You are probably aware that any electric battery has at least two terminals.
By means of two contacts or wires batteries provide a pathway for the electrons to travel,
and thus deliver power to the circuit.
And whether we had to run an electric motor or light a bulb, all we need to do is attach
the load to the battery output pins with the help of at least two wires.
This simple two wire rule naturally works for all electric appliancies, including home
elecronics, cigarette lighter adapters, and also cell phones.
In fact, mobiles use regular DC batteries that you can use to power any load, provided
it has the matching voltage rating.
In most cases, the positive and negative terminals are on the sides of the battery connector.
However, if we look closely at any smartphone battery, we will notice that there is an extra
3rd connective pad in the middle, and some batteries – like this one – have more
than 3.
What is the purpose of these extra pins?
Let us conduct a simple experiment.
We are going to use two jump wires to feed DC current to this mobile phone from its original
battery.
Gotta take note of connector polarity...
As you may guess, we will not be connecting the middle pin at this time...
Voila!...
As you can see, the phone attempted to start, but then shut itself down...
Just to make sure...
The phone IS working if the battery is inserted the regular way.
So, what just happened there?
Now, there's a whole conspiracy spreading online about the battery's 3rd terminal.
Most people are positive there is some kind of sophisticated circuitry inside the battery
that allows the phone to recognize it, and also ensures the consumer buys only original
batteries, thus protecting the interests of the manufacturer.
But is it really the case?
Let me show you something...
I will put my multimeter into resistance mode... and... the circuit between the negative battery
terminal and the mysterious middle pins measures 8.5k...
As we can see now, the resistance dropped to 8.1k...
And now to 7.7k!
Hold on, I'll show you something else.
This battery comes from the freezer.
And the resistance is 15k.
What we have just observed is the change of resistance, resulting from a change of battery
temperature.
Resistance is probably the most basic concept in electronics, and a resistor is the simplest
and cheapest electronic component.
I believe, now you can guess what's going on here.
The 3rd terminal is the output of the temperature sensor, a thermistor, which is a special type
of resistor whose resistance is strongly dependent on temperature, and it is mounted inside the
battery.
And, it's quite easy to fool the phone into thinking that's it's actually connected to
a real battery by attaching a regular resistor between the ground and the middle pin.
In fact, using this method, you can even run your mobile from an external power supply
without a battery.
So, what is the purpose of this temperature sensor?
The thing is, Lithium-Ion batteries used in all modern appliances, including electric
cars, are actually dangerous.
They can catch fire and explode.
But that only happens if the battery overheats.
Overheating can occur in two cases: if the battery is overloaded or shorted, or during
the charging process.
Since lithium-ion is the best battery technology avaialble to the day, engineers have taken
all precautions to make sure they can be used safely.
Original batteries always have a temperature sensor and also a short-circuit protection
board that cuts power in case of overcurrent.
Most mobile batteries will shut off if current goes above 5A.
Unfotunately, Chinese manufacturers often ignore this rule – as you can see, this
battery does not react to change of temperature.
The reason is simple, its logic board has a regular resistor instead of a temperature
sensor.
And this one does not react to overcurrent – which, in fact, is much worse, since it
actually CAN catch fire if you short it.
Many online marketplaces sell batteries that have no protection.
The reason this danger is so overlooked and they are so widespread is because short-circuit
rarely occures in real life.
Several conditions must match for this to actually happen.
But after watching this video, I would never buy a 3rd party battery...
At least if I were you.
That's all for today folks, this was Ron Mattino.
If you like this video, please comment share and subscribe... and...
I will see you later.