How Long to Charge a 12v Battery With a 100 watt Solar Panel?

By Matthew Joseph Nandirio •  Updated: 06/01/22 •  7 min read

Depending on the batteries’ size, the 12v battery would take approx 5 to 6 hours to fully charge with the solar panel that can produce 1 amp of current. The charging performance could be managed with direct sunlight and other ways of adjusting the solar panel to conduct the current directly to the batteries.

Will a 100-watt solar panel charge a 12-volt battery?

Yes. It is practical to charge the 12-volt battery with the solar panel. However, the charging efficiency depends on various factors. You should ensure that the solar panel is made of high-quality material. Give a boost to solar charging with the help of direct sunlight. 

Ensure that the solar panel is always pointing to direct sunlight. 

Use the copper cable to transfer the electricity to the batteries as copper is the better solution to transfer the power. 

It is essential to know that solar energy decreases as the day starts to end. The maximum solar energy could be generated before noon. 

After that, the solar power will reduce over time as the sun starts setting to the east. 

Use solar panels that can achieve the maximum power generation capacity with the help of high-quality material used in solar panel manufacturing.

How long will a 100AH/12v battery take to charge?

It would take around 8 to 10 hours to charge the battery using the 100AH power source. It would help to consider various factors that could affect the power generation process. For example, the change in the weather could affect the sunlight. 

The cloudy day would reduce the power generation unit. Even if you get direct sunlight, maximum solar panels achieve 80 to 85 percent of their capacity while generating electricity. 

Some parts of the energy decay while transferring the electricity from the solar panel to the battery in terms of heat. 

You will never get to use 100 percent of the solar generation from your solar panel. When calculating your solar panel’s power generation unit, always keep the number 20 to 25 percent less. 

The rough estimation of the power generation would give you the number that makes the prediction easy.

How long does to charge a deep cycle battery with a 100-watt solar panel?

The deep cycle battery would require special input cables and energy supply to be charged fully in one session. However, it is not recommended to use the solar panel to charge the deep cycle batteries as they take too much time. 

Deep cycle batteries are designed for emergency use, and it requires a high power source to charge the battery in one go fully

Use a slow power charging station such as a solar-powered generator. 

The deep cycle batteries will never reach their full capacity as the energy’s decrease rate would be high compared to the power source that you have connected to it. 

Suppose we calculate the energy generation with the formula. To charge your battery at 12 volts and 20 amps will take around five hours to charge 100 amp hours battery. 

You would require a bigger solar panel if you want to charge the battery quickly. 

The given calculation is based on the perfect weather condition where you get maximum exposure to sunlight.

As the weather changes, the power generation decreases, and you will not achieve the maximum charging capacity. 

What Size Solar Panel Do I Need to Charge 12V Battery?

The portable solar panels are suitable for an emergency or camping. It can charge your RV, electronics, and Smartphone devices during the holiday in a remote area. 

The solar panel with the 12V battery pack would be the perfect package for night camping. The standard 100w solar panel with around 65×39 inches could charge by using a 12V 100-watt battery.

What precautions do you have to achieve the maximum solar power generation capacity?

There are several ways that you can use to maximize solar power generation. Charge your batteries during the day and use the energy to power your equipment at night. 

Follow these guidelines to power your battery at its maximum capacity.

1) Clean Solar Panel: 

Before the day, clean the solar panel and make them ready to capture the solar rays in the morning. 

You may have to wake up early to prepare your solar panel for power generation. The dust particles may stick to the solar panel’s surface during the night and make the panel dirty. 

It would create a layer of dust that will block the sunlight from reaching the solar panel. 

It would reduce the power generation capacity. It would be best to clean the solar panel glass every 2 to 3 hours to remove dust during the daytime. 

Use the soft cotton-made cloth to wipe the glass. Ensure that you are taking precautions while the cleaning process and the panel has been heated under direct sunlight so that the surface temperature would be very high. 

Do not touch the solar panel with a bare hand. Use the heat resting gloves to protect yourself from the burn.

2) Direct Sun Light: 

A solar panel produces energy at its high capacity when kept under direct sunlight. You may have to monitor the solar panel with manual adjustment during the day to point the panel directly to the sun. 

When the direct sunlight heats the panel, it easily gets consumed in the solar panel, and less energy is a bounce from the panel’s surface. 

As the sun moves from east to west, the sun’s direction creates a shadow on the surface. The side panel will get between the angle of the sun and the panel. 

Carefully adjust the panel to point them directly to the sun and increase the panel’s power generation capacity.

3) High-quality material: 

The major component of the solar panel is the material used in the manufacturing of the solar panel. There are several types of solar panels used in the making. 

Do some research to find the best material that consumes more solar energy and produces a better result. 

Once you identify the material, the next step is to find the reputed brand that produces the solar panel using the quality material. You should choose the product from a reputable brand. 

The cost may be a little high compared to the ordinary brand, but the solar panel’s quality would be good. The brand puts its efforts into designing the best quality products for the customer. 

Their reputation will be killed if the product is not good. 

So they ensure that the product delivered to the customer is efficient and high quality compared to the other product found in the market.

High-quality material would generate more energy compared to ordinary solar panels. Many factors are considered during the production of solar panels. 

The panel surface, glass material, power cable, etc., support the solar panel in the power generation and make the energy flow smooth.

4) Transfer of the energy:

This is primarily a neglected aspect of the solar power energy generation process. However, it is vital for solar storage and maximizing capacity. 

The cable that connects the solar panel and batteries should be high quality. Also, the material used in cable manufacturing must be good at power transmission. 

Copper is a great conductor, and it reduces the strain on the electricity while transporting the power from point A to point B. 

Also, the energy is efficiently transferred to the battery giving more energy for storage.

Final Verdict

Understanding solar power and its maintenance would improve the efficiency of the system. Follow the given guidelines and produce more energy using the portable solar panel system.

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Matthew Joseph Nandirio

Matthew Joseph Nandirio is the Founder of walkingsolar. After graduating from the University of Houston in 2002, matt started working as an electrical and electronic engineer for several multi-national solar energy companies. He has a wide range of experiences including solar system requirement analysis, planning, maintaining, debugging and even solar device development through research. He now shares his 20 years of expertise through his articles on the walkingsolar website. Further, he is also the author of two books on Solar Technology, “Solar Power for Villages” and “DIY Solar System for Dummies”.

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