How to Use 12 Volt Portable Solar Powered Battery Chargers

Solar power is continuously gaining momentum and popularity. There are now solar chargers designed to power cell-phones, cars, laptops, etc. The solar charger harnesses energy form the sun and stores the energy within its battery for later use. Typically, a solar charger can hold on to its charge for up to a year. The advantage to using a solar charger is that it eliminates all of those unnecessary, bulky chargers for every electronic device.

The Most Recommended Solar Chargers Are:

It may be difficult to choose between the best solar chargers because there are a lot of great models out there that basically perform the same functions. Upon being fully charged, the solar charger can fill a cell-phone’s life twice or play up to twenty hours of music.

Solar battery chargers 101

Keep in mind that Your panel will produce 100% full wattage output when placed on direct sunshine. Before buying a portable solar power system, it’s good to answer these questions:

  • How long would the solar panel take to charge a 12 volt battery?
  • What’s the ideal wattage for a solar charger?
  • How can I control if it works fine?
  • Will it fry my battery?

Most models have an illuminated LEDs that lets you know the panel is charging. Other have a built in controller to block the charge when the battery is full.

Choose the right solar recharger

To explain in further detail about the conversion, basically an hour of sunshine will equal about an hour of music, or 25 minutes of conversation. The batteries in most solar units last up to about a year, and the charger works with numerous gadgets: Bluetooth, iphone, games, digital cameras, etc.

The charger is extremely light and easy to transport making it optimal for travel purposes.

The General rule to calculate the average charge time:
Take Amp/hour rating of the battery and Divide by the charger rating (in amperes) and then add about 10% for the extra time to top off the battery
I.e. Assuming You have a typical full size auto battery, it is about 50 amp hours.

To Calculate how much time You’ll need to charge the battery with a 15 Watt solar charger You’ll need:

  1. Calculate the Ampere per hour of the charger: 15 Watts /12 Volts = 1,25 Amperes
  2. Calculate the division: 50 amp hours / 1,25 ampers = 40 Hours of direct sunlight
  3. Add 10%: 4 hours

A 15 watt charger is great for vehicles such as cars, boats, ATV’s, even electric fences. 7  watts are perfect for laptops and camcorders. A 2  watt charger is perfect for cell phones, ipods, and smaller cameras.

There is a formula to help describe the way solar energy works: the output for solar energy is described as watts. The wattage can be understood by multiplying the voltage by the amperage.

More specifically: volts x amps x watts = / e.g. a six volt 30 watt solar panel measuring ten by 22 inches has a voltage of about 8.55, and amperage of 1.75.

One can determine the correct amount of wattage needed based on how much each electronic device expels.

How Many Hours Does the Solar Charge Give You ?

The answer depends on the number and size of the solar panels and the set-up or system installed in your area. The prevailing weather condition in your location is another factor. Winter days, rainy and overcast skies can affect the capacity of solar panel systems to absorb and produce solar energy. Even the time and position of the sun are important factors.

If conditions are perfect, the energy radiating from the sun in the mid-afternoon is usually at its peak compared to the early morning and late afternoon sunlight. If you live in an area with sunlight all year round, your solar panel system will produce optimum results. Avoidable factors such as obstructive shadows from nearby objects and improper mounting of solar panels can also affect energy output.

Calculating the number of hours a solar charge provides depend on the previously mentioned factors. For example, a 60 watt solar panel in a location which receives at least 6 hours of optimum sunlight can generate an average of 360 watt hours per day. On the other hand, the same 60 watt solar panel in an area which receives 2.5 hours of sunlight can only generate 150 watt hours per day.

How Big Of A Solar Panel Is Needed To Charge A Deep Cycle Battery?

Before looking at the optimal size of a solar panel that is needed to charge a deep cycle battery, you first have to look at the design and makeup of a deep cycle battery. Deep cycle batteries are your regular batteries such as the ones that are in cars, RV’s, and boats. They are designed to be charged and recharged thousands of times. These batteries are rated according to amp hours. This means how many amps it can provide over a set amount of hours. The most common is a 350ah battery. This means it can provide 35 amps of power over the course of ten hours of usage.

