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Best External Battery Chargers

last updated Feb 26, 2019

How many times in your life have you been in a situation when you are using your smartphone, tablet, or any other technology devices and you get the dreaded low battery message. With a world that is so dependent on technology, it is always smart to have some device on you, not only for safety but also to keep you connected with the world when out on your next adventure. Now, how can you avoid getting the low battery message and keep your devices charged? The answer is an external battery charger. Explore our 10-product guide to help you find the perfect companion for you and your devices.

In a Hurry? The test winner after 9 hrs of research

icon
Anker Powercore 2000
97/100 our score
Effectiveness
100
Portability
98
Versatility
93
Anker Powercore 2000
Why is it better?

The PowerCore utilizes the most efficient and reliable battery cells

Features surge protection, temperature control, and short circuit prevention technology

Integrates three distinct charging technologies to deliver ultra-fast charging times

In a Hurry? Editors choice:
Anker Powercore 2000
Test Winner: Anker Powercore 2000
Researched Sources
16
Researched Sources
Reviews Considered
1,344
Reviews Considered
Hours Researching
9
Hours Researching
Products Evaluated
10
Products Evaluated
Last Updated:
By Sami Kritz:

Never be stranded again! With one of these top-rated portable battery chargers, you can always be connected. Each product on our list is unique, for example, the Mophie Powerstation is the only product on our list that is compatible with wireless charging. Check out the FAQ to learn more and don't forget to vote on which criterion is most important to you when choosing a charger!

Sorting Options
Effectiveness Portability Versatility By Default
Rank
PictureProduct
Name
Rating
Shops
#1
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
97
Effectiveness
100%
Portability
98%
Versatility
93%
Price Comparison Last Updated (22.05.19)
$55.99
#2
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
96.3
Effectiveness
100%
Portability
91%
Versatility
98%
Price Comparison Last Updated (22.05.19)
$69.99
#3
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
94.7
Effectiveness
100%
Portability
92%
Versatility
92%
Price Comparison Last Updated (22.05.19)
$59.99
#4
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
94.3
Effectiveness
92%
Portability
97%
Versatility
94%
Price Comparison Last Updated (22.05.19)
$39.99
#5
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
93.7
Effectiveness
95%
Portability
91%
Versatility
95%
Price Comparison Last Updated (22.05.19)
$69.98
#6
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
91.7
Effectiveness
96%
Portability
84%
Versatility
95%
Price Comparison Last Updated (22.05.19)
$41.99
#7
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
91
Effectiveness
95%
Portability
92%
Versatility
86%
Price Comparison Last Updated (22.05.19)
$53.85
#8
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
90
Effectiveness
91%
Portability
92%
Versatility
87%
Price Comparison Last Updated (22.05.19)
$74.96
See Deal
$99.95
#9
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
89.7
Effectiveness
94%
Portability
87%
Versatility
88%
Price Comparison Last Updated (22.05.19)
$44.99
#10
The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
89.3
Effectiveness
82%
Portability
96%
Versatility
90%
Price Comparison Last Updated (22.05.19)
$19.99
In Depth Review Top 10
  • Anker Powercore 2000
  • Zerolemon Portable
  • Aukey 3000
  • Jackery Bolt
  • Mophie Powerstation 8X
  • Mophie Powerstation
  • Lifeproof Lifeactiv
  • Goal Zero Venture 30
  • Ravpower Portable
  • Anker Lipstick
Table of contents
  • Criteria Used for Evaluation
  • Other Factors to Consider
  • Frequently Asked Questions
  • Sources

Top 10 Picks

1. Anker Powercore 2000

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
97
Anker Powercore 2000
Effectiveness
100
Portability
98
Versatility
93
best offer for today
$55.99
Pros:

The PowerCore utilizes the most efficient and reliable battery cells

Features surge protection, temperature control, and short circuit prevention technology

Integrates three distinct charging technologies to deliver ultra-fast charging times

Cons:

The four LEDs indicate how much power is left but it is quite inadequate

Anker has released some of the more impressive battery chargers to the world over the years and their PowerCore Speed 20000 sits on top. Most chargers with this type of power capacity are incredibly bulky and heavy but Anker manages to combine both perfectly.

