Solar Mobile Phone Charger

[miaomiaooh]

I use the solar panel which the voltage is 5v & current is 300mA, then i use the voltage regulator LM7805 to make the output voltage is 5v and current is around 300mA, then shall i need add the capacitor or other component in the circuit? & wat the value ? can use the normal AA rechargeable battery as the energy storage part??

 

[akg]

the 7805 requires atleast 8v i/p to work properly , ref its datasheet

 

[miaomiaooh]

so, wat component i suitable use to apply in the solar cell phone charger??
& the solar panel output current & voltage is around 5v & 300mA

 

[audioguru]

If your solar panel is rated at 300mA then it is when it is pointing directly at the sun at noon. Its current will be much less as the sun moves and as the sun is at an angle during most of the day.

Why do you have a voltage regulator? The charger for your mobile phone might be an entire charging circuit, not just a regulated power supply.
Different battery chemistry requires different charging methods to avoid a fire and to let the battery last a long time. Which type of battery is in your mobile phone? Ni-Cad, Ni-MH or Lithium?
Why do you have a rechargable AA cell?

 

[miaomiaooh]

If your solar panel is rated at 300mA then it is when it is pointing directly at the sun at noon. Its current will be much less as the sun moves and as the sun is at an angle during most of the day.

Why do you have a voltage regulator? The charger for your mobile phone might be an entire charging circuit, not just a regulated power supply.
Different battery chemistry requires different charging methods to avoid a fire and to let the battery last a long time. Which type of battery is in your mobile phone? Ni-Cad, Ni-MH or Lithium?
Why do you have a rechargable AA cell?

using the GP Ni-MH 1300mA rechargeable battery x 4 as the energy storage,
so cannot directly charge the battery??

 

[audioguru]

Four Ni-MH cells need a voltage of at least 5.4V from a charger. Your solar panel will have 5.4V or more with at least 200mA for only about 2 hours each day. The 1300mA/hr cells need about 1800mA/hrs to fully charge. Therefore the battery will take about 4.5 days or more of perfect weather to fully charge.
What current does the phone use for standby and how much for talking?
How many hours a day is the phone being used for calls?
Is the phone on standby for the remainder of 24 hours or if it is turned off each night, for how long is it turned off?

 

[miaomiaooh]

Four Ni-MH cells need a voltage of at least 5.4V from a charger. Your solar panel will have 5.4V or more with at least 200mA for only about 2 hours each day. The 1300mA/hr cells need about 1800mA/hrs to fully charge. Therefore the battery will take about 4.5 days or more of perfect weather to fully charge.
What current does the phone use for standby and how much for talking?
How many hours a day is the phone being used for calls?
Is the phone on standby for the remainder of 24 hours or if it is turned off each night, for how long is it turned off?

y i use the NiMH cells to connect the phone, the voltage & current of the NiMH cells will suddenly drop ( 3.xx volt drop to 1.xx volt )??
have any component can hold the voltage or current, dun let it decrease...
so, if i directly use the solar panel and a diod to connect the NiMH cells, will it successful charge??
thx you!

 

[audioguru]

Each fully charged Ni-MH cell will reach 1.35V while still charging. They will each be 1.2V or 1.25V for a small current while supplying current to a load. So the four in series will measure 4.8V to 5.0V while discharging.

With a series diode to prevent the battery from discharging into the solar panel at night, there won't be enough voltage to charge 4 cells.

 

[miaomiaooh]

Each fully charged Ni-MH cell will reach 1.35V while still charging. They will each be 1.2V or 1.25V for a small current while supplying current to a load. So the four in series will measure 4.8V to 5.0V while discharging.

With a series diode to prevent the battery from discharging into the solar panel at night, there won't be enough voltage to charge 4 cells.

yesterday ,i measure the original nokia charger by no load charging,the digital multimeter show 9v & 0.6A.
then i use a lead acid rechargeable battery(6v,1.3AH) to charge the nokia cell phone (just connect to the cell phone,no place other component),the screen have response but few second show "not charging", so is the voltage or current more lower???
then i place a diode by series connection,the voltage drop many, is the diode drop down the voltage?
the current is charge the battery,so the current more higher, the charging time will more shorter,
then the voltage is for wat??low or high voltage have any impact??

