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# Confused with selecting the right battery for my project!!

#### jobitjoseph1

Jul 30, 2021
5
I hope I am posting in the right section!

I am building my first battery-powered portable electronics project. The idea is to build a pet tracker that is compact and easy to carry. The operating voltage of my project is 5V (Arduino and Neo6M GPS module), what is the best power source for this project?

My knowledge on the different types of battery available is limited, I have just read and understood this article https://circuitdigest.com/article/different-types-of-batteries

Can anyone suggest a battery that will keep my device running for 7 days. I don't know the exact current consumed by my device i roughly estimate it to be 50mA or less, based on the value shown on my RPS

#### Harald Kapp

##### Moderator
Moderator
Nov 17, 2011
13,651
Lithium batteries are the to-go type in today's world.

Let's calculate the required capacity:
7 days = 7 × 24 h = 168 h
168 h × 0.05 A = 8.4 Ah @5 V- minimum!
Let's assume you use a lithium battery with a step-up regulator to get the 5 V you need.
5 V × 8.4 Ah = 42 Wh.
Assuming an efficiency of the step-up converter of 80 % the true required capacity is 42 Wh / 0.8 = 52.5 Wh minimum.
A lithium battery operates at ~ 3.7 V, so the required capacity is 52.5 Wh / 3.7 V = 14.2 Ah

So you would need a 3.7 V 14.2 Ah lithium battery.
Alternatively you could use 2 Li batteries in series (7.4 V) and a step down regulator. The total capacity is the same, but can be split between the two batteries, so 2 × 3.7 V 7.1 Ah batteries in series (with step-down regulator) will work, too.

An Arduino is not the best choice for a low power project. More modern processors like e.g. ESP32 can operate at less power. They also offer deep sleep modes with almost no power consumption at all.
Consider also using a dedicated low-power GPS module and activate it only in regular intervalls to save energy.
These measures can strip down the power requirements considerable, consequently a much smaller battery can be used (and thus the weight your pet has to carry around is much less, too).

Assuming you can cut down the average current (mean of powered modes and sleep modes) from 50 mA to 5 mA, a much smaller 1.42 (say 1.5) Ah battery can do the job.

#### mineymoe

Nov 14, 2023
14
Li-ion batteries and using low power devices like ESP32 are definitely the way to go to maximize battery life. Might also be worth spending some time optimizing your code and circuits to reduce power usage even further.

#### Bluejets

Oct 5, 2014
6,863
As #3 says, one can optimise the code used or even put the whole system to sleep if not permanently required to do certain things.
That is dependant on your code and what you require though and that is all in your head.

#### jobitjoseph1

Jul 30, 2021
5
Lithium batteries are the to-go type in today's world.

Let's calculate the required capacity:
7 days = 7 × 24 h = 168 h
168 h × 0.05 A = 8.4 Ah @5 V- minimum!
Let's assume you use a lithium battery with a step-up regulator to get the 5 V you need.
5 V × 8.4 Ah = 42 Wh.
Assuming an efficiency of the step-up converter of 80 % the true required capacity is 42 Wh / 0.8 = 52.5 Wh minimum.
A lithium battery operates at ~ 3.7 V, so the required capacity is 52.5 Wh / 3.7 V = 14.2 Ah

So you would need a 3.7 V 14.2 Ah lithium battery.
Alternatively you could use 2 Li batteries in series (7.4 V) and a step down regulator. The total capacity is the same, but can be split between the two batteries, so 2 × 3.7 V 7.1 Ah batteries in series (with step-down regulator) will work, too.

An Arduino is not the best choice for a low power project. More modern processors like e.g. ESP32 can operate at less power. They also offer deep sleep modes with almost no power consumption at all.
Consider also using a dedicated low-power GPS module and activate it only in regular intervalls to save energy.
These measures can strip down the power requirements considerable, consequently a much smaller battery can be used (and thus the weight your pet has to carry around is much less, too).

Assuming you can cut down the average current (mean of powered modes and sleep modes) from 50 mA to 5 mA, a much smaller 1.42 (say 1.5) Ah battery can do the job.
Thank you I used a 7.4V lion battery pack (2 cell series) and used a voltage regulator to get 5V. My project works as expected now thank you all

#### danadak

Feb 19, 2021
725
You will see when ESP32 is transmitting WiFi signals power is quite high,
so you use it more like a beacon mode where most of the time its in
sleep and wakes up periodically to transmit status. Then average power
can be quite low. Note ESP32 takes time to wakeup, so consult ap notes
on low power operation. Note ESP8266 in these ap notes predecessor to
ESP32, its lower cost, still quite usable for this application.

Note an interesting way to program these parts is Tuniot, a block language IDE.
Setting up a WiFi client or server quite simple. An example of its use -

Choose template, 3rd icon
from right, for examples -

Regards, Dana.

Last edited:

#### Martaine2005

May 12, 2015
4,903
To both @danadak and @bertus .
You both post the most amazing websites, tutorials and linked information.
I thank you both.

#### thom3s

Feb 20, 2024
4
Lithium batteries are the to-go type in today's world.

Let's calculate the required capacity:
7 days = 7 × 24 h = 168 h
168 h × 0.05 A = 8.4 Ah @5 V- minimum!
Let's assume you use a lithium battery with a step-up regulator to get the 5 V you need.
5 V × 8.4 Ah = 42 Wh.
Assuming an efficiency of the step-up converter of 80 % the true required capacity is 42 Wh / 0.8 = 52.5 Wh minimum.
A lithium battery operates at ~ 3.7 V, so the required capacity is 52.5 Wh / 3.7 V = 14.2 Ah

So you would need a 3.7 V 14.2 Ah lithium battery.
Alternatively you could use 2 Li batteries in series (7.4 V) and a step down regulator. The total capacity is the same, but can be split between the two batteries, so 2 × 3.7 V 7.1 Ah batteries in series (with step-down regulator) will work, too.

An Arduino is not the best choice for a low power project. More modern processors like e.g. ESP32 can operate at less power. They also offer deep sleep modes with almost no power consumption at all.
Consider also using a dedicated low-power GPS module and activate it only in regular intervalls to save energy.
These measures can strip down the power requirements considerable, consequently a much smaller battery can be used (and thus the weight your pet has to carry around is much less, too).

Assuming you can cut down the average current (mean of powered modes and sleep modes) from 50 mA to 5 mA, a much smaller 1.42 (say 1.5) Ah battery can do the job.
This is a very detailed and helpful answer. I appreciate how you explained how you came up with the answer, including calculations and assumptions. I learned a lot from your answer.

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