Lithium Batteries are a type of rechargeable battery used in many portable electronics. 

When Lithium batteries lose their charge, they need to be ‘recharged’ using dedicated chargers. However, the sun provides us with free clean energy that can be used to power devices via Solar Panels.

Can you charge a Lithium battery with a solar panel?

Yes, you can charge a Lithium battery with a solar panel, but it is not recommended to connect a solar panel directly to a lithium battery as they can be damaged from overcharge. Also, lithium batteries require a special process of charging which will need to be followed if you are using a solar panel to charge it. 

This article will take a deeper look at Lithium batteries and what is required to charge them using a solar panel. 

Deeper look at a lithium battery and solar panels

To understand the question at hand, it will first help to take a closer look at the lithium battery and the process of charging them (I will keep it brief). 

Rather than going through unwanted information about the battery, I will cover its key characteristics 

Lithium Ion batteries  

While there are many different types of Lithium batteries, the most common of them is the Lithium Ion. So this article shall concentrate on this particular type to see if it is possible to charge it with a solar panel. 

Most (if not all) batteries are given their name because of the type of chemical composition they are made of. In this case, the battery uses lithium ions.

During the discharge cycle, the lithium ions move from the negative terminal (cathode), through an electrolyte to the positive terminal (anode).

Different types of Lithium Ion Batteries

Lithium Ion batteries come in a variety of shapes for different applications. 

• Small cylindrical (single cell with, solid body, with no terminals)
• Large cylindrical (single cell,solid body, with threaded terminals)
• Flat or pouch (soft, flat body)
• Rigid plastic case (large threaded terminals) 

Other key characteristics of Lithium Ion batteries are their Nominal voltage and Current Capacity.

Nominal Voltage: This is the normal voltage that the battery operates at. Some batteries might have a higher voltage at full charge, however, this value will soon drop down to its nominal voltage after a predetermined amount of time. 

All the packages above come with a nominal voltage of 3.7 volts. However, cells can be connected in series to generate larger voltages.

For example, three lithium-ion cells can be connected in series to give a voltage of 11.1 volts, or four cells can be connected to give a voltage of 14.8 and so on. 

Current capacity: Is the amount of current that the battery is capable of storing. It is usually given in Amp-hours (Ah) or Milliamp-Hours (mAh). 

Lithium-Ion batteries come in a range of current capacities ranging from as low as 40 mAh all the way to 2.6 Ah. 

To increase the current capacity further, batteries are connected in parallel. However, this is a bit more of a complicated process as the internal impedance of each battery needs to be matched. 

What is the process involved to charge a Lithium Battery

The Lithium-Ion is a special kind of battery compared to other batteries of different chemistries. This type of battery has strict requirements when it comes to charging it. 

The battery charger is a voltage limiting device with some differences to other chargers. 

The key differences include;

• Higher voltage per cell
• Tighter voltage tolerances
• Absence of trickle or float charging

Trickle charging is when a battery charger is able to charge a fully charged battery at a rate equal to its self-discharge rate, which allows the battery to maintain its full charge level. 

A lithium-ion battery charger does not offer trickle charging because the battery cannot accept overcharge. The battery can become unstable if charged above its nominal voltage which could result in permanent damage. 

Damage can result in the form of an explosion! 

The charger comes with strict settings that adhere to the restrictions that come with charging this type of battery which will include features such as an end-of-charge detection circuit  to monitor when the battery is fully charged. 

What is a solar panel?

Now, let’s take a closer look at the solar panel. 

Solar panels are increasing in popularity, and becoming the go to for providing a means of free, clean renewable energy to homes, business, and much more. 

They work in conjunction with the awesome powers provided by the sun, which is the biggest source of solar energy in our galaxy, the milky way. 

Solar panels are panels that convert light (solar energy) from the sun into electricity which can be used to power electrical and electronic equipment. 

They come in a variety of sizes and power outputs depending on the needs of the application it will be used for. 

Connecting a solar panel directly to a load

So, these awesome panels have the ability to provide power to electrical and electronic devices. But, is it possible to connect them directly to a load?