Read more

Effectiveness
To put in perspective how much the 20000 milliampere hours (mAh) of capacity that this device is capable of actually is, this could feasibly charge the iPhone 7’s battery seven times before needing to be charged again. With dual-USB ports, this is capable of charging more than one device at the same time. In addition, Anker implemented both PowerIQ and VoltageBoost technology to deliver the fastest charge possible. Finally, this does feature Qualcomm Quick Charge 3.0.

Portability
No need to worry about the integrity of this charger as it features rounded corners and a tough plastic shell that will protect it from accidental falls and dinks. Also, it features a black casing for aesthetics. For a battery charger of its capacity, it is quite amazing how small and portable this is. In fact, for a power bank with its power, it could be the smallest ever.

Versatility
What you see is what you get here and there are not options of color, size, or wattage. However, when the quality is as high as it is here, that is certainly not a bad thing.

2. Zerolemon Portable

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
96.3
Zerolemon Portable
Effectiveness
100
Portability
91
Versatility
98
best offer for today
$69.99
Pros:

Has a capacity of 30000 mAh

The design is very rugged and can hold up to abuse

Features five USB ports

Cons:

Quite a massive device and is not going to be for everyone

This battery charger completely amplifies the amount of the previous version, with the unfortunate trade-off of portability. But, besides its massive power, it features five separate USB ports making it suitable for charging multiple devices simultaneously.

Read more

Effectiveness
With 30000 mAh of capacity, even the toughest of critics must agree that this packs a powerful punch. You could feasibly charge an iPhone 7 up to 11 times and a Galaxy S8 Plus seven times. When it comes to charging, this power bank has no equal or competition. With five USB-ports, one utilizing Quick Charge 3.0 technology, there is seemingly no limit to the number of devices you can charge. Plus, it is even compatible with the Nintendo Switch.

Portability
The external construction certainly matches the power and capabilities of this battery charger. It features anti-shock technology and has a rugged exterior that makes it suitable for outdoor use.
Unfortunately, this is the trade-off to such a powerful device. Do not expect this to be light or extremely portable as even though you can carry it in a pack, this is not ideal for light uses.

Versatility
The choice is yours from either a USB port with Quick Charge 2.0 or 3.0 technology. Clearly, the 3.0 version is a little more money.

3. Aukey 3000

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
94.7
Aukey 3000
Effectiveness
100
Portability
92
Versatility
92
best offer for today
$59.99
Pros:

Features Quick Charge 3.0 technology for faster charging

Intelligently adjusts its voltage to adapt to the specific USB device

Has built-in safeguards and advanced circuitry for maximum protection

Cons:

Displays an indicator light depending on the current level of the battery life; but, it does so within a certain percentage so you never know the actual percentage left

Despite a battery level indicator design that will leave many scratching their heads, this charger is an absolute stud capable of delivering 30000 mAh of power. In addition, integrated Quick Charge 3.0 technology ensures ultra-fast charging.

Read more

Effectiveness
This is yet another portable charger capable of holding 30000 mAh. As an example, you could charge the iPad Mini three full times and the iPhone 6s around 11.5 times. When charging your device with this charger, you have plenty of options. Either use a USB-C cable or a micro USB cable. All in all, this does feature Quick Charge 3.0 technology for the fastest charge possible.

Portability
Overall, the construction is very solid and it should hold up to tame abuse or accidental occurrences. However, as opposed to high-end manufacturers, it may not be as impressive.
Just like the previous power bank, this is not the lightest charger on the block. But, it is portable enough for you to fit it inside of your backpack or bag on your next adventure.

Versatility
There are no further seller options available for this particle external battery charger but the lone option will suffice for almost everyone.

4. Jackery Bolt

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
94.3
Jackery Bolt
Effectiveness
92
Portability
97
Versatility
94
best offer for today
$39.99
Pros:

Protects your devices from overcharging and surges

Extremely portable design that can easily fit in your pants pocket

It features pass-through charging

Cons:

If charging three devices at once, it will do so very slowly

While the Jackery Bolt Portable Charger is not going to overwhelm or overly-impress you with its capacity, it focuses more on the combination of sufficient power and portability.

Read more

Effectiveness
This is only capable of holding 6000 mAh of power. Granted this does not come close to the previous three, it is still enough power to charge an iPhone 6, 7, or 8 twice and the Plus versions 1.5 times. Due to the lightning cable that comes attached to this charger, it enables super-fast charging. Also, it sports pass-through charging which allows it to charge itself and your devices. Finally, you can charge up to three devices at once; but, doing so will result in slower speeds because its max output is 2.4 amps.

