They are a series of small Light Emitting Diodes (LED’s) that run along a string similar to Christmas Lights.

However, christmas lights use bigger, much larger LEDs compared to fairy lights. 

Due to the size of the LEDs used in fairy lights, they aren’t used to illuminate spaces but rather used as decoration. 

Fairy lights are designed to be powered with batteries as they are used in applications away from power sources as well as to make them a bit more aesthetically pleasing. 

But, how long do batteries last in fairy lights? The standard batteries that come with fairy lights last around 5- 25 hours depending on the length of the fairy lights. Below is a table summarizing the different lengths and how long the batteries will last. Note, this is an estimate based on calculations in an ideal situation.

However, how long  batteries last in fairy lights comes down to many factors which include;

• Battery capacity
• Current consumption of  the LEDs used in the fairy light
• Length of fairy lights (more lights = greater current consumption) 
• Quality of batteries 
• How long the fairy lights are used for 

In the following article I will list in more detail these factors and give you guidelines on how to roughly calculate how long the batteries and fairy lights you are using will last. 

As, not all the factors will be the same for everyone, values will vary.

Factors that affect how long batteries last in fairy lights

The value of 5 – 25 hours that I mentioned earlier is just an estimate of how long standard Coin cell batteries, plus a standard set of fairy lights will last for. 

But, there are many other factors that play a part in determining whether the batteries will last for a longer or shorter amount of time. 

Let’s take a look at them.

Factor #1 of how long batteries last in fairy lights: Battery capacity

The first major factor which has a large influence on how long batteries in fairy lights last for is the Battery’s Capacity. 

Battery capacity is defined as the amount of charge a battery can hold.

A great analogy for this is a car’s fuel tank.

Some cars have bigger fuel tanks than others, giving them the ability to hold more fuel and thus allow them to travel farther. 

This is the same for a battery. 

However, while physical dimension does play a role in determining it’s capacity, Chemical composition plays a big role too. 

An important value that indicates a battery’s capacity is it’s Amp-Hour (Ah) or milliamp-Hour (mAh) rating.

These ratings tell us how many amperes( or milliamperes) a battery can supply for one hour. Bigger batteries will tend to have their ratings in Ah, while smaller batteries will have it in mAh. 

For example, let’s say we have a AA sized battery which has a battery capacity of 500mAh.

This tells us that the battery can deliver up to 500mA for an hour or, 100mA for 5 hours, or 50mA for 10 hours.

To calculate how long a battery will last (in hours), we divide its capacity by the current draw of the circuit.

This rating will ultimately determine how long those batteries in your fairy lights will last for which can be found on most batteries. 

If the battery does not display these values, you can search the brand of battery online and check its datasheet which should indicate its battery capacity.

The higher the Ah/mAh rating the battery has, the more charge it can hold. 

Factor #2  of how long batteries last in fairy lights: Current consumption of Lights

The battery’s capacity is only one part of the equation when it comes to how long it will last when powering electronic devices such as fairy lights.

The second factor is Current Consumption of the lights used in fairy lights. 

An example would be the best way to illustrate this. 

Let’s use the same battery capacity in the previous example of 500mAh.

This time the battery will be powering two different light sources, both of which have different current consumptions.

As you can see the battery capacity is the same in both scenarios, however, how long the battery lasts for changes. 

This is due to the different currents required by each LED in each scenario. 

The LED in scenario A consumes 50mA and therefore the battery will last for 10 hours.

Whereas, the LED in scenario B consumes 100mA which means it will last for 5 hours.

A 50% decrease in time. 

So, the amount of current the type of light used in fairy lights consumes, plays a large part in how long the battery will last for. 

Different types of fairy lights

Fairy lights use Light Emitting Diodes (LED’s).

But, LEDs vary in size, colour, brightness, angle of illumination etc.

Depending on the LED’s characteristic, it will draw different amounts of current. 

A smaller LED will require much less current to operate compared to a bigger one. 

Also, the brighter the LED, the more current it will draw which is going to drain a battery much faster. 

Factor #3  of how long batteries last in fairy lights: Length of fairy lights

Next on the list of factors that affect how long batteries will last in your fairy lights, is its length.

Fairy lights come in a variety of lengths from 1m, 2m, 3m, 5m and more. 

How does the length affect the battery?

Increasing the length means the number of LED’s are going to increase across the length of the fairy light.

The more LEDs are going to add to the overall power consumption (which comes down to some electronics theory). 

In a Series circuit the current supplied by the battery remains the same throughout the circuit, but the voltage is divided among the components. 

Adding more components such as LED’s is going to increase the power consumption of the overall circuit. 

We saw earlier the current capacity of a battery given in Amp-Hours, or milliamp-hours. 

But, to calculate more effectively how long a battery will last with multiple LEDs it is better to look at the battery’s Power capacity (Wh). 

