[SOLVED] Solar power phone charger

[navienavnav]

I have a setup of 4 solar panels in parallel which, under direct sunlight yields the following result :

Open-terminal voltage : 5.6 to 6 V
Current with terminals shorted through multimeter : 0.9 to 1.1 A


When I directly use the solar panels to charge the phone, the charging current on the phone (though an android app) is showed to be around 150mA. Needless to say, this is very poor and doesn't even charge the phone considerably.

When charging from the wall charger, the app shows the current to be around 500 to 600 ma and when through USB, it shows it to be 300 to 360 mA.

So, I thought that maybe the shorted terminal current for the solar panel setup should have been much higher for it to be a practical solution. So I did this test :

I cut a USB cable halfway(which was lying around) to expose its wires and then using a multimeter, measured its open terminal voltage (the + and - pins) and then shorted them through the multimeter while connected to the aforementioned wall charger to measure the current. These were the readings :

Open-terminal voltage : 5.21 V
Current with terminals shorted through multimeter: 0.92 A


Now, this has confused me. According to this data, my solar panel setup should be powerful enough to charge the phone.


What I've already tried with no success:

-> Shorting the Data+ and Data- pins.
-> Putting a resistance of nearly 200 Ohms between the data pins.


I think it might have to do with some sort of switched mode power supply kind of a thing working here. Is it so? And if it is so, then does "SMPS" method works while charging from USB too?

Do I need any additional circuit to properly utilize the power provided by the solar panel?

Please help

 

[Usama Siddiqui]

Re: Need help with solar powered mobile charger...please see!!

when you are shorting it directly with the multimeter it shows the maximun current rating as due to maximum potential difference,what happens is that when u charge a phone there is a potential in battery which actually lowers the potential difference between your battery and the charging source therefore it reduces the current,what a charger mostly consists of is a darlington pair configuration to increase the current. i suppose u need to make a small circuit of that it will do your job quite fine .

 

[navienavnav]

Re: Need help with solar powered mobile charger...please see!!

when you are shorting it directly with the multimeter it shows the maximun current rating as due to maximum potential difference,what happens is that when u charge a phone there is a potential in battery which actually lowers the potential difference between your battery and the charging source therefore it reduces the current,what a charger mostly consists of is a darlington pair configuration to increase the current. i suppose u need to make a small circuit of that it will do your job quite fine .

hello! Thanks for your response .....I am not sure if that makes much sense to me.

Darlington pair can surely increase the current but where will it get its energy from? It could multiply the current in accordance to the total current gain of the pair but doesn't it itself need electrical power to do that? So hoe does it serve our purpose?

 

[Usama Siddiqui]

Re: Need help with solar powered mobile charger...please see!!

i thought you said that you were using a solar panel ,arent you using it?????

 

[navienavnav]

Re: Need help with solar powered mobile charger...please see!!

Yes, I am using it. But how do I use the solar panel to BOTH drive the load (that is the phone) and also provide the base current? What purpose will that serve?

 

[Usama Siddiqui]

Re: Need help with solar powered mobile charger...please see!!

no you will certainly not drive both things together,you'd havto place the darlington circuitry between solar panels and the phone,the problem is that your phone aint geting the proper current to get the job done on time?? right?,so you'd place it before the the phone...

 

[navienavnav]

Re: Need help with solar powered mobile charger...please see!!

Hmm... and how shall that be done? If I am using Darlington pair such that solar panel serve serve as the source of energy that will be used to create the load current, then what will drive the base of the darling ton pair?

 

[Usama Siddiqui]

Re: Need help with solar powered mobile charger...please see!!

ohhh now i get your issue,i'v kept repeating that darlington circuitry,basically how can darlington be used independently???? thats not how its done, you'd havto make a simple differential pair(where you'd provide the input) the single ended output is fed to darlington pair and from there to your cell phone .

 

[navienavnav]

Re: Need help with solar powered mobile charger...please see!!

Same issue persisted with my Solar Powered AA and AAA Battery Charger. But finally fixed.

And how did you fix it? Pray tell us.

 

[navienavnav]

Re: Need help with solar powered mobile charger...please see!!

I had bought 2600mAH solar panel powered battery bank off ebay and it arrived today. I just now tried charging my phone with it. Funny thing is that the android app now shows the charging current to be around 100 to 140 mA but the mobile IS getting charged and the charge percentage IS rising. On the other hand, when I try to charge the cell phone with my solar panel setup which is obviously much more stronger than the 0.4 W solar panel in this gadget yet my phone shows charging and the charge percentage keeps on decreasing.

This is giving me a headache. What is this? Is it because the phone charger a constant current source? If not then what is it?

 

[navienavnav]

Re: Need help with solar powered mobile charger...please see!!

Same issue persisted with my Solar Powered AA and AAA Battery Charger. But finally fixed.

Still waiting for your solutionnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn :S

 

[navienavnav]

Re: Need help with solar powered mobile charger...please see!!

Just an update, quite surprisingly, my new cellphone charges just fine and as expected with the same solar panel setup. I don't know why why previous Xperia acted so odd with the same setup.

 

[Usama Siddiqui]

Re: Need help with solar powered mobile charger...please see!!

due to the sameeeeeee reason,the current that sony Xperia needs isnt provided my the solar panel, but since ur new phone might have needed just the amount of current the solar panel produces dats y it works fine with it. if not satisfied,try to check some nokia chargersss all would be of the same pin and voltage(around 5) but would be having different current rating.