Portability
A sleek and stylish design is in order here, but it is also very practical. Jackery built this with a premium aluminum shell that not only looks fantastic but also enables fast and more reliable radiating. For portability, this is one of the best choices out there. Weighing in at just 5.3 ounces, it is lightweight and small enough to easily fit inside of your pants pocket.

Versatility
There are two versions available; both a black and orange model. However, for whatever reason, the orange version is more expensive.

5. Mophie Powerstation 8X

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
93.7
Mophie Powerstation 8X
Effectiveness
95
Portability
91
Versatility
95
best offer for today
$69.98
Pros:

Features Priority Charging which allows it to charge itself while it charges your devices

It can be used in conjunction with the Mophie Power application to monitor the battery life

Multiple capacities can be selected from

Cons:

Several users have griped about the physical size of the charger

What is truly nice about the Powerstation 8X is that Mophie provides you with multiple options for the capacity. As such, for those who do not require an insane amount of power, you can still enjoy all the other benefits of it with a smaller capacity.

Read more

Effectiveness
Indeed, you are able to choose the capacity that you desire. If you know you want the absolute most it can dish out, go for the 15000 mAh version. However, to save money, you could also settle for 4000 mAh of power. This is designed for those who need to charge more than one device at once. It features dual-USB ports and that means it can handle two devices at the same time if the situation calls for it.

Portability
Only premium materials were used to construct the Powerstation 8X. This includes a high-performance aluminum finish that conceals the power that lies beneath it. In terms of the physical size, this is not the smallest device in the world. Some users have taken issue with this but even so, it certainly is not the worst in terms of portability with a weight of 13.6 ounces.

Versatility
As you already know, you can choose the capacity you desire. Past this, you can select different colors including gray, gold, green, and aluminum.

6. Mophie Powerstation

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
91.7
Mophie Powerstation
Effectiveness
96
Portability
84
Versatility
95
best offer for today
$41.99
Pros:

Features pass-through charging

It is compatible with Qi and various other wireless charging technologies

You can view the current battery life with a simple push of a button

Cons:

Does not feature Qualcomm Quick Charge

Not that heavy but very bulky

One of the bigger advantages of the Mophie Powerstation is that it supports Qi devices. As such, if you possess devices with Qi technology you can wirelessly charge them in conjunction with this charger.

Read more

Effectiveness
10000 mAh of capacity means that you can charge, feasibly, any device that you have. In addition, as a bonus, the battery delivers an additional 48 hours of power. This is another model that is missing Qualcomm Quick Charge but the technology that is present makes up for it. Clearly, the biggest is the ability to charge Qi devices wirelessly. While doing so, you can then charge another device with the USB port.

Portability
If you are familiar with Mophie, the physical design of this device may surprise you. Instead of being sleek and aluminized, it is rather bulky with a rubberized finish. It is not as if the Powerstation is that heavy, at only 8.52 ounces, it is just the makeup is bulky; making it difficult to easily transport at times.

Versatility
All across Amazon, there are different variations of the Powerstation; both of different capacities and colors.

7. Lifeproof Lifeactiv

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
91
Lifeproof Lifeactiv
Effectiveness
95
Portability
92
Versatility
86
best offer for today
$53.85
Pros:

Features quick charge technology

Backed by a one-year limited warranty

The built-in LED lights can also be utilized as a flashlight

Cons:

Only features one USB port

With an efficient combination of capacity and portability, the LIFEACTIV Power Bank is an ideal choice for everyone. Unfortunately, it is limited in one respect and that is it only sports one USB port.

Read more

Effectiveness
When this charger is at maximum capacity, it holds around 10000 mAh of power. This is enough to keep your smartphones, tablets and any other devices running strong for your next trip. The integrated technology here is stellar and it includes auto-stop charge technology that will save battery life for later, quick charge capability and rapid recharge times to speed up the charging process. However, many will be disappointed with the only the lone USB port.

Portability
This is truly suitable for any type of weather conditions that you can fathom as it is waterproof, dirtproof and even snowproof. To top it off, if you accidentally drop it than it is built to withstand that, as well. In terms of weight and physical size, this is a fairly average battery charger. There are versions much bulkier, while others are smaller; making it adequate in this category.