Connecting a solar panel directly to a load is not the most ideal option as there are a few drawbacks;

• The load will be unable to draw the maximum power at any given instant from the solar panel
• The solar panel could be overloaded due to the demands of the load
• It might be a cloudy day, and the sun might pop in and out which means you won’t have a steady stream of power (so they are weather dependant)

A better option would be to store the energy produced by the solar panel in a rechargeable battery where the load can then draw power from.

How do you charge a battery with a solar panel?

Solar panels are rarely used by themselves to charge a battery. They will be one of a few components used in what is known as a Solar Power System. 

The solar power system can then be used to power electrical and electronic loads. 

Components of a solar power system include;

• Solar Panel(s)
• Charge Controller 
• Rechargeable battery
• Inverter (AC applications) 

Let’s take a look at each component and what job it has in the overall system. 

Solar Panel – has the task of converting sunlight into electricity.

Charge Controller – the current produced by the solar panel is fed into the charge controller. The controller regulates the current produced by the solar panel to protect the batteries from overcharging. 

The controller can detect when the battery is fully charged and can stop, or limit the current (trickle charge) received by the battery. 

They also have the job of protecting the solar panel from reverse current (current being fed back into the solar panel from the batteries) when there is no sunlight. This can also lead to the battery losing unwanted charge. 

Rechargeable battery – rechargeable batteries are where the power generated by the solar panels is stored. They come in a variety of shapes, sizes, chemical compositions, voltages, and current capacities. 

Inverter – The current produced by a solar panel is normally a Direct Current (DC). However, solar panels are used in many settings where Alternating Current (AC) is required. An inverter has the capability of converting this DC current to an AC current. 

Can you charge a Lithium battery with a solar panel?

Yes, you can charge a lithium battery with a solar panel (this is assuming that the solar panel has the right output power requirements to charge the battery). 

However, there are some issues to consider before doing so. 

The first major one being overcharging. We learnt earlier that lithium batteries (especially the Lithium Ion variety) are easily damaged when they are charged above their nominal voltage. 

For this reason, lithium battery chargers do not have trickle charging. The charger is designed specifically to stop charging the battery when it has reached its ideal voltage. 

Connecting a solar panel directly to a lithium battery is not an ideal scenario, as the solar panel has no means of knowing when to stop providing power to the battery.

It will constantly be feeding energy to the battery (as long as there is sunlight) which will lead to overcharging and damage to the battery. 

Other issues include what we discussed earlier in the section about connecting a solar panel directly to a load which include;

• The lithium battery not being able to draw maximum power from the solar panel
• Solar panel being overloaded
• Charging the lithium battery is dependant on the weather (cloudy days are not ideal)

What is needed to charge a Lithium Battery with a solar panel?

While there are some issues when it comes to charging a lithium battery with a solar panel, all is not lost! There is a way to work around these issues.

So what is needed to charge a lithium battery with a solar panel? 

You will need the same components we saw earlier in the section ‘how to charge a battery with a solar panel’. In this instance we have a solar panel, and a rechargeable battery. So all that is required is a charge controller.

The charge controller will take care of the main issue of the lithium battery being overcharged. It will also provide a constant current to charge the battery, and protect the solar panel from any reverse current. 

However, a note has to be made. Since there are many different types of batteries, there will also be many different types of solar charge controllers to meet the individual needs of each type of battery.

So, you will need to buy a solar charge controller designed for lithium batteries so that it will stop charging the battery when the nominal voltage is reached. 

The post Can you charge a lithium battery with a solar panel?
appeared first on Electronic Guidebook.

One of the main sources is the Sun. 

Solar panels capture energy from the sun and convert it to electricity which we can store and use later to power devices.

Solar lights utilise solar panels and the sun’s energy to light up spaces during the night time. They are commonly found in front and backyards of homes helping illuminate paths, as well as providing great ambience.

But, some of the time solar lights come with batteries that have a low capacity (denoted by the symbol mAh), which don’t last very long.

So, can you use a higher mAh battery in solar lights? Yes, you can use a higher mAh battery in solar lights to extend the hours that it stays on during the night. You will just have to make sure the dimension (size), as well as the voltage of the battery you are using matches the original solar light battery dimension and voltage which you are replacing. 