To obtain the power capacity we simply multiply the current capacity of the battery by its nominal voltage. 

Say, we have a 3V battery whose current capacity is 250mAh, its power capacity will be 750mWh or 0.75Wh.

Let’s take a look at a quick example.

Below is a circuit with a voltage supply and one single LED.

To calculate how much power the LED consumes we use the power formula; P = V x I.

Giving a power value of 34mW for the LED.

The power capacity of the battery is 750mWh (3V x 250mAh).

Dividing the power capacity of the battery (750mWh) by the power consumed by the LED (34mW) gives us the value of how long the battery will last for which equals 22 hours. 

Now let’s add another LED as seen below.

The voltage and current capacity of the battery remain the same. 

But, by adding a second LED (of the same value), the overall power consumption of the battery is doubled (34mW x 2 = 68mW).
Now, when we divide the power capacity of the battery by the overall power consumption of the two LEDs, we get 11 hours.

Note, as you add more LEDs, the voltage drop across is going to increase. To combat this, you will need to increase the value of the supply voltage. 

This is why fairy lights greater than 2m (6.5ft) in length, will require more batteries. 

Factor #4 of how long batteries last in fairy lights: Quality of batteries

The quality of battery used in the fairy lights is another factor that will determine whether your fairy lights last through the night or just half of it.

Cheaper batteries are manufactured to cut down on overall cost with the end game of making more profit. 

This comes at another cost however of cheaper materials being used. This greatly reduces the overall performance of the battery which will be evident when your fairy lights turn prematurely. 

So, check the stock battery that comes with your fairy light and make sure it is a good quality, reputable brand. 

Factor #5 of how long batteries last in fairy lights: How long it is left on for

Finally, on the list of factors of how long batteries will last in fairy light, is how long you leave them on for.

This might seem like a no brainer, but it’s worth noting. 

If the fairy light is turned off after a short period of time, this going to mean that the battery will last for longer than just keeping it on when not needed.

Turning them off when not needed can extend the battery’s life for weeks.

How long do the standard batteries last in fairy lights?

As there are different fairy lights as well as batteries, knowing exactly how long a battery will last in your particular case will be hard. 

But, we can make a rough estimate of the standard batteries as well as LEDs used. 

As the length of a fairy light increases, the voltage needs to increase as well to supply the LEDs with enough current to turn them on. 

So, the longer the fairy light, the more batteries are required. 

Coin Cells (CR2032) are the common type of battery used to power fairy lights due to their sleek design. This means the battery case can be smaller making the overall setup easier to manage. 

CR2032’s are the standard brand supplied when you buy most fairy lights (if any batteries are supplied). So, I will use them for my calculations.

They have a nominal voltage of 3V and battery capacity of 250mAh.

The table below summarizes the rough estimates of how batteries will last for different lengths of fairy lights.

Again, these are all just estimates for an ideal situation. There are many variables that will affect these values.

Note, when you double the voltage of a battery (by connecting it in series), it’s battery capacity remains the same. This is why for lengths 3-5m, the number of hours decreases. 

To increase the battery capacity using two batteries, you will have to connect them in parallel. 

How to make fairy light last longer using batteries

Fairy lights are designed to be operated by batteries since they are used in applications like temporary decoration setups in weddings, parties, etc.

So, plugging them into a power outlet isn’t an option to make them last longer. 

But, fear not! There are a couple of things you can do to extend the life of your fairy lights. 

Tip #1 making batteries last longer in fairy lights: Turn them off

The first tip is the simplest so I thought I’d get it out the way and is to turn the fairy lights off.

If you do not require to run them for long periods of time, turn them off. This could extend the batteries for weeks on end! 

Tip #2 making batteries last longer in fairy lights: Use higher capacity batteries

As you now know, the higher the battery capacity, the longer that your batteries will last in fairy lights. 

The stock batteries supplied with the fairy lights might not have sufficient battery capacity, so you might have to replace them with ones with higher battery capacity. 

Remember to invest in good quality batteries as well. 

Tip #3 making batteries last longer in fairy lights: Opt for smaller LED fairy lights

There are many different styles of fairy lights available for many different occasions. 

The type of light, as well as size is going to vary. 

If you need your fairy lights to last for long amounts of time, opt for ones that use smaller sized LEDs as they will consume less current. 

Also, if you only require 3m of fairy light, do not buy one that is 5m in length. 

Benefits of using rechargeable batteries for fairy lights

You can only extend the life of batteries so much before you will have to throw them in the bin. 

Using disposable batteries is not only harmful to the environment, but is a waste of money.

Rechargeable batteries, as the name suggests, are batteries that can be recharged and used again and again.

This means that you can reuse them with your fairy lights without having to throw them out which is going to be beneficial for the environment and your bank account.

The post How long do batteries last in fairy lights? 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.

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