12v solar panel to charge EN-EL20 battery

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Old 08-15-17, 03:41 PM
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12v solar panel to charge EN-EL20 battery

Dear all,

I am terribly sorry if this is a stupid question, but you have to start somewhere.

Iíll be going on vacation soon and Iíll be off the grid for a month.

During this time I would love to use my BlackMagic Pocket Camera to capture some video. This would mean that I would have to charge the batteries of this thing without any outlets. During my search on the internet I came across someone who had built a simple solar power solution and I wanted to check with those who are knowledgable how realistic this is.

This project can be found here: This Filmmaker Shot 14 Days Without Power in the Himalayas‚ÄĒHere's How

In short: a 12v 1amp solar panel is connected to the socket for a car cigarette lighter.

The story goes on:

Thengummoottil then custom wired the solar panel to the socket for a car cigarette lighter, using parts that any electronics or auto parts store keep in stock. Since most car battery systems are either 12V or 24V, he was able to use car chargers plugged into the cigarette outlet to keep his Canon and GoPro cameras charged throughout the project.

Is this seriously as easy as his diagram? Connect the positive and negative wire to the cigarette lighter socket and you are good to go? I must be missing something.

I would be using this for EN-EL20 batteries with a car charger that has one of those cigarette lighter plugs.

Thanks in advance!
 
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Old 08-15-17, 06:51 PM
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It looks possible but you might need to add a voltage regulator if the panel peaks to 24 volts. If the charger outputs less than 12 volts say 5 volts it already has a voltage regulator but the question would be could it handle a peak of 24 volts.
 
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Old 08-16-17, 02:10 AM
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Dear Ray2047,

Thank you!

Would a LM2596 be a suitable regulator: The Introduction of LM2596 Step Down Power Module DC-DC Converter: 4 Steps

(Do forgive my ignorance, I know nothing about this ).

Also, what would be the minimum wattage? Would I need a 12v 12w solar panel, or would 10w for example also work?

Thanks!
 
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Old 08-16-17, 05:48 AM
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I've done it with a 12v solar panel and no voltage regulator. The only issue is when it's cloudy and the output from the panel dropped below about 10.5 volts my charger would turn off. My voltage in full sun would get a bit over 14v but never anything close to 24v.

The interesting thing I noticed was about the solar panel. When the panel was uniformly shaded like from clouds it would work but produce a voltage in relation to how much sun it was receiving. If I partially shaded the panel it's output would drop dramatically. If I put my hand over the panel on a sunny day and only blocked 10% I did not get a 10% reduction in output. It dropped closer to 75%+. Must be something in the construction of the panel. I wonder if the dark cells somehow act as resistors.

As for sizing your panel you need to know the maximum draw of your charger. If you will be going off the grid to the north then you will want a larger panel as the sun will never be directly overhead. If heading down to the tropics then you could use a smaller panel.
 
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