[Thinh Nghiem]

Dear all,

I have an amusing experiment with my smart phone charger. That is, after charging it fully, I connect its input and output toghether, and get surprise result.
Could you see in my youtube clip and give your explanation here

Thanks

Thinh Nghiem

 

[duke37]

There are many amusing ways of b******ing equipment.

 

[OBW0549]

I think the electrons just get tired of going around in circles, and eventually sit down and refuse to participate any further. Then the light goes out.

 

[Thinh Nghiem]

I think the electrons just get tired of going around in circles, and eventually sit down and refuse to participate any further. Then the light goes out.

Very funny explanation

 

[HellasTechn]

If power losses where 0 then the charge-discharge cycle would have kept going on for ever.

I remember when i was a kid i placed a LED lamp connected to a solar panel removed from a calculator just in front of it, thinking that once some light hit the panel then the led will glow and the light from the led would produce current through the panel and so on...

 

[OBW0549]

Very funny explanation

Thank you.

I tried replicating the experiment you described in post #1 with my own USB booster battery. This is what I observed:

1. First, I fully charged the battery and left it on the charger for a couple of hours with the light glowing blue.
2. I then unplugged the battery from its charger and plugged it into itself.
3. The light on the battery came on. At first, it glowed blue.
4. After about a minute, the light began flickering randomly, glowing blue then red then blue again, alternating rapidly back and forth.
5. Over the course of the next minute, the red periods became longer and more frequent, and the blue periods became shorter and less frequent.
6. Finally, the light was red 100% of the time.

What I think is happening here, is this:

These devices have three parts: a lithium ion battery whose voltage ranges from 3.7 volts up to 4.2 volts, a boost converter (a kind of switching regulator) which steps up the battery voltage to 5 volts to feed the output jack, and a charging supervisor circuit which takes the charging input voltage (5 volts) and steps it down in a controlled fashion to provide the charging current according to the lithium battery's recommended four-phase charging profile (trickle charge + high-current charge + constant-voltage phase + periodic top-off charge). The charge controller also operates the blue/red charging status indicator LED. This article describes the charging profile and describes several LiIon battery charger ICs, if you are interested.

The charge controller lights the status LED whenever voltage is present on the unit's charging port. If the lithium ion battery voltage is below about 4.1 volts the light is red, indicating the battery is partially discharged; when the voltage goes above 4.1 volts the light turns blue, indicating that charging is complete and the battery is at full voltage.

Like all other regulator circuits, neither the output boost converter nor the charging regulator are 100% efficient; they both lose some energy (approximately 10% to 30%) in the process of performing their function. So connecting the booster battery's output back to its charging input gradually drains charge from the battery. At first, the battery is fully charged and the indicator light glows blue; then, as the battery voltage begins to drop, it turns red; and finally, when the battery is depleted, it goes out completely.

That's what I think is happening.

 

[hevans1944]

I like your detailed explanation, @OBW0549. I think you nailed exactly what was going on in the video. Now, if we could only get a rational explanation why anyone would do this... investigations in free energy or perpetual motion perhaps? That's not allowed here. But curiosity is, so that's sufficient for me. Interesting post @Thinh Nghiem. Thank you.

 

[hevans1944]

If power losses where 0 then the charge-discharge cycle would have kept going on for ever.

I remember when i was a kid i placed a LED lamp connected to a solar panel removed from a calculator just in front of it, thinking that once some light hit the panel then the led will glow and the light from the led would produce current through the panel and so on...

I am sure (well, pretty sure...) that if you had just added some more LEDs your solar panel would be truly refreshed.

 

[Thinh Nghiem]

Thank you.

I tried replicating the experiment you described in post #1 with my own USB booster battery. This is what I observed:

1. First, I fully charged the battery and left it on the charger for a couple of hours with the light glowing blue.
2. I then unplugged the battery from its charger and plugged it into itself.
3. The light on the battery came on. At first, it glowed blue.
4. After about a minute, the light began flickering randomly, glowing blue then red then blue again, alternating rapidly back and forth.
5. Over the course of the next minute, the red periods became longer and more frequent, and the blue periods became shorter and less frequent.
6. Finally, the light was red 100% of the time.

What I think is happening here, is this:

These devices have three parts: a lithium ion battery whose voltage ranges from 3.7 volts up to 4.2 volts, a boost converter (a kind of switching regulator) which steps up the battery voltage to 5 volts to feed the output jack, and a charging supervisor circuit which takes the charging input voltage (5 volts) and steps it down in a controlled fashion to provide the charging current according to the lithium battery's recommended four-phase charging profile (trickle charge + high-current charge + constant-voltage phase + periodic top-off charge). The charge controller also operates the blue/red charging status indicator LED. This article describes the charging profile and describes several LiIon battery charger ICs, if you are interested.

The charge controller lights the status LED whenever voltage is present on the unit's charging port. If the lithium ion battery voltage is below about 4.1 volts the light is red, indicating the battery is partially discharged; when the voltage goes above 4.1 volts the light turns blue, indicating that charging is complete and the battery is at full voltage.

Like all other regulator circuits, neither the output boost converter nor the charging regulator are 100% efficient; they both lose some energy (approximately 10% to 30%) in the process of performing their function. So connecting the booster battery's output back to its charging input gradually drains charge from the battery. At first, the battery is fully charged and the indicator light glows blue; then, as the battery voltage begins to drop, it turns red; and finally, when the battery is depleted, it goes out completely.

That's what I think is happening.

Great,

My device turns red IMMEDIATELY when it is plugged into itself. And it is dimmed finally