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If I bought a rechargeable 4R25 Battery, How many solar cells would I need to keep it charged? ? Answered

I'm building a dog house which the base will be 9-10inches underground, which helps with the build up cool dead air at the base to help keep the house cool. I want to use four(4) computer fans to help ventilate the house from the base where the dead air resides. Near the roof of the dog house will be ventilation holes for the dog, in fact I may use another fan to vent out the hot air. I was hoping that I could use some silicone cells to keep the battery charged, but not sure how many I would need to keep it charged. if it requires too many I may stick with recharging the battery in the house or using a 9v battery for each fan and swapping it out here and there.



7 years ago

probably 3-4 120mm fans computer case fans to be precise

The number of cells it takes to KEEP it charged depends on the load you impose on it ! How much current will the fans use ? How often will they run ?

I'd say a 4R25 just won't hack it, with the load you are describing.


You can always do a trickle charge application. Just remember to put a diode in series with the solar panels somewhere. (Otherwise, you battery will lose its energy through the solar cells at night.) You can always overcharge the battery and make it corrode. I'd start with only a few cheap panels and add more if you see it's not doing anything.

Solar panels in series add voltages, but not amps.
Solar panels in parallel add amps, but not volts.