A lot of people have problems with keeping their mobile
devices charged. Tablets aren't too bad,
unless they're playing a lot of video or streaming data. Mobile phones can drain really quickly,
especially if they're being used in remote regions or inside buildings, where
mobile coverage is cutting in and out frequently.
The simple solution is to always keep a wired charger
handy so you can plug into the nearest wall outlet. But what if there are no outlets around? This can happen frequently, for example:
- Hiking, or camping in remote areas.
- At sports event.
- In some bars or restaurants.
- At some airports or train stations.
Those are just a few examples. The simple solution is to buy a "power
bank." A power bank is essentially
a portable battery, which you can use to re-charge your mobile device.
A power bank will generally charge devices that can be
charged over things like USB cables, but can't charge items that plug into a
household outlet. So for example, you
can usually charge tablets, phones, mp3 players, and some GPS units. You can also charge a small number of
cameras, such as GoPro cameras. Some
tablets, most cameras, and laptops require a wall plug, so a power bank isn't
going to be helpful for these pieces of equipment.
On that topic, let's look at some specs. Most items that are 5 volt can be charged by
a power bank, not specifically because of the voltage, but just because devices
with 5v usually have the proper charging connections that can be taken
advantage of. Some tablets and many
cameras range from 8 volt to 12 volt, and can't necessarily be charged. Laptop computers generally accept between 12
volts and 24 volts. The charger on the
laptop is actually a step-down transformer to convert 110/120v or 220/240v into
the proper voltage for the laptop.
Power Banks are essentially batteries. You charge them, then they hold this charge
until you drain it by moving it into another device. In fact, you can say that a power bank IS a
battery, technically speaking. In fact,
the innards of a power bank sometimes are one big battery, or a bunch of
smaller batteries connected to each other.
There is a small portable battery called an 18650 that is commonly used
in Asia to provide the storage capacity inside a power bank. A couple or several 18650's are wired
together inside the power bank, depending on the size and capacity of the power
bank. By the way, this isn't necessarily
a good thing, as we'll find out in a minute.
The guts of a power bank are usually lithium ion or
lithium polymer storage. Lithium ion is
a liquid electrolyte. Lithium polymer is
a solid polymer electrolyte. What's the
difference? Lithium polymer, or
LiPolymer, is generally better. It can
have a flexible size and dimension. It
producers less heat, which means that it's more efficient and safer. It has a lower self-discharge rate. The storage capacity decays more slowly. The only real drawback about using LiPolymer
instead of Lithium Ion is that LiPolymer is more expensive. That's the reason Lithium Ion batteries
(18650's) are less desirable. You may
find that some no-name power banks are just a bunch of old 18650's that have
been recycled, not necessarily even fresh new batteries!
The health of your phone battery decays over time. That's why a new phone can generally hold a
charge longer than when the phone starts to get older. You could say that if a phone's battery
health is at 80%, its charge can only last 80% as long as it would have when
the battery was new.
As you're moving energy around from item to item, some of
it is lost either as heat or due to inefficiencies in the conversion process. This is important when figuring out how much
a power bank can help you. We'll get
into that in a minute.
Here are some of the specs that you should look for in a
good power bank:
- What is the number of mAH? This stands for milliamp hours. Ideally it should be at a voltage of five
volts.
- Can the power bank charge and discharge simultaneously?
It could be frustrating to have a power bank that will not charge another
device while it is itself charging. Some
power banks will both charge internally and charge an attached device if the
power bank is itself plugged in and charging.
Other power banks won't charge the attached device until the power bank
itself is unplugged from the wall. And
finally, some power banks, if plugged in and attached to a device that they are
charging, will let the power from the outlet pass through and charge that
remote device first, before the power bank itself starts to charge up.
- How many output ports are there? Can two devices be charged simultaneously?
- What is the output current rating? A higher number is generally better.
Your biggest question when
looking for a power bank is probably something along the lines of, "How
many times will it charge my phone?"
Is there a simple way to figure this out? Well, sort of. But the formula isn't perfectly simple.
Some power banks have very low
capacities, with rated capacities listed as probably under 4000 mAH. These are no good. They probably have one or two 18650's inside
them, and might barely provide a single charge for a typical phone.
Some power banks have very high
listed capacities, like 40,000 mAH and higher.
It seems that a lot of these are actually scams. There are some that are legitimate, but a
power bank would generally have to be fairly large to have that capacity, not
the sort of thing that would be the size of a deck of cards, and convenient to
carry around.
Other power banks have
capacities of perhaps 8,000 to 15,000 mAH.
In my limited experience, these tend to be the best ones. They're probably a branded model, and the
numbers are more likely to be accurate.
You best bet, however, is to double-check by doing a google search for
reviews on the exact brand and model of the power bank you're looking at. Luckily, a lot of people who have bad
experiences with a particular purchase will post the info on the internet,
which can prevent other people from being ripped off.
