which battery-operated power supply is
best for our project
in this video i have 10 boards for the
raspberry pi
as well as for arduino esp and
stm32 boards we will compare their
features
find out the differences and test them
because of the test results we will not
stop there
we will design our own super power
branded battery power supply
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swiss accent
with a new episode and fresh ideas
around sensors and microcontrollers
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which features should an ideal power
supply have
3.3 volt output 5 volt
usb output usb charging solar charging
charging while powering a device
replaceable batteries
lion or live apo 4 chemistry
variable number of batteries battery low
voltage protection
low voltage signal for mcu a voltmeter
ampere meter small self-discharge
charge indicator can be used as a shield
for a raspberry an esp or even an
arduino
maybe you can add more features that are
essential for you
you will get this chance later in the
video
this is a long list for a particular
project
some of these features are more
important than others
this is why we need an overview and this
is why i bought
these products three single cell modules
all with five volts output and two also
with 3.3 volts
five two cell modules in different
configurations
one module with a flat lyon battery
and one module with four 18650 cells
i checked them out and made this table
with their features
i also added the chips used for the
different functions
this is important to understand how they
work
and maybe later for our superpower
boards
i could have included power banks
however most of them cannot be used for
our purpose
because they switch automatically off at
low currents
or they stop providing energy while
charging
so let's start with the building blocks
of battery operated power supplies
the obvious block is the battery all
tested modules
use lyon batteries with a nominal
voltage of 3.7 volts
all but one use replaceable 18650
or the smaller 16340 batteries
i like this concept because you can
choose your favorite battery type
and you can replace a defective battery
without problems
and you will get this format also in the
future
to add capacity some of the boards at
cells in parallel like that you omit the
need for balancing
and you decide how many batteries you
want to insert
all run also with a single cell the
batteries have to be charged and
protected from overcharging
the most popular ic for this function is
the
tp4056 it is made for 5 volt usb as
input
but in video number 155
it was also very good with six volt
solar panels
these chips all have the needed stuff to
give lyon batteries a long life
like maximum current and over voltage
protection
one thing however is not included
protection against
deep discharge this is very important if
you want a long life for your lion cells
a standard setup for this function is a
dw01
and an 8205 dual mosfet
you find all you need to know about that
combination
if you watch video number 160.
they switch the load off if the battery
voltage is below a certain level
sometimes 3 volts and often 2.4 volts
they also protect it against over
current
so we have the most critical three
blocks for a
operated device now we need one or two
more
if we want 3.3 volts we could connect a
low dropout regulator or ldo directly to
the battery
simple and efficient but if your battery
voltage goes below
around 3.5 volts your output voltage
starts to drop
this is not a big issue for most mcus
like the esp8266
or esp32 they should run on less than 3
volts
but raspberry pi's are very picky and
need an absolute constant voltage
because 5 volts are higher than the
battery voltage
we need a boost converter all boards
with 3.3 volt
output connect the ldos to the 5 volt
rail
and so get a stable 3.3 volts also at
low battery levels but it wastes a lot
of energy
not suitable for low power devices
without
solar panels for these booster chips
we find a wider variety like the fp6298
or the mt-3608 which is
interesting because of its high
switching frequency
this enables the usage of smaller
inductors and capacitors
if we have a closer look at the ap 2016
we see that many of these specialized
chips come from chinese manufacturers
and are not well documented for western
people sometimes
information is hard to find some
modules use completely integrated
so-called powerbank ics
like the ip5306 they contain all
critical functions
except the 3.3 volt regulator
in this spreadsheet we have the data of
10 different boards
but how to go on we have to specify
the needs of our project a ups
for the raspberry pi 4 for example
first we need protection circuits for
the battery against
overcharge and under voltage fortunately
all modules provide this functionality
good next we set the filter to
raspberry and get these two boards
both can be mounted below the raspberry
pi
so you still can mount a cooler on the
raspberry
very good the maximum current is
three ampere and the two batteries can
feed a raspberry for more than 10 hours
also good and they can be charged
while the raspberry pi is running
the newer port has in addition to the
battery functions
a real-time clock and a volt
and amper meter the volt and ampere
meter
unfortunately is mounted at the output
and therefore only measures the usb
voltage
useless for a battery operated raspberry
because we need a signal to shut it down
before the battery is dead otherwise it
crashes and can kill the sd card
or lose data so they gave a big chance a
way
to create a perfect raspberry ups
adding a simple voltage detector for a
few cents
would have been sufficient or at least
place the ina-219
between the battery and the booster
let's go on
to the next use case find a battery for
an
autonomous esp8266 or
esp32 project the esps use
deep sleep to extend battery life so we
need a very low discharge current
when the esp sleeps we filter the
self-discharge current
and find three boards with around 60
