[Moved]Mobile phone charger

[Ivan10]

Hello!

Im developing mobile phone charger for myself and I have done it but works not correctly

https://obrazki.elektroda.pl/9353432000_1409391370.jpg

I have rechargable 1000 mA/h 3.7V Li-Pol Battery with 1.5A max pulse current and 3.0V cut-off voltage
And I have to supply 5V+-0.1V load with up to 2.4A current
I decided to use cirrent limited IC with step-up converter to have 5V+-0.1V with 0.75A on output
As result I have got breakdown pulses on output when load on and when load increase the current and also when battery become discharged
Please do an advise how to get stabilized 5V+-0.1V with 0.75A on output when supplying up to 2.4A 5V load

Thanks in advance

 

[BradtheRad]

I have rechargable 1000 mA/h 3.7V Li-Pol Battery with 1.5A max pulse current and 3.0V cut-off voltage
And I have to supply 5V+-0.1V load with up to 2.4A current
I decided to use cirrent limited IC with step-up converter to have 5V+-0.1V with 0.75A on output

Assuming I get the right picture...

Your boost converter (left half of your schematic) needs to draw that entire 1.5A at 3.7V, to step it up to 5V at .75A.

Watts out can never be more than watts in.

Then if you attach a 2.5A load, it will drag down the battery voltage, disrupting operation.

 

[Ivan10]

Assuming I get the right picture...

Your boost converter (left half of your schematic) needs to draw that entire 1.5A at 3.7V, to step it up to 5V at .75A.

Watts out can never be more than watts in.

Then if you attach a 2.5A load, it will drag down the battery voltage, disrupting operation.

Thank you for your support!
I understand that I can give more power that have so I trying to give what I can:
3.7V * 1000 mA = 3.7W
And on output I can have not more than 3.7W, at least 0.6-0.7A * 5V = 3 - 3.5W
I have done it and its charge the phone but with some problems with form of 5V at power transition processes
Can I do stable 5V with 0.6-0.7A current limited to do more longer charging process with 3 - 3.5W power?

 

[Audioguru]

Your battery has a capacity rating of 1000mAh (milli-Amp hours) when it is new. Then it can supply 700mA for 1.4 hours. You must have a circuit detect the reduced voltage from the discharged battery and disconnect the load when the battery voltage drops to about 3.2V.

I do not know if your voltage stepup circuit regulates the output voltage at 5.0V when the input voltage from your battery has dropped to 3.2V.

EDIT: Your Lithium battery is 4.2V when fully charged and 3.2V when it should have its load disconnected. Then its average voltage is 3.7V. 5V at 700mA is 3.5W. 3.7V at 3.5W is a current of 0.95A but the circuit uses more current because it heats a little. Then the battery can charge your 5V/700mA phone for maybe 48 minutes.

 

[Ivan10]

Your battery has a capacity rating of 1000mAh (milli-Amp hours) when it is new. Then it can supply 700mA for 1.4 hours. You must have a circuit detect the reduced voltage from the discharged battery and disconnect the load when the battery voltage drops to about 3.2V.

I do not know if your voltage stepup circuit regulates the output voltage at 5.0V when the input voltage from your battery has dropped to 3.2V.

EDIT: Your Lithium battery is 4.2V when fully charged and 3.2V when it should have its load disconnected. Then its average voltage is 3.7V. 5V at 700mA is 3.5W. 3.7V at 3.5W is a current of 0.95A but the circuit uses more current because it heats a little. Then the battery can charge your 5V/700mA phone for maybe 48 minutes.

Thank you for your support!
Yes I know what, my battery has protected PCB that has cut off voltage at 3.0 V of Battery
and the same protected PCB has max pulse current of 1.5A and short circuit detection to save the battery

 

[Audioguru]

There is a company in China that is making and selling fake Protection circuits for Li-Ion battery cells to battery manufacturers. There is a video of it on you tube but I didn't copy it. The fake circuits are simply useless photos of a protection circuit and look identical to a real circuit.

There are many videos on You Tube showing fake Li-Ion cells that are mostly flour. They have a tiny little 60mAh Li-po battery cell inside.
https://www.youtube.com/watch?v=eOshOXcSkDA

 

[Ivan10]

There is a company in China that is making and selling fake Protection circuits for Li-Ion battery cells to battery manufacturers. There is a video of it on you tube but I didn't copy it. The fake circuits are simply useless photos of a protection circuit and look identical to a real circuit.

There are many videos on You Tube showing fake Li-Ion cells that are mostly flour. They have a tiny little 60mAh Li-po battery cell inside.
https://www.youtube.com/watch?v=eOshOXcSkDA

Thank you for the interesting link, bit Im using and mean 3.7V Li-Pol rechargeable batteries with protected board

 

[betwixt]

What Audioguru is saying is not specific to one battery technology. Just becasue it's 'polymer' and not 'ion' makes no difference, they are both available as genuine articles of course but also both available as fakes. It isn't the battery type that matters, it is where it came from. Only use the manufacturers authorized sales agents to ensure traceability to source. I've seen 'protected boards' built in to battery packs which are nothing but a resistor to make it difficult to tell from outside there isn't something there, even if it doesn't work.

Don't underestimete the number of fakes out there, it is probably not far off the number of real ones.

Brian.

 

[Ivan10]

What Audioguru is saying is not specific to one battery technology. Just becasue it's 'polymer' and not 'ion' makes no difference, they are both available as genuine articles of course but also both available as fakes. It isn't the battery type that matters, it is where it came from. Only use the manufacturers authorized sales agents to ensure traceability to source. I've seen 'protected boards' built in to battery packs which are nothing but a resistor to make it difficult to tell from outside there isn't something there, even if it doesn't work.

Don't underestimete the number of fakes out there, it is probably not far off the number of real ones.

Brian.

Thats an interesting then, - how PC USB port hold 5V within 500 mA output currect when charging the phone???

 

[betwixt]

I'm not sure what relevance that has. A USB port passes 5V from a supply inside the PC which has a much higher current capacity, think of it as an on/off switch with an over-current trip.

Your original question is somwewhat ambiguous, asking for a 5V 0.75A supply that is also a 5V 2.4A supply. If that is what you really need, a 2.4A supply is all you need, the battery charger will only take what it needs up to that limit.

I think what you are getting at is how to make a 5V regulated high current supply out of a 5V low current supply which is not possible. The output power (V x I) can never be more than the input power (V X I) and in fact the input will need to be considerably more to overcome the inefficiencies of the circuit between them. Stepping the input 5V to a higher voltage so you have enough overhead to regulate it down again is also not an efficient method.

Brian.

 

[Audioguru]

I have a small 3.7V/325mAh Li-po battery that is rated at 65C (21.1A). Its maximum pulse current is 42.2A. It does not have a protection circuit.
Your 1000mAh battery is much larger than mine but its maximum pulse current is very low at only 1.5A. Why?

When your weak battery drives a voltage stepup circuit then it should be able to power the charger in your phone continuously with 5V at an average current of 800mA for 1 hour.

Why not buy a more powerful "power bank" for only $9.99US?

 

[Ivan10]

I have a small 3.7V/325mAh Li-po battery that is rated at 65C (21.1A). Its maximum pulse current is 42.2A. It does not have a protection circuit.
Your 1000mAh battery is much larger than mine but its maximum pulse current is very low at only 1.5A. Why?

When your weak battery drives a voltage stepup circuit then it should be able to power the charger in your phone continuously with 5V at an average current of 800mA for 1 hour.

Why not buy a more powerful "power bank" for only $9.99US?

Thank you very much, I understand you but I tried to order BAT that do not emit any heat during charging phone