Since the 10W solar panel delivers only 0.8A in full sun, the charge controller is overkill, and may be inefficient, say only 50%. To fully charge the 7Ah battery, it is going to take >(7/0.5)/0.8 = 17.5 h of bright sun.
The efficiency of the MC34063 down-converter is likely ~75%. The efficiency of the charging process inside the cell phone is likely to be ~80%, too. To get 1.2Ah into the cell phone, you will likely need (1.2/0.8)/0.75 = 2Ah out of the battery, so only about three full recharges...
Doesn't a device that expects charging via USB want only 5.0V?
If it was me, I would have used a 6V SLA.
AFAIK, the OP was planning to just supply 5V to the cell ph0ne and let the internal charger take care of it.DO NOT EVER charge a 3.7V Lithium battery from 5V because it might blow up and might catch on fire.
The cell phone has a Lithium battery charger circuit inside that has a 5V input and its output properly charges the 3.7V Lithium battery then turns off when it detects a full charge.
I mentioned it because he talked about his "MOBILE PHONE ( 3.7v 1200mah)" which sounds like the spec's for his battery.AFAIK, the OP was planning to just supply 5V to the cell ph0ne and let the internal charger take care of it.
I mentioned it because he talked about his "MOBILE PHONE ( 3.7v 1200mah)" which sounds like the spec's for his battery.
mike i didnt just left you. i will be back wen i finish reading those links that u provided me okAFAIK, the OP was planning to just supply 5V to the cell ph0ne and let the internal charger take care of it.
Why do you want to use an interim battery? It is possible to charge your phone directly from the solar panel using simple controller.
Lead-Acid batteries are difficult to deal with - you cannot fully discharge it, and you need to make sure it is fully recharged at least once a week. To meet these requirements, you may need a two-stage controller.
I totally agree !
Please take a few extra minutes and write legibly.
I am an old curmudgeon , but I would rather not call in the grammar police or the spelling police .
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When a solar panel is not pointing directly at the sun then its voltage and current are low.
That is why a solar panel moves so that it is always facing the sun.
When a solar panel is shaded then its voltage and current are very low.
That is why a solar panel is never shaded. Also that is why a windmill generator is usually seen beside a solar panel so a battery can be charged even when it is cloudy.
Please (pls?) type in English with proper spelling bro (broken?) so that we wud (wood?) understand wat (watt?) u r (you are?) toking about.
Your phone already has a charger in it.
so all you need to do is provide 5V from the panel. Solar panels act mostly as a current source. A capacitor followed by a voltage converter/regulator should be able to do it.
Of course if you shade the panel, it will not produce anything (may be few percent of nominal). Will also jump up and down as clouds pass by. I don't think it would damage the charger because it must be designed so that you can plug/unplug it at any time. I do it few times a day with my phone, and it's fine.
If you're afraid of voltage sugging, you may need some sort of brown-out protection.
If you're driving, it is much easier to charge the phone from your car.
I know my phone charges in about an hour (a little bit faster, actually). Assuming it uses 70% of battery capacity, this is 1300 mAh x 0.7/1h = 900 mA. So, you should expect the phone charger to need about 1A. This, of course, depends on the phone. So, 500mA may not be enough.
But you can always try this by connecting your 5V regulator to 12V wallwart and measuring the current draw. It'll probably be the highest on severely discharged phone.
On the panel. You need it at least 5V + whatever is the maximum voltage drop on your regulator. 6V might work, but 12V will work better.
If your regulator is a switching one, you need to provide 1A*5V = 5W. With 80% efficiency, it'll give you 6.3W. This is a panel the size of a big book.
If your regulator is liner, you need 1V*12A = 12W. This is quite a big panel.
These numbers are for panel turned directly towars the Sun in ideal conditions.
Most of the time, you probably will need a panel twice as big.
If you want to charge in the cloudy weather, you need a panel about 10 times as big. Just as audioguru said, this is an enormous panel, and probably is not worth the effort. So, I would size the charger for sunny days only.
Your original idea with LA in between would let you slow down the charging, so you would need smaller panel, but then you would need much longer exposure. You would also need to account for losses and inefficiencies in LA.
I don't agree that it is difficult to handle high current from the panel. A capacitor placed accross the panel will take care of it. As the capacitor charges, the voltage will raise and therefore the current from the panel will decrease. When voltage increases to panel's Voc (which is only 20% more than production voltage) , it will be no current at all.
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