Deeper look at the rechargeable battery and its mAh rating

Solar lights are a great addition to any front or backyard. They can add a path of illumination when you return home during the night, or add some flare to your garden.

The main components of a solar light include;

• Solar panel
• LED (Light Emitting Diode)
• Charge controller
• Rechargeable Battery

The main component we are concerned with when asked the question of whether you can use a higher mAh battery is of course, the rechargeable battery.

So, let’s take a closer look at the rechargeable battery.

The mAh rating of a rechargeable battery used in solar lights

Rechargeable batteries have the ability to be recharged and used again to power electronic devices.They differ from standard one use batteries (disposable batteries) which need to be disposed of when they run out of charge.

There are many different varieties of rechargeable batteries available. Below are few of the characteristics which vary from one rechargeable battery to the next;

• Chemical Composition (Li-Ion, NiMH, NiCD, Li-Ion polymer)
• Size
• Shape
• Recharge rate
• Discharge Rate
• Capacity (milli-Ampere-hours → mAh)

The capacity (mAh) of the battery is the main characteristic of the rechargeable battery that we will focus on. 

The mAh rating is how much charge a battery is capable of storing. 

The rating of how much a battery can store is given by milli-Ampere-hours (mAh) or Ampere-hours (Ah). For the rest of the article I shall refer to the capacity as mAh.

The mAh rating is used for batteries with lower capacities, while larger batteries used the Ah rating. 

A note to make is how long a battery will last also depends largely on the current draw of whatever the battery is powering. Powering a motor is going to require more current than a LED for example. 

Looking at a practical example will give you a better understanding of how battery capacities work.

Below we have two batteries (battery A and battery B), both with different capacities. There is also an LED that will be the component that the batteries will be powering (which draws a current of 20mA).

Scenario 1: The LED is being powered by Battery A (500mAh). Since we know how much current the LED draws, we can calculate how long the battery lasts for. 

Below is the equation to calculate how long a battery will last depending on how much current is being drawn. The time is given in hours.

If we take Battery A’s capacity (500mAh) and divide it by the current draw of the LED (20mA), we get 25 hours. So, we know using a 500mAh battery can power a LED that draws 20mA for 25 hours (in an ideal world). 

An important note to make is the units you are using when doing these calculations. 

If you are using mAh ratings, then the current draw of the device you use in the calculation will have to be in mA. If the Ah rating is used, then the current draw used in the equation will have to be in A. Or, you could convert the Ah rating to mAh by dividing it by a 1000.

Scenario 2: The LED is being powered by Battery B (1000mAh).

Now, we are powering the LED with a 1000mAh capacity battery (an increase of 500mAh). So, taking Battery B’s capacity (1000mAh), and dividing it by the current draw of the LED (20mA), we get 50 hours.

As you can see, by increasing the mAh rating or capacity of the battery, we can increase the time the LED stays on for.

Can you use a higher mAh battery in solar lights?

Now that we know a little bit more about batteries and their mAh rating let’s look at whether we can replace a smaller mAh battery with a higher mAh one. 

Replacing the rechargeable battery that comes standard with a solar light depends on a couple factors.

Factors you need to consider before using a higher mAh battery for solar lights

Replacing a smaller capacity rechargeable battery with a higher capacity one can be done, but there are a couple of factors that need to be considered before doing so. 

Factor #1 when using a higher mAh battery for a solar light: Voltage 00

The first factor you will need to consider when replacing the standard battery of the solar light with a higher mAh one is the voltage of the battery.

The solar light will have a maximum voltage rating that it can handle (which is largely determined by the voltage rating of the Light Emitting Diodes).

You will have to make sure the battery you choose does not exceed these maximum ratings as you could run the change of damaging components.

Also, if you choose a low voltage battery, you will not be able to provide enough power to run the Light Emitting Diodes.

Factor #2 when using a higher mAh battery for a solar light: Size  

The next factor to consider is the size and shape of the battery (physical dimensions).

Rechargeable batteries come in a variety of shapes and sizes. Below are the most common sizes of rechargeable batteries:

• AAA
• AA
• 14500
• 16340
• 18650
• 26650
• Coin Cell
• D cell
• C cell

Solar lights also vary in shape and size and therefore use different types of rechargeable batteries. You will have to make sure the battery you are replacing the standard one with, matches it in size.