microamperes
this current is way too high this is
because
all these boards first boost the voltage
to 5 volts
and then reduce it to 3.3 volts
beside that this port has no 3.3 volts
and this only provides 3.0 volts
i have no idea why they choose this
voltage
so also here we do not find a suitable
board
such a board has to have a much lower
idle current
and for sure has to provide 3.3 volts
because we want to use a bare bone esp
module
to save energy and they must not have
such fancy push buttons for on off
these boards often keep switched off
after the battery was discharged
a no go for a remote node
we want either no switch at all or a
simple mechanical one
next project let's assume we want to
extend the battery life with solar
energy
then we need the same specifications as
before
plus a solar charger which can accept at
least
6 volts from a solar panel better would
be more
minimum current is not so important
because these days
solar panels are no more costly a single
18650 cell should be okay for most
situations
maybe even a 16 340 in
areas with lots of sun in winter
but we need 3.3 volts so we can use
these four modules with 3.3 volts and a
tp4056 charging chip
the t-beam would also be suitable for
solar charging
unfortunately it has no 3.3 volt output
and its cn 3065 has no
significant advantages compared with a
simple tp4056
as shown in video number 155
none of them can signal the mcu low
battery voltage
if the sun was not strong enough a pin
to connect a analog
input to the battery voltage would not
cost a fortune
with such a connection the mcu could
measure the voltage
and either go to sleep or if connected
to wi-fi or lora
transmit the voltage level from time to
time as i do this with my light sensor
in node-red i use a telegram bot
to alarm me when i have to replace the
battery
by the way here is another trick for
connected sensors
my sensors regularly send data each time
a packet arrives
this timeout node is reset i set its
timeout period to at least
twice the time between packets from my
sensor
the timeout node is also connected to a
telegram bot
which sends me a message when no packets
arrive
anymore i had an occasional software
error in my awning remote control
which made that it crashed and did not
recover
first i used my wife as an alarm system
always when the awning did not work she
signaled me
something is wrong dear mr engineer with
a specific
undertone of course since then i prefer
telegram for that purpose
now i found the error and i do no more
get alarms
not from telegram and not from my wife
very good the same principle is used for
my lora gateway by the way
now it's always up so what about the
other boards
maybe they fit one of your projects for
me
they are more or less useless and this
is
sad so many boards and none really fit
the purpose
this is why i decided to start a new
project
together with you my viewers to design
the best power modules for our projects
you can either work on the
specifications or
if you are good at pcb design or want to
become good
work on designing boards i created a
discord channel called
superpower for the project and a github
repository
also called superpower and i started
with my three use cases
an esp32 ports with an esp32 vrom module
similar to this mini board but with an
16 340 battery and a similar port
that can be powered by a solar panel
both have to have all protections plus
voltage supervisor
which resets the mcu if the voltage is
below the minimum voltage
of the data sheet and a connection to
measure the battery voltage
with an analog pin and a raspberry
shield
for a solar powered raspberry with all
protections
and a voltage supervisor or an analog to
digital converter for measuring battery
voltage
here i would like two 18650 batteries
because the raspberry is power hungry
and
pins for a gps module to get the exact
time these are all use cases
with requirements they answer the
question what
and they have to be finished before we
go on to the design phase
the how will be answered by the guys who
do the design
because i want that everybody can get
such boards
they will be open source their design
has to be manufacturable
by jlc pcb and all parts
should be lcsc parts like that
everybody can order fully assembled
boards
this is important because most of the
modern chips are hard for hand soldering
i also prepared channels for all
building blocks
parallel to defining the requirements
the designers can start to collect
data about the best chips for our
designs
there is also a section about boards we
can learn from
like the 10 boards i have here everybody
is
invited to participate if you want to
lead
one or more of the projects feel free to
contact me
summarized there are many boards
available to power our projects from a
battery
9 of 10 boards in my selection use
replaceable
18650 or 16340 lyon batteries
none uses liveapo4 which probably is a
better technology for 3.3 volt
projects all have the following
functions
lyon charger on the voltage protector
and 5 volt boost converter some also
have
3.3 volts ldos a few
are built as shields either for
raspberries or for arduinos
one board even has a real-time clock and
a voltage and ampere meter
unfortunately the meters are at the
wrong place
and mostly useless the idle current of
all boards is way too high
for low power deep sleep projects none
can read battery voltage
nor has a voltage supervisor against low
voltage brown outs
none of the boards are suitable for my
most common needs
this is why i started a project to
create a perfect board
its name is superpower everybody is
invited to participate
if you want to train yourself as a
project manager or if you want some
visibility for your future shop
feel free to apply for a project leader
role
we will see where we end and if this
time we will get
useful products as always you find all
the relevant links in the description
i hope this video was useful or at least
interesting for you
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thank you bye