Some power banks have internet
circuit protection. This is
important. If you have something without
circuit protection and it gets connected to the wrong thing, it's pretty easy
to hurt the internal batteries so they die or become extremely weak.
Let's say that you have a phone
that has a 3,000 mAH battery. Let's also
say that you have a Power Bank that stores 12,000 mAH. You've probably already come up with a very
good question … can you just divide these numbers to come up with the amount of
times that your phone can be charged by the power bank? In other words, can your power bank charge
your phone exactly four times?
This is good logic. It's also moderately correct. The only problem is that you have to factor
in the phone's battery heat, and the conversion rate.
Let's say that your phone is
getting older and it's only about 80% healthy.
The problem is that there's no exact scientific way to measure this for
the average consumer, so it's a guess.
You can probably figure it out roughly from experience after charging your
device several times.
Also, let's say that 15% of the
stored energy is lost in conversion.
That means that only 85% of the stored energy in the power bank will
make it to the battery of the device being charged.
After considering these two
adjustments, the correct formula for figuring out roughly how much your power
bank will charge would be:
Storage of Power Bank *
Conversion Rate * Phone Battery Health / Phone Battery Capacity
Or in this example: 12,000 * 0.85 * 0.80 / 3,000 = about 2.72
times. Nearly three full charges.
As I said, this is a rough
equation, but by guessing the approximate phone battery health and conversion rate
to temper your expectations, you're going to get a more accurate assessment than
by using impossible "perfect case" results.
A lot of the cheap no-name
power banks made in Asia are sketchy.
Many are cheap and use old recycled batteries. A new 18650 is supposed to have a charge
cycle of 300 charges before it's essentially useless. However, if an unscrupulous vendor builds a
bunch of power banks with old used 18650's, you might not get very many charges
out of it before it dies. Also, there
have been occasional cases of someone buying what feels like a hefty power bank
that must have quite a bit of storage capacity, and it's only got one or two
18650's and a bag of sand to tricky people.
Try to look for something that appears to have a brand name, at the very
least! And look for detailed specs. The specs may be a lie, but if they're
detailed and look legitimate, there's maybe a slightly better chance that
you're getting a product that isn't a sham.
I did a short video to show you
a power bank that I purchased. I got
lucky, this one turned out well. I don’t
think it's in production anymore because it's been replaced by a 13,000 mAH
model, but the exact specs of mine are as follows:
- IntoCircuit Power Castle
Series
- Model PC11200
- 11,200 mAH, 5 volt
- Can charge two devices
simultaneously
- Has internal protection for
under/over current/voltage
- Does not come with a charger,
must use the charger for your phone or other device
- Only cost about $30 Canadian
plus shipping from Amazon
Like I said, it's worked
decently for me. I did some tests on
recharging my Nexus 5, which has a 2300 mAH battery. Starting with the power bank at 100% and the
phone at 0%, it took 108 minutes to charge using the 2.1amp line, which drained
the power bank to 63% of its charge.
Using the 1.0amp line, it took 137 minutes to charge the phone, but it
only drained the power pack to 83%. I'm
optimistic that by using the lower amperage line, I could probably get at least
four and maybe almost five full charges out of the power bank, if it hasn't
been sitting around for too long (your power bank, like any battery, will
slowly lose its residual charge if it sits for an extremely extended time
period).
Here's the video about my own
power bank:
One last important
consideration is that most airlines do NOT allow you to have power banks or
other significant amounts of batteries in checked baggage, unless they are
actually in a device! So a battery
inside a camera inside your luggage is fine, but a spare battery is not. Therefore, remember that you will be forced to
carry your power bank as a carry-on item!
Also, many airlines have regulations on the number and capacity of
batteries that you can carry. This
probably won't be an issue, because it's a pretty generous allowance. For example, several airlines won't let you
have batteries over 160 aH (160,000 mAH).
But this is the size of a truck battery.
Many airlines also have rules like "maximum of ten lithium
batteries per person in your carry-on, and any lithium batteries in checked
baggage must either be installed in a device, in the original packaging, or in
a carrying device that insulates the battery terminals." Check the rules in advance for your
particular airline if you're going to fly somewhere!
I'll wrap this up with a list
of the battery capacities for a number of phones that are commonly available
today. I'm sure this list will be quite
out-of-date within 24 months, but at least it'll give you a general idea of
typical battery capacities:
1810 mAH – iPhone 6
2915 mAH – iPhone 6 plus
3220 mAH – Samsung Galaxy Note
4
2800 mAH – Samsung Galaxy S5
3100 mAH – Sony Eperia Z3
3900 mAH – Motorola Droid Turbo
3000 mAH – LG G3
2600 mAH – HTC One M8
2420 mAH – Nokia Lumia Icon
2400 mAH – Amazon Fire Phone
2300 mAH – Google Nexus 5
2100 mAH – Blackberry Q10
1800 mAH – HTC Windows Phone 8X
I'm Jonathan Clark, known online as DJ Bolivia. Do you want to learn more about DJ'ing and music production? If so, visit:
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