Versatility
The black version available on Amazon is really the only variation that you need, as it is highly-capable as it is.

8. Goal Zero Venture 30

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
90
Goal Zero Venture 30
Effectiveness
91
Portability
92
Versatility
87
best offer for today
more shops
$99.95
$74.96
See Deal
Pros:

You can either charge it via USB or from the sun (with the optional Nomad 7)

Has an IPX6 weatherproof rating and is suitable for bad weather

Features a case that is very rugged

Cons:

Can take a long time to charge, especially if using the solar panels

Some have stated it is a bit too heavy

As opposed to the other battery chargers on this list, the Venture 30 is actually capable of charging itself via solar panels. While not mandatory by any stretch, this allows for a convenient way to charge the device back up when it loses power.

Read more

Effectiveness
The raw power of the Venture 30 is not going to overly-impress you. At just 7,800 mAh, it may not be quite the capacity that high-end users are seeking and desiring. Most notable here is the ability to charge this device via the use of solar panels. With the optional Nomad 7 solar panels, you can use the sunlight to build up the voltage. Plus, there are dual-USB ports for simultaneous charging.

Portability
For those who are not careful with their technology devices, this is for you as it is built to withstand a decent amount of abuse. With a rugged exterior that features an outer trim and waterproofness, it can take it. For just the charger, not including the solar panels, it is easily packable and not too bulky. Clearly, this will alter if you invest in the Nomad 7, as you will have to carry the solar panels along as well.

Versatility
It is not mandatory, but you can bundle the Nomad 7 solar panels with your purchase.

9. Ravpower Portable

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
89.7
Ravpower Portable
Effectiveness
94
Portability
87
Versatility
88
best offer for today
$44.99
Pros:

It automatically adjusts to the correct voltage setting for your connected device

All three ports support pass-through charging which allows the charger to charge itself while charging external devices

Can hold 26800 mAh

Cons:

Several complain about the immense size and weight

Does not support Qualcomm Quick Charge

There is no doubt about it, the RAVPower Portable Charger is a beast. Possessing the capability of holding 26800 mAh and charging three devices simultaneously, this is an ideal choice for those seeking power for long trips.

Read more

Effectiveness
Due to the immense amount of power this charger can hold, 26800 mAh, it is highly-capable of charging any device you can imagine. For most smartphones, you could feasibly charge them six times over. On all three 2.0 USB ports, meaning it can charge up to three devices at once, there is pass-through technology which allows the device to charge itself while doing so for your devices. However, it does not support Qualcomm Quick Charge technology.

Portability
To keep the exterior looking stylish and classy, for those who care about this sort of thing, a matte black finish has been applied. In addition, it is also an anti-scratch coating. It is convenient that a carry pouch comes included with your purchase as this charger is simply too massive to fit inside of your pocket. At just over one pound, it is better reserved in your carry-bag.

Versatility
If black does not appeal to you, or you are an Apple enthusiast, there is also an option for a white-colored version of the exact same external charger.

10. Anker Lipstick

The rating is based on the average rating (1-100) from all the criteria in which we rated this product.
89.3
Anker Lipstick
Effectiveness
82
Portability
96
Versatility
90
best offer for today
$19.99
Pros:

With a one amp adapter, this can charge in less than four hours

It is designed to be taken anywhere and is ultra-portable

Includes a LED indicator light for the battery life

Cons:

There have been some reports of overheating and efficiency issues

For those looking for the most portable battery charger out there, look no further than this model with its literal lipstick design. However, for such a small device, it packs an impressive power capacity of 3350 mAh. If not for various reports of overheating issues, this could have easily climbed higher.

Read more

Effectiveness
Now, 3350 mAh of power may not sound like that much and granted, it really is not. However, for its size, it is a fairly impressive amount. While not as capable as others, this lipstick charger does feature high-speed charging and will detect your device to deliver the best charge possible.

Portability
Being only crafted from premium materials, you are guaranteed a long-lasting charger. Its aluminum-alloy chassis and scratchproof coating will hold up to moderate abuse. No doubt, this is where this charger shines the brightest. It can easily be tucked away in your pocket, purse or any place you can imagine. It really is that small (it is practically the size of lipstick).

Versatility
A few color options are at your disposal including blue, pink, golden, silver and black.