Can a smaller sized battery have higher mAh ratings? 

You might be wondering if it is possible for the same size battery to come in a higher mAh rating even though its physical dimensions haven’t changed. 

The answer is Yes. 

As there are different chemical compositions of batteries available, you will be able to find a battery of higher mAh rating while still matching the size of the battery you are replacing in the solar light.

Advantage of using a higher mAh battery for solar lights 

Why would you want to replace the standard battery in solar lights with a higher mAh battery?

Using a higher capacity battery comes with some notable advantages.

As you saw earlier with the LED example and the two batteries of different mAh ratings, as you increase the capacity of a battery, you increase the amount of hours that the LED can stay on for. 

I chose that example specifically for this article as it applies to solar lights. 

Solar lights come with stock rechargeable batteries with very low capacity, that almost run out in an hour or two.

Increasing the battery mAh rating will mean that the solar light will stay on longer during the night. 

The next advantage of using a higher mAh rating battery is on days when there is not sunshine. You might have one day of sunshine and the next is cloudy.

If the battery mAh rating is considerably large, and the LED of the solar light does not consume a lot of current, you have the advantage of running the solar light two nights in a row with only one day of sunshine (but this does also depend on how much current the solar panel can provide as well as the exposure to sunlight).

Disadvantages of using a higher mAh battery for solar lights

One of the biggest drawbacks of using a battery with higher capacity is that it is going to take longer to charge the battery to full capacity.

I mentioned above that you could possibly run the solar light for two nights after only charging it for only one day under the sun.

However, it takes more for that to happen. The solar panel will need to be able to provide enough current to charge the battery to full capacity for the limited time the sun is out for. 

Also, the sun changes its position during the day, so the solar light will need to be placed in a location where it is exposed to the right amount of sunlight.  

Main purpose for using higher mAh battery in your solar lights 

Changing the current battery of your solar light depends on your needs. If you need to increase the time that the solar light stays on during the night, it makes sense to use a higher mAh battery as standar solar light batteries tend to be lower in capacity.

Just be aware that if your solar panel does not provide adequate current, that it is going to take a longer time and a lot more sunlight to recharge your battery to full capacity. 

What are the most effective mAh rating batteries for solar lights?

A battery with too high a mAh rating might take too long to charge, while a battery with a lower mAh rating might run out too quickly.

So, is there an ideal mAh rating that will be the most effective for your solar lights? 

This all depends on factors that we have mentioned earlier like sunlight exposure, and output current of solar panels.

If you have a solar light and are just changing the battery, you will need to check what the average current your solar panel outputs during a standard sunny day. 

Placement of the solar light should be of great importance. 

Accordingly, you can choose a rechargeable battery that is in the ‘sweet spot’ of being fully charged, and lasting a long time depending on the current your solar light panels provide.

Can you use non-rechargeable batteries in your solar lights?

Solar lights are meant to be self-sufficient. This means they can run by themselves without you having to do anything to operate them.

You can use non-rechargeable batteries (disposable batteries), however, you will have to dispose of them after they have run out of charge, because, well you cannot recharge them. 

Solar lights are named as they are due to the fact that they use solar energy to charge rechargeable batteries. Using disposable batteries would be paradoxical. 

How to change battery in your solar light 

Below is a great video highlighting how to replace solar light batteries. While your solar light might not be the same, the principle is the same for all solar lights.

The post Can I use a higher mAh battery in solar lights? appeared first on Electronic Guidebook.

You might know how frustrating it is when your mobile device is about to run out of battery and you have no way of charging it. 

A power bank solves this issue as you can recharge your mobile device on the go when you do not have access to a power outlet. 

But, what if your power bank is out of battery too? Can you charge a power bank with a solar panel? You can charge most standard power banks using solar panels. The ability to charge a power bank with a solar panel depends on how much power the solar panel can output which is determined by its power rating. There are different types of solar panels that come in different shapes, and sizes as well as power ratings. So, you will need to select a solar panel that is capable of supplying the voltage and current required to charge a standard power bank. 

Other factors that can affect charging the power bank with a solar panel are the amount of sunlight, angle of sunlight, surface area etc.

