I want to also know if the 0 watt rating on the solar panel is 0 watts per day or is it constantly adding 0 watts? Is there a time which the 0 watts is being added like 0 watts per second or 0 watts per minute and so on?
You need more panel because it will take more than ones worth of sunshine to charge this battery so the battery will need to sit over night and wait to continue the charge. clouds will make the problem even worse. I use 24 - 00 Ah batteries with a 3500 watt system and I am using a 48 volt system. So my Ah = 24 X 00 / 4 = 600 Ah but this is at 48 volt so the watt hours are the same. But My computer puts the power where it is needed automatically. You have 25 watts for at best 0 hours per day = 250 Watt hours per day. That battery needs at least 200 x 2 = 2400 watt hours that does not take efficiency of any of the systems into account. As you can see this battery may never charge completely.
0 Watt Solar Battery Charger
What is the open circuit voltage and voltage under load with the panel in full sun? Assuming it is typical of many 0W panels, the open circuit voltage is 2V and the voltage under load is about 7V. 0W/7V is 588mA. A typical car battery is 40 Amp Hours. Amp Hours, or Ah, is the capacity of the battery. How much current a battery can delivery starting a car is called cold cranking amps. A deep cycle marine battery will typically be more than 40Ah. A 40Ah car battery at 50% charge will more than likely start your car in fair weather. Cold weather is another story. So, to get a completely dead car battery to 50% - 20Ah - would be maybe two days of full sunlight - with only a 50% charge, or about 2.2 Volts. Not a great battery charger - however - It makes a great supplement, and can offset the use of DC powered equipment in the vehicle while the engine is off. Things like low-wattage lights, cell phone chargers, tablets, and the like will drain the battery down that much slower. I have a number of powered but low current items on in my truck all the time. A panel helps offset some of that drain if I don't drive for a few days.
a 0w solar panel means at peak efficiency ( high noon, panel pointed flat at the sun, hitting it at 90 degrees), you will get 0 watts (at any given second). Watts = volts x amps a 2volt battery needs an incoming current of at least 3 volts to charge it; 3.5 volts is better. so if the output VOLTAGE of the panel is less than 3 volts it wont do anything. Even if it is, 0 / 3.5 = .74 amp.( three quarters). It will take forever and a day to charge a deeply discharged deep cycle battery.......... consider that a small 0v battery charger is putting out 3-5 amps ( or 3 x 0 =330 Watts) and the alternator on a car is putting out 20 to 50 amps at 4 volts ( 280 to 730 Watts).
