I need to be able to charge a 2v 7amp battery with a solar panel. I understand that the charge controller will keep the battery from over charging/discharging, but what I don't understand is the amps.The solar panel is rated at 5watts.The solar panel comes with a 2v 3amp charge controller but will I need to buy a 7amp charge controller and replace it with that for my battery pack? Please explain. Thanks in advance.
In digital circuitry almst anything is viable. Virtually. The changing of voltages and currents is most of the time viable however not constantly effective. Sure it is extremely easy to make use of the 24 volt energy panel to charge a 2V financial institution, offered that the 24 volt supply has the fundamental current potential to hande the load.
The battery is probably 2v 7amp-hour, not 7 amp. 7amp-hour is basically just how big the battery is. You can charge that battery with as little current as you want, it'll just take longer. The 7 amp-hour tells you that it'll take a long time to charge. 7 amp-hour means it can discharge 7 amps for hour. If you were charging it at 7 amps, it would take hours to charge, but I don't recommend that. You could charge it at .5 amps for 4 hours or .25 amps for 28 hours. The smaller the current, the longer it will take, but it will get there eventually assuming your voltage is high enough (which it should be with the charge controller).
7 Amp Solar Charge Controller
If it is a charge controller that is wired between the panel and the battery only, then a 3A rating is ample. The controller only has to handle the maximum current that the solar panel can output. The panel will have (or needs to have) an open-circuit voltage that is greater than about 4V in order to actually charge the battery, whose terminal voltage will rise above 2V as it charges. The panel's open circuit output voltage typically is about 7V. The 5W rating is at the maximum power point under the illumination of standard sun and at a specified temperature. That maximum power point probably is around 4V, which means the panel will deliver the following amperage to charge the battery: I = P/V = 5W/4V = 0.36A Since 0.36A is well below the 3A rating of the controller, the controller will not be overloaded when charging the battery. Some charge controllers also have terminals for connecting the load that you want to power. If that's the case, then the controller also needs to be rated to handle that load amperage or higher. If you were to connect a 6A load, then you would like to have say a 0A controller. Hope that helps.