A deeper look at a solar panel and power bank

Taking an in-depth look at solar panels, and power banks will give you a better understanding on what type of solar panels can charge a power bank.

A note to be made is that, you get power banks that come embedded with a solar panel on them. These power banks have been tested with that particular solar panel to ensure that it can be charged efficiently. 

Our concern is whether you can use a standalone solar panel to charge a standalone power bank.

The Solar Panel

A solar panel has the ability to convert sunlight into electricity. It does this using a process known as the photovoltaic effect.

It is a great choice for powering homes, businesses, etc, as it is a form of clean renewable energy.

Solar panels come in a variety of ratings, shapes, and sizes.

The ratings of the solar panel are of great importance when creating a solar power system (which is a combination of a solar panel, charging module, and battery).

Solar panels have three ratings that need to be known which include ; Power, Voltage, and Current. 

These ratings are the maximum ratings that the solar panel is capable of generating. However, the solar panels ability to deliver these maximum ratings depends on the intensity of sunlight. 

Due to this, it is not effective to power electronics directly using a solar panel, as the power levels are not constant and vary with varying intensities of light. 

Instead, a solar panel is used to charge a rechargeable battery source which can then be used to power electronic devices. A charging module is used between the solar panel and battery to regulate the incoming power from the solar panel to make sure a constant voltage and current is delivered to the battery.

The Power Bank

Our mobile devices all have a limited amount of power which eventually runs out. This can be an issue if you are travelling and have no way charging your device.

A power bank was created as a solution to that problem. It essentially is a portable charger that can charge your mobile devices when there is no other means of charging them.

Like the solar panel, a power bank comes in a variety of shapes, sizes, current capacities, and ratings. 

The main specifications to look for when purchasing a power bank is its Output Voltage, Input Voltage, Output Current, and Capacity.

Output Voltage – This is the maximum voltage a power bank can output (you will need to match output voltage of your power bank to the input voltage of your mobile device)

Input Voltage – This is the input voltage required to charge the power bank.

Output Current – The maximum amount of current the power bank is capable of delivering 

Capacity – This is the maximum amount of charge the power bank can store when fully charged. The more charge that the power bank is capable of storing, the more times you will be able to charge your mobile devices. 

The conventional way of charging a power bank is to use a wall charger (which you use to charge your mobile device) via its input port.

Selecting a solar panel to charge a power bank

There might be times where you might have forgotten to charge your power bank before heading out on your long journey (or you might be on a journey where there isn’t any electricity available).

So, now your mobile device and power bank have no charge!

To avoid this situation from recurring again in the future, you have the option of using a solar panel in conjunction with the power bank to effectively create your own mobile solar power system.

As you saw above, a solar panel by itself cannot power electronics as its output power varies and requires a battery to store all that energy. 

A power bank can be used as that battery source and store the charge generated by the solar panel. The good thing is that the power bank has an internal charging module that can regulate power levels delivered to its battery via the solar panel.

Most mobile electronic devices (like smartphones), operate at 5 volts. Therefore, you will need a power bank that has an output voltage of 5 volts.

Due to this, a solar panel with a voltage rating of 5 volts will need to be chosen as well. 

A solar panel that is say 3.7 volts, will not have capability of charging a 5 volt power bank. So, the output voltage rating of a solar panel needs to match the input voltage rating of a power bank. 

What solar power rating is required to charge a power bank?

How effective a solar panel is when it comes to charging a power bank comes down to its power rating.

The maximum power rating (P) of a device is the product of its maximum voltage and maximum current (P = V x I). Its unit is watts.

An example would give you a better understanding. Below is a table of values of current and voltage for a solar panel and power bank (values are chosen randomly for this example).

The solar panel can charge the power bank, as it matches it in voltage values. However, it does not do it very effectively as it only delivers 2.5 watts of power, and the power rating of the power bank is 10 watts.

So, to be more effective, a solar panel with a higher output power rating will need to be selected for the power bank in this example.

Since the voltage of the solar panel needs to be 5 volts, its current will need to increase from 0.5 A to 2A in order to match the power banks power rating. 

Why not just charge a mobile device directly with a solar panel?

