How To Measure Internal Resistance Of A Battery Using Multimeter

Batteries are institute and used everywhere! Everyone has seen them and used a battery before. In another previous commodity – What happens in an electric circuit: Voltage vs Current, we defined and explained what is voltage, current and resistance. Withal, do you know that every battery has its own opposition to the flow of the current? This is known equally Internal Resistance.

Nosotros talked virtually resistance – resistance refers to the measure of opposition to the flow of electric current. Internal Resistance is essentially an opposition to the menstruation currently offered by the cells and batteries themselves. In this article, we will be talking nigh how to measure the internal resistance of a battery:

What is internal resistance?
How to measure out internal resistance?
Recommended tools and products to help y'all.

What is Internal Resistance?

Source: hk-phy

Every bit mentioned, internal resistance refers to the opposition to the flow of current offered by the cells and batteries themselves. All materials resist current flow to some degree, even cells and batteries. This is due to the materials that are used to make the batteries.

The elements that make up a typical battery includes zinc, carbon, lithium, mercury, silver and etc. All of them are not a perfect conductor of electricity. Therefore, it will be difficult to find a battery with nil internal resistance, probably even incommunicable.

Internal resistance can be seen as the gatekeeper of a battery. Lower resistance means lesser restriction. If there is high resistance, the battery will rut up and voltage volition driblet.

How Internal Resistance affects Voltage and Electric current?

To understand this better, let's apply Ohm's Law. Ohm's constabulary is a formula dictating the human relationship betwixt voltage, current and resistance in a excursion. Ohm's Police force states that V=IR. 5 refers to the Voltage, I refers to the Current and R refers to the Resistance, in our case, the internal resistance.

The key betoken to empathize is that Voltage and Internal resistance is an independent variable, the main thing that is affected is the dependent variable, i.due east. the Current. When the internal resistance increase, by 5/R=I, the current decreases. When the internal resistance is lower, vice versa, the current increases. They are inversely proportional. However, all of these is only based on the Ohm'south Law formula.

In the real world, Voltage decreases when internal resistance increases. That is also how we tin measure the internal resistance of a battery.

In a nutshell,

Internal Resistance is a resistance in the circuit that is from the cell or battery itself. With higher internal resistance, current and voltage will exist lower.

With that in mind, allow'south at present explore why should we measure internal resistance?

How to measure Internal Resistance?

What yous will need:

A new Battery (AA Battery)

A Voltmeter

0.28 Inch LED digital DC voltmeter – Yellow

A Resistor

RESK – Resistor Kit

Steps:

Wire up your Battery and Voltmeter in the following configuration.

[Ignore the Triangle (GND) on the bottom-left]

Take down the measurements from the voltmeter. one.500V

The voltmeter should bear witness the amount of voltage with regards to your battery specification. This is due to no load existence connected to the circuit. This is also known as the open-excursion voltage (VOC).

Open-excursion voltage (VOC) is the voltage when it is not connected to any load in the circuit.

Wire upwardly your Battery, Voltmeter, and Resistor in this configuration.

[Ignore the Triangle (GND) on the bottom-left]

In our case, we will be using a 4-ohm resistor.

Have downwardly the measurements with the voltmeter. 1.446V

The voltmeter should show a lower voltage value. The drop in voltage is caused by the internal resistance of the bombardment. We tin calculate the internal resistance if we have the readings of the open-circuit voltage (VOC) and the voltage beyond the bombardment with a load, which is a four-ohm resistor in our instance, attached.

Use the Ohm's Constabulary formula and Kirchhoff's Voltage Police formula to summate the Internal Resistance.

Nosotros will get-go plug in the value nosotros receive into Ohm's Police to determine the current flowing through the excursion.

Abbreviation:

V = Voltage

I = Current

R = Resistance

VL = Loaded Voltage

RL = Resistor Value

5 = I · R

VL = I · RL

1.446V = I · 4Ω

I = 1.446V 4Ω

I = 0.3615A

We will then use Kirchhoff's Voltage Law to determine the voltage across the internal resistor in the bombardment. This value is likewise the voltage drop beyond the internal resistor.

Abridgement:

VOC = Open-excursion Voltage

VI = Voltage across Internal Resistor

VL = Loaded Voltage

VOC = VI + VL

1.500V = Half dozen + 1.446V

VI = 1.500 – 1.446V

VI = 0.054

Now, we have the value of the voltage drop across the internal resistor, and the current that's flowing through the excursion. We tin can now utilize Ohm'due south Police force again to find the Internal Resistance of the Bombardment.

Abbreviation

VI = Voltage beyond Internal Resistor

I = Electric current

RI = Internal Resistance

Vi = I · RI

0.054V = 0.3615A · RI

RI = 0.149Ω

From this, nosotros can encounter the internal resistance of the AA battery is 0.149Ω!

Recommended Tools and Products

I hope you've learnt how to measure the internal resistance of a battery and too how and when to apply information technology! Here are some bombardment related tools and products which can assistance you with your IoT projects!

UPS Module for Raspberry Pi Pico – Uninterruptible Power Supply

This Uninterruptible Power Supply (UPS) is a module designed to keep your Raspberry Pi Pico running with a Li-ion battery. It too comes with a voltage/current monitoring chip and a battery status indicator.

Features

Standard Raspberry Pi Pico header
Li-ion battery compatibility with dynamic power pats direction for a stable power supply
I2C bus communication to monitor battery voltage, current, power and the remaining capacity
Several Battery Protection Measures i.e. overcharge/belch protection, over electric current protection, brusque circuit protection, opposite protection, and equalizing charge characteristic
Onboard charging, power and battery warning indicator

0.28 Inch LED digital DC voltmeter

This is a supermini 0.28inch LED display. Exercise not be deceived past its small-scale exterior, information technology comes with a reverse connect protection characteristic. This voltmeter can be used to measure out mobile telephone battery, car bombardment, and other such applications. There are several colours available too: Yellowish, Red, Dark-green, and Bluish.

Specification

Voltage Range: 2.5 – 30V
Work Current <30mA
Size: thirty×xi.seven×9.two mm
Measure speed: 200ms/one time
Accuracy 3%

18650 Battery Holder Case – 2 Slot with Switch

This is a battery instance for your 18650 rechargeable batteries! This battery holder case can fit two 18650 rechargeable batteries, and it comes with a built-in switch. At that place are wire leads integrated into the instance for soldering/connecting to your IoT projects!

18650 Bombardment Holder Case – iv Slot

This is a 4-slot battery case for your 18650 rechargeable batteries! This case tin fit four 18650 rechargeable batteries. Similarly to the same battery holder instance, there are wire leads integrated into the case for soldering/connecting to your IoT projects!

Summary

I hope you learnt more nearly measuring the internal resistance of batteries. It can be a fun project for you to try out if y'all're new to building circuits. If you accept whatever questions, feel gratuitous to leave them in the annotate downwards beneath!