When it comes to the best solar panel needed to charge a deep cycle battery, a 12 volt panel is the most common that is used. The best way to figure out what sized panel that you will need you will calculate the powering load of the panel (3 amps is the norm with a 12 volt panel) multiplied with the amount of time that the panel gets the most sun, which during a very sunny day can run between 4 and 6 hours. With that being said, a 12 volt panel at the most can provide 12 to 18 amps to your deep cycle battery. Figure this out and that means one good day of sun can lead to 5 hours of use to a 350ah battery.

What Can A 5 Watt Solar Panel Be Used For ?

A 5 watt solar panel is good for operating a multitude of different products. Automatic animal feeders and electric gates are two examples of products that make use of 5 watt solar panels. In some instances, this particular wattage solar panel is used for charging three, six, and twelve-volt batteries. Unlike common battery chargers which are plugged into an electrical outlet, solar panels are meant to be used during power outages or other scenarios where electricity is not available.

Present-day technology offers a world of conveniences. Many of these products are operated by batteries, electric current, or both. However, there are many different types of batteries to choose from. The product itself will have markings or enclosed directions stating what type of battery to use. People who take camping trips or have simply decided to use an alternate form of energy benefit greatly from 5 watt solar panels.

Autmobile, boat, and rv accessories use twelve-volt batteries all the time. Driver’s frequently opt to attach the solar panel to the dashboard or visor when the vehicle is turned-off and sitting in the sun or while operating the vehicle in the sun. A 5 watt solar panel is good for many uses.

How Long to Charge Battery with 13 Watt Solar ?

Some things to remember with a battery is it takes time to re-charge. With a thirteen watt solar battery you can expect to have it all charged within a week. The reason I say you should wait a week is because there are many different factors included on the battery being able to charge in a reasonable amount of time.

Some factors that come in to play about the battery is it’s condition, the usage of the battery itself (how long you use it, do you use it everyday? Once a week?) and finally the purpose of the battery. If you are using the battery for high machinery that can cause you to literally use the battery up within a few hours.

These are just a few main factors that can make charging this big of a battery a problem. Its important to remember that these types of solar batteries do not charge from straight 0 you will need to charge it all week.

An important tip when charging a battery like this you need to start off when the life of the battery is at least at 50 percent – this way you do not waste time trying to charge it from 0 percent and can at least get t fully charged within half a week.

What Can You Use With A 45 Watt Solar Panel ?

You’ve just purchased a 45 watt solar panel. Now what? Can you power anything with solar panels or do they have their limitations? Unfortunately, there is no simple answer to these questions.

A wide array of factors come into play when using solar power, like what type of battery should you use to store the power the solar panel produces? The short answer is, use a battery with the highest amperage rating available. You’ll also need a power inverter to change the power produced by the solar panel into usable energy. Which inverter should you buy? Buy one with the highest wattage rating you can afford.

Here’s a sample list of devices that will run on 45 watts or less and the power they consume:
Fish Tank-4w
Ceiling Fan-24w
CFL Light Bulb-18w
Laptop Computer-45w
17 Inch LCD Monitor-40w
Nintendo Wii-18w
Cordless Phone-3w

Power produced by a 45 watt solar panel will vary from day-to-day. Does the sun have to shine all day long for solar panels to work? Yes and no. Of course, more sun will produce more power. How long will a device run? That depends on how much the solar panel has charged the battery. A 45 watt solar panel is certainly not suitable as a whole-house power source. However, 45 watts of power can be of benefit for some applications.

Solar Battery Controllers

In most case a solar charger controller is highly recommended. The Solar Controller will continuously monitor the charge and cut it off when charging is complete.

It helps in:

  • Preventing overcharge
  • Improve charge quality
  • Prevent battery discharge in low or no light conditions.

Some solar panels are made with blocking diodes pre-installed they prevent battery discharge during low or no light conditions.

Once connected, you can charge your 12-volt battery nonstop for days without damaging the battery.


solar battery inverter
Inverters turn DC (Direct current) power into AC (alternate current) power, the type of current that powers everyday appliances.