A mobile device needs a constant voltage and current to be charged effectively. Wall chargers can provide them with this constant power that will charge them at constant rate.

While it is not impossible to charge a mobile device directly with a solar panel, it isn’t very practical. This is because the solar panel will not be able to provide constant power all the time. 

So, a better option is to store the energy generated by the solar panel in a battery source which can then get delivered to a mobile device at a constant rate.

What else is needed to charge a power bank with a solar panel?

To connect the solar panel to the power bank, you will need the right type of cable which fits the input port of a power bank. 

There are many different types of input ports, but the most common of them being Micro-USB. This however, is slowly being replaced by Type-C ports. 

So, you will need to check what kind of port your power bank has, and accordingly wire the solar panel with a cable that matches that port. 

Do you need a charging module? No, you will not need a charging module as the power bank already has its own charging module. 

How long will it take to charge a power bank with a solar panel?

A power bank’s capacity is the maximum amount of charge it can store. The larger the capacity of a power bank the more charge it will be able to store, and vice versa. 

The unit for a power bank’s capacity is given in mAh (milli-amp-hours). 

To calculate how long it will take to charge a power bank to its maximum capacity, you will need to know its maH value, and the amount of current being supplied by the charger. 

So the time it will take = mAh / current.

For example if we have a power bank with a capacity of 1000 mAh, and a current of 1A is provided by the charger, it is going to take 1 hour (we need to use Amps values, so 1000mAh = 1Ah. We then divide 1Ah/1A to get 1 hour)

But, since we are using a solar panel to charge the power bank, another factor that will determine how long it will take to charge it, is how constant the level of current is being delivered by the solar panel.

The amount of current being delivered depends on the output current rating of the solar panel and the amount of sunlight that the solar panel is exposed to. The more sunlight, the greater the power output. 

So, the solar panel will need to be exposed to constant intensity of sunlight in order for the power bank to be charged at a known rate. 

Other factors that will affect how long a power bank will take to charge using a solar panel

So, how long a power bank will take to charge using a solar panel depends on two variables; the capacity of the battery, as well as the amount of sunlight the solar panel is exposed to.

But, there are other factors that come in to play as well:

• Placement of the solar panel – as well all know the sun does not stay stationary during the day. So, the placement of a solar panel to catch the most sunlight should be taken into consideration
• Whether the solar panel is stationary or not – You might be doing a hike and need to charge the power bank daily. You could place the solar panel on your backpack as you walk. However, this might not effectively capture the most amount of solar energy as you could be changing direction constantly. 
• Weather – Obviously the weather is a major factor. You won’t get the most out of the solar panel if the sun is not present on cloudy days. 

Where can you charge a power bank with a solar panel?

Charging a power bank with a solar panel requires one thing, sunlight. 

Below are some great places:

• In your car
• Outside your home
• Inside you home 
• Backpack as you walk
• Pretty much wherever you can find sunlight =D 

Advantages of charging a power bank with a solar panel?

One of the greatest advantages of charging a power bank using a solar panel is that it is great for our planet. Since we are generating electricity using the sun, it does not harm the environment in any way and is one of the most used ways of generating renewable energy. 

Another great selling point is that it is free! You will be saving on your electricity bills when you start charging your power bank with a solar panel. 

Also, since the sun shines on pretty much all parts of the earth (that I know of), you can charge your power bank, and therefore your mobile devices with a solar panel, no matter where you are!

Disadvantages of charging a power bank with a solar panel?

All things that come with advantages, will have its disadvantages, unfortunately

Here are some of the disadvantages of using a solar panel to charge your power bank:

• Only effective when sun at its brightest
• Cannot charge at night
• Weather dependent
• Charging times vary depending on factors like angle of sunlight, intensity of sunlight and weather.

How can you charge a power bank faster using a solar panel?

If you notice that it is taken a long time to charge your power bank with a solar panel, even when the sun is at its brightest, you have three options:

• Add another solar panel with the same rating in parallel. This will double the current output. Adding a third solar panel in parallel will triple the current output, and so on.
• Upgrade your solar panel to one which can deliver more current. 
• Get a bigger solar panel (one with greater surface area)

The post Can you charge a power bank with a solar panel? appeared first on Electronic Guidebook.