Hello,
I have received my battery (12000mAh, Input: 5-12VDC)
so I worked a bit on my project this weekend.
2 solutions to charge it:
1) buy two 6V 3.4W solar panel (550mA each), wire them to get max 1,1A@6VDC on sunny day and plug directly on the battery and it should work properly.
2) buy a 12V 20W solar panel:
Open Circuit Voltage: 21.4V
Short Circuit Current: 1.32A
Power Allowance Range: 5%
Max Power Voltage: 16.94V
Max System Current: 1.18A
Max System Voltage: 300VDC
Number of Cells: 36 with this solution I need a 'buck converter' to lower the voltage to 12VDC.
After some research I find out that a circuit based on a LM317T voltage regulator can help me.
It can handle max 1,5A with an input voltage from 1,5V to 36V.
If I use this solar panel as source power:
Vi is between 12V (nominal) to 16,94V (max)
Ci is between 0A (night) to 1,18A (max)
so (17V-12V )* 1,18 = 6W to dissipate, correct?
Vo will be 12V
Co will be 0A - 1,18A
I understand that this kind of regulator need an input voltage at least +3V than the output voltage so in my case 12V+3V=15V.
So I should better use a low dropout regulator?
http://www.linear.com/product/LT1086What do you think?