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Solar Panels used to charge batteries. Answered

So I understand how the WestingHouse Solar Powered Outdoor Lights. They use the energy gathered by the solar panel, convert it and store it in AA batteries. The LEd is then powered by these batteries.  

This is kind of a two part question.  What exactly is stopping me from using a large Ni-Cd battery or even a car battery to be charged by an array of solar panels like the little ones that are used in the little outdoor lights??

Is there some sort of equation that would be helpful to estimate the amount of time it might take to charge these batteries?

Any help is appreciated. Thank you. 


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10 years ago

What exactly is stopping you right now is:
You don't have the panels (wired up right) and that's why you're asking.

Check the battery's specification in AH / mAH.
Energy stored in the battery is roughly the output voltage x AH x 3.6 (in Kilojoules) or output voltage x mAH x 3.6 (in Joules)

Charge time (seconds) is energy (in KJ) / panel output in watts (Amps x Volts) or energy (in J) / panel output in milliwatts (milliamps x Volts)

You will need your charge voltage to be greater than the battery voltage though, and if you're not using lead-acid a charging circuit is advisable.