store it in a non-volatile memory or

eeprom before the mcu is switched off

keep in mind that ee prompts wear out

and you probably cannot do this for more

than ten thousand times

but this is enough for my mailbox

notifier

did i forget your use case or do you

have better solutions

please comment and we will learn

together

i promised a simple flow diagram for

decision making here it is

just answer the questions and you will

get the use case and what solution i

propose

what do we have to remember

there is no one size fits all but if we

distinguish use cases we can determine

the best solution for each case

most current boards and projects use

lion batteries however liveapo 4

batteries often are the better choice

they become more and more available

devices with low power consumption do

not need an onboard charging circuit it

is often better to use replaceable

batteries for them because replacing a

battery every year is easier than

recharging remote devices

unfortunately we still do not find many

such devices on the market

the trick board and the microwave copper

are interesting boards for special cases

however they are not cheap

as always you find all the relevant

links in the description

i hope this video was useful or at least

interesting for you if true please

consider supporting the channel to

secure its future existence thank you

bye