Criteria Used for Evaluation

Effectiveness

The Raw Power and Maximum Capacity
From one battery charger to the next, the maximum capacity it can hold is going to vary; there is no doubt about that. But, what exactly signifies the total power that it holds? Most commonly, you will either see the power be represented by ampere-hours (Ah) or milliampere-hours (mAh). For the most part, you will see the latter more than the former. In case you see it labeled in Ah, know that for each 1 Ah of power, it is 1000 mAh (hence the “Milli”). However, what does this mean to the average person?
This number describes the energy charge that a battery can hold and in other instances, how long a battery will last before it needs to be recharged. For external battery chargers, it is more about how much power this will hold. Of course, still, this number may be foreign to you and it still may not easily represent how much energy the charger has. As such, manufacturers typically give an example of how much power their charger has. For example, 20000 mAh could charge an iPhone 7’s battery seven full times. Just know, the larger the number the better.

Its Charging Capabilities and Integrated Technology
Raw power is one design feature altogether, but the technology and its capabilities are two entirely different aspects. For starters, an extremely important detail for some is how many devices the charger can provide voltage to simultaneously. This is either done with a USB, micro-USB or wireless technology (such as Qi). But, it all depends on how many options are present for you; some will have multiple USB ports and the Qi compatibility. However, some will only have one USB port. Question is, how many devices are you looking to charge at the same time? In addition, the max output also plays a role as charging multiple devices at once could slow it down quite a bit.
Also, two huge technologies to look out for are pass-through charging and Qualcomm Quick Charge. The former allows the device to charge itself in conjunction with charging the devices you connect to it. However, note that if you do this all the time it will reduce the battery lifespan over time. Meanwhile, the latter, as the name suggests, speeds up the charging time for your convenience. After all, when you need your device, you do not really want to wait an infinite amount of time for it to reach full capacity.

Portability

The entire purpose of external battery chargers is to provide you with a feasible means of charging your devices when you do not have access to another method. So, nine times out of ten, you will use this device on the go or on a trip/vacation. Thus, portability is also going to play a vital role and this is where it can get a tad complicated. Most of the time, the capacity and power will play a role in the size. There are exceptions (such as the number one charger on this list) but typically, those capable of 30000 mAh of power or above are going to be quite heavy and bulky. Still, they could be stuffed inside of your backpack or travel bag. But, they may not be feasible for short trips where you are looking to travel as light as possible.
Hence why the smaller capacity battery chargers can be better for some as they will probably be more portable (such as the last charger on this list). What is more important, capacity or portability? If you want something that is super portable (maybe even small enough to stick in your pocket), you may have to sacrifice some power.

Versatility

While not the most important factor to consider, it is still worth bringing up the different seller options that are provided to you. For example, manufacturers may offer their battery chargers in different capacities or colors. If you really fall in love with a specific charger but it does not have your initial desired capacity, having further options could prove to be beneficial. The same concept applies to colors, even though that is solely for aesthetics and preference. Also, it could be as simple as spending a few extra dollars for a specific type of port (for example a 3.0 instead of a 2.0).

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Most Important Criteria (According to our experts opinion)
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Charging the Charger

Keep in mind that a lot of these portable chargers take a while to charge themselves. There is a lot of power built into these small machines and they need a lot of juice if they are going to be charging your smartphone 10x without a boost.

Weight

It is also important to take a look at the weight of the charger. It you plan to carry the charger around in your purse while site seeing, a 6 pound charger may be a bit too heavy. A downside to lightweight chargers is the fact they tend to hold less power, but are more portable.

Other Factors to Consider

Materials

So far, it has all been about the charger’s ability to charge your devices. Granted that is their design purpose, there is more that goes into it. Take, for example, how well the exterior is designed and constructed. In terms of external workmanship, it really is not about how pretty or stylish it is, but more so its ruggedness and ability to withstand abuse and harsh conditions. First off, let’s address its ruggedness. Now, ruggedness does not have to equate to bulkiness. Instead, what type of materials are used to construct the charger? Some examples could be a premium aluminum shell or a rubberized finish that will withstand drops. Also, how about the finish? Is it scratch-resistant? These small details do play a role.
However, are you looking to utilize the charger in any weather conditions? If so, you may want to prioritize those that are waterproof or at least water-resistant. In this instance, if the charger becomes exposed to the bad weather it would not become damaged or compromised.