Final Suggestions

There is no need to buy multiple solar chargers for each electronic device owned, so invest in one with the best quality. If the solar charger is needed to power a lot of devices frequently, makes sure to buy an additional panel at about fifty dollars to ensure the maximum access to available sunlight; this panel allows for powering two laptops at once, and it should feel good to know that the electronic devices are functioning on renewable energy.

For cars it makes sense to purchase a solar charger that sits on the dashboard and soaks up the sun. These are not designed to jump start the car battery, but rather to keep the existing car battery at full charge and functioning.

Basically, if used properly it can extend the battery’s life, which of course saves money in the long run. Therefore, when individuals use many gadgets by plugging them up to the cigarette lighter, the solar charger helps against stress and fatigue that is placed on the battery.

Of course it is still possible to find one solar charger that supplies power to all electronic devices, including a car battery. As mentioned previously, there are many really good choices out there, so investigate properly, ask professionals which best fits their needs and enjoy the fact that you are participating in the usage of renewable energy, an environmentally wise choice.

116 thoughts on “How to Use 12 Volt Portable Solar Powered Battery Chargers

  1. Wendy B

    I have recently got a 45 watt solar panel with a controller unit. I am hooking that up to a new deep cycle battery that is rated at 200 mins at 23 amps. My question is: Can I hook up an inverter at the same time the panels are charging – to the same terminals??? Or should we get a second battery to use while the first is charging??? I don’t want to damage the equipment (or myself!!)

    I have a 400 watt inverter. This is our first foray into solar and we are starting small and trying to learn all we can. I know we will have to expand the system if we want to run more that 2-3 lights (mostly CF bulbs), but figured we would start out with a smaller portable panel.

    Thanks for any info you can provide us!!!

  2. San Myat Htun

    Please any one can advice me which size of solar panel (in watts) is Ideal to charge 6v ,4.5 Ah battery.Plan to use in poor countries for lighting purpose .Assume to be use most of power stored at night.(almost finished).Area supposed to used is in Tropic and subtropic region.

  3. Richard

    What wattage solar panel do I need to charge a 12 volt battery pack that is connected to a wind turbine?

  4. smartBunch

    Can someone please help me learn to do math? I need help figgerin out how ta davide.

  5. Tony Moss

    Hi, I was needing help in some figures on solar. I have 2 115 volt AC pool pumps, and I run them 4 hours a day, I have 5 or 6 15-watt solar panels already, and I have an 5000 -watt inverter also, would that be enough to keep a set of deep cycle batteries charged or do I need more panels? doing the ohms law it looks like in 4 hours time these pump motors will use around 15,000 watts, and I do believe that the panels has like a 1.2 amp output, dont know how many batteries I need yet , or if I even have enough panels could some one help a little bit and thanks in advance

  6. warren

    i have a 120 watt panel its got a 12v reg on it does charge wont even light a test light shows nothing through a multi meter its new i dont know anything about these things ie solar give some help many thanks regards wazza

  7. len

    A 50Watt laptop unfortunately will NOT run off a 7 Watt solar panel. A 50Watt laptop will run off a 50Watt solar panel.

  8. dan

    I repair damaged solar panels and been buying n using them. Kenya. I can teach you how!!

  9. jacques st louis

    i would like to know how many watts of solar panel i need to charge 8 12vlts batteries to use on an inverter for household use.

  10. david ngetich

    would like to know capacity of batery in terms of Ah that suits 51Watt solar panel.Is there a formula to calculate this

  11. Andrew

    So how long will it take to charge a 12v 18amp sealed battery with a charge controller using a 10w solar panel.

  12. Glen Samson

    Have small trailer, 11′. What wattage is necessary to get a battery fully charged during daylight? Colorado gets lots of sun, so assuming very good exposure and a full day of charging?

  13. Unlimited

    hi I have little knowledge about solar panels and I just ordered 5 pieces of 250 watts solar panels which it 1250 watts when combined or used together, I really want to know what kind if BATTERY(simple or deep cycle) and what kind of INVERTER will I need. Lastly , can I use the energy 24 hours a day since I live in a tropical zone and sunshine is about 7 hrs a day. thx

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