I am building some solar panels from 6" cells (4W, 0.5V, 8A). At the moment I have two 1x2 panels and one 2x2 panel. So there are 8 cells in all panels and the added voltage is up to 4V.
Now I want to store the energy somewhere. I have a laptop with the input of 19V DC 2.1A (40W) and I'm also planning to buy a 12V 12Ah battery. As far as I know if I will provide voltage that is too high/low for the laptop/battery, it may cause some problems or even damage, so I need to control the voltage. But what about the current? What happens if I provide a current that is too high/low for the battery/laptop (since there are many models out there, I'm asking about usual situations if there are such)?
So I need to control the voltage and I assume that I also need to control the current. Since I'm on a low budget and have lots of time, I decided to build my own voltage/current controler circuits (one for the laptop and one for the battery). When building a controller for my laptop, it's pretty clear (?) that I have to provide 19V DC 2.1A. But what about the 12V battery? The only parameters given on the battery is 12V and 12Ah (in the catalogue of the shop that i'm going to buy it in), so what input current should I provide for that battery?
I want the circuits to be as simple as possible, with less components, since my knowledge in electronics is very narrow (for now). I would appreciate if you would give me advice, links to information or even suggest your own circuits for this application.