 

[audioguru]

I think you blew-up the charging circuit or wiring in your phone from the massive overcurrent from the lead acid battery. You should have used a resistor in series to limit the current.

How did you measure the current from the Nokia charger? If you just shorted it with the ammeter then you also might have blown-up the charger. You are supposed to measure current with the ammeter in series with the load (the phone with its battery).

 

[Someone Electro]

All phone chargers are just a powersuply some are not even regulated.So meshure the output from your charger at a slight load like 100mA and make somhing that outputs the same voltage.Oh and use a way of limiting the curent like a resistor

Charging electronics are always in the phone.some high curent chargers even have a temperature sesor on the batery to chage it at maximum curent whithout blowing the cell.(The temp sesor in my phone can even be read by software)

 

[miaomiaooh]

All phone chargers are just a powersuply some are not even regulated.So meshure the output from your charger at a slight load like 100mA and make somhing that outputs the same voltage.Oh and use a way of limiting the curent like a resistor

Charging electronics are always in the phone.some high curent chargers even have a temperature sesor on the batery to chage it at maximum curent whithout blowing the cell.(The temp sesor in my phone can even be read by software)

so, if the charging current is over the phone's input current limit, it cannot be charged??

 

[geetha bharadhwaj]

suggestion

hi, friend
i am from india. i heard of solar cells not charger please can u send me the design circuit of that which may help in my projects

 

[geetha bharadhwaj]

please send me that waiting for your reply

 

[audioguru]

Geetha,
A charger is designed for a certain battery. The charger circuit considers if the battery is lead-acid, Ni-Cad or Ni-MH and its voltage and capacity.

Go to the website of a battery manufacturer like Energizer and look at their tutorials on how to use and charge their rechargable batteries.

Go to the website of a semiconductor manufacturer like Maxim-IC and look at their battery charger ICs.

 

[miaomiaooh]

Geetha,
A charger is designed for a certain battery. The charger circuit considers if the battery is lead-acid, Ni-Cad or Ni-MH and its voltage and capacity.

Go to the website of a battery manufacturer like Energizer and look at their tutorials on how to use and charge their rechargable batteries.

Go to the website of a semiconductor manufacturer like Maxim-IC and look at their battery charger ICs.

erm...,so i wan the charge the phone battery,wat website?
i juz now use a yokohama lead acid rechargeable battery to charge a phone battery, the screen show "not charging", at the same time i measure the output voltage is about 5v, but the current is about 1mA, if measure by no load, the output is 0.5A bcoz i place a 10ohm resistor...
y the current drop many??

 

[Thunderchild]

frankly to charge a mobile phone with solar pannels does not sound like a good idea at least not like you want. i would advise you to start by doubling your panel voltage you will need a circuit for this then you need to charge a battery with it. you will need at least 6 volts to charge a phone battery, I did what you did with four AA batteries to creat a backup for my cell phone but it did not charge for long so I used 6 batteries and a 7805 regulator and that was better unfortunately you are going to loose so much power in all these conversions that you are wasting your time you will get like 100 mA average on a sunny day and that is 800 mA a day if you are lucky my mobile phone is 1400 mA. I too have solar pannels but am not dreaming of using them like this even though it would be good because my phone is ouside fixed to my bacolny railings so it will pick up the UMTS signal for a fast internet connection. I am keeping it undercharge with a 12 V lead acid battery and am thinking or wiring up a car bettery so it will run for weeks and keep the battery in use. hopefully some time I will make some kind of a switching converter because 12-4.5 = 7.5 volts wasted. you probably best make and automatic light circuit with your solar pannels or get more pannels and a good power system

 

[audioguru]

I told you already why your 4 Ni-MH cells don't charge: "Four Ni-MH cells need a voltage of at least 5.4V from a charger." You shouldn't charge a battery from a voltage source, you should use a current source that has a voltage that is high enough.

 

[Thunderchild]

he sounds very confused to me and best not meddling with this stuff best to just make an automatic night light or get more solar pannels

 

[miaomiaooh]

I told you already why your 4 Ni-MH cells don't charge: "Four Ni-MH cells need a voltage of at least 5.4V from a charger." You shouldn't charge a battery from a voltage source, you should use a current source that has a voltage that is high enough.

thx for ur teaching,so which battery i suitable to use??