Frequently Asked Questions

q: Will charging a smartphone with a portable battery charger damage its battery?

a:

Here is the reality of the situation, no matter their designed purpose, some people still question whether or not their battery will be safe when it is charged from a portable battery charger. Especially, when it comes to their smartphones. Perhaps, people are simply overprotective of their phones are maybe they have a legitimate concern. Well, the battery in your smartphone will not be damaged when it is charged via this method.
However, if you do ever have concerns over this and refuse to think otherwise, you can look for portable chargers that feature smart circuits to detect the device and charge it accordingly. This way, your mind can be at ease and you can move on from this slight phobia.

q: Are external battery chargers allowed on planes?

a:

This could be the most common question of them all and it is one that everyone seems to have. Chances are, you may be interested in transporting your battery charger via an airplane. But, can you? As everyone knows, airlines have tight and strict regulations that you must abide by. However, you can fly with them with some minor exceptions. Come on, you did not think it would be that easy, did you? Here is the deal, if the battery charger utilizes lithium-ion batteries than it can only be stored in carry-on baggage only. Also, if it happens to be over a certain amount of watt hours then it may not be allowed at all.
While these devices are typically displayed in milliampere hours, the Federal Aviation Administration restricts lithium-ion batteries in terms of watt-hours. Anything above 100-watt-hours will be restricted. To find this amount out, there is an algorithm that you can use. For an external battery charger, take the milliampere hours and divide it by a thousand and then take that number and multiply it by the nominal voltage. Thus, giving you the watt-hours.

q: What charges the battery charger itself?

a:

Alright, so it has been stated over and over again that these devices are used to charge your devices. However, what exactly charges the battery charger itself? After all, it does not magically create the voltage from the air. Nope, just like anything else, to power it up you have to manually do so. Do not worry, this is not rocket science and it as easy as it is to charge your devices. Most of them will come equipped with a micro SF connector that will plug directly into a USB port. Now, you can either get a USB-to-wall adapter or simply plug it into a USB port.
It may be easier to go with the former method as the electricity provided from an outlet may prove to be more beneficial.

q: Is it safe to leave the charger in a hot location?

a:

There has probably been a time in your life where you accidentally left an item of yours in the scorching hot car that has been sitting in the sun for hours. Depending on what it was, it could have ruined it or damaged it. But, would this happen if you left an external battery charger in your car at extreme temperatures? Well, let’s just say this, it is not advised to do so for any electronic device you have as it can provide harm to them. Especially, given that most manuals will specifically state not to do so.
To take this question a little further, how should you store them? The recommended temperature for most batteries is around 60 degrees Fahrenheit. Clearly, if you store them in a room that is a few degrees off it is not going to damage them. But, be sure to avoid extremely low or high temperatures. Also, try to store them in a dry location.

q: Will the battery life drain over time?

a:

Even if you are completely ignorant about batteries, you may have questioned their lifespan before. In specific, if or if not, they were losing juice over time by merely sitting around. Guess what, if you concluded that they were then you were spot on correct. However, depending on the type of battery, it will vary. The reality is, batteries self-discharge over time and this will increase as they get older and if they are exposed to elevated temperatures (another reason to store them properly). Remember, these devices are essentially one big battery.
Lithium-ion, in specific, will self-discharge around five percent in 24 hours and over a month, around one to two percent. Not too bad, all things considered

q: Can you charge a laptop with a USB port?

a:

Some may be wondering how on earth this question is relevant to the topic at hand. Well, coming into this guide, you may have wondered if laptops could be charged with this type of battery charger. And, most of them charge with a USB port. As such, this question is presented and it is a good one to be knowledgeable of. Anyone who knows a thing or two about computers probably already knows this answer but for those who do not, no, you can’t charge a laptop via a USB port. Why?
Computers are designed with USB ports but they are not meant to charge themselves. Instead, they are used to power peripherals (keyboard, mouse, etc.) and also external devices such as music players and iPods. So, if you wanted an external battery charger to perform this task, you would need a power solution that is meant to be plugged into the power port of a laptop (which is not the USB port).

Sources

  1. Jason Hidalgo, How to Choose a Portable USB Charger and Battery Pack, Buying Guide
  2. Simon Hill, The best portable chargers of 2018, Digital Trend Website