Guide to iPad and other Tablet Devices : Part 4
Battery Life - Never enough with a power
The dreaded dead
battery is potentially a greater problem in power hungry
tablet devices that may have much shorter battery life than
you've become accustomed to with your phone and MP3 player.
Mobile devices are becoming
more power-intensive at a rate faster than battery technology
can provide compact light batteries to power the devices.
Whereas your cell phone may
work for days, and your MP3 player for up to 20+ hours, a tablet
might have 5 - or even fewer - hours of life.
Considering a tablet's battery
life, contrasting that with how much battery life you'll need,
and understanding how to manage/extend the battery life - is
therefore a key part of determining the relative suitability of
Women might think they can
never be too slim or too wealthy (and who are we as mere men to
disagree!). Tablet owners similarly
understand they can never have too much battery life.
Tablets are by their very
nature portable devices, intended to be used without needing to
be plugged in to a power source other than for occasional
recharging. But they are also heavy users of power - the
bigger the screen, the more power required to drive it, and the
faster the processor, again the more power needed to keep it
processing, and the more the bandwidth, yet again, more power is
needed to handle the inflow and outflow of data.
On the other hand, in
theory, due to their larger size (compared to MP3 players or
phones) there is more room in a tablet device for batteries.
But tablet designers need to carefully tread a compromise
between size (and weight!) on the one hand, and battery life on
the other. Additionally, some CPUs consume greatly more
power than others, and so there is unsurprisingly a massive
variation in probable battery life in tablet devices.
Note also that battery life
will vary depending on what the device is being used for.
Some applications are more power hungry than others - watching a
video being one of the most power intensive, and 3G data
generally requiring more power than Wi-Fi data.
Note also that battery life
'estimates' by manufacturers are notoriously optimistic, and
finally also keep in mind that each successive charge/discharge
cycle slightly shortens the battery's life - another reason to
start off with as much longevity as possible, because that both
reduces the frequency with which you'll need to recharge the
battery and also the speed at which successive rechargings start
to appreciably reduce the battery life.
This of course becomes a
vicious cycle - the more the battery life shortens, the more you
need to recharge it, and so the faster the battery life
continues to shorten.
There is good and bad news
with Apple's iPad units. The good news is their battery
life is fairly generous - typically you'll get 10 hours of life
out of a charge. The bad news is the battery is sealed
into the unit; you can't swap it out and replace it with a spare
battery if it dies, and when the battery needs to be replaced,
you'll have to send your iPad back to Apple for them to replace
it for you, at considerable cost.
Most other tablets will
probably have user-replaceable batteries, and so it becomes
feasible to consider one approach to extended battery life as
being simply carrying a spare battery with you and swapping them
over as/when necessary. This also makes the eventual
replacement of a battery easier too.
Which is better? A
unit with a replaceable battery with a five hour life, or a unit
with a non-replaceable 10 hr battery? If the size/weight
and cost of a replacement battery is not too substantial, and if
changing the battery is easy and quick like in most cell phones,
I'd probably prefer the five hour replaceable battery, and would
simply carry two spare batteries with me. But you might
Standard Battery Chargers
At long last, the portable
device industry is finally and slowly standardizing on a couple
of standard connectors for chargers. These are the micro
and mini USB connectors.
You should insist on any
tablet you buy having a standard mini/micro USB connector for
power charging purposes.
Apple of course does not
have this, preferring instead its unique design multi-purpose
connector (thereby enabling it to charge a licensing fee and get
another small bit of profit any time anyone ever makes and sells
any sort of device including an Apple style connector), but due
to the market dominance of Apple, this has become a de facto
third 'standard' connector. It also has one saving grace -
at least the power cable ends in a regular USB connector at the
power charger end, so it is not quite so dependent on the type
of charger it is connected to.
However, that does raise
another issue. A typical USB port is rated to supply a
maximum of 0.5 Amps as part of the USB standard definition.
These days some will supply up to 1.0 Amps. But,
amazingly, not even a flow of 1 Amp is sufficient to
simultaneously power and recharge an iPad - it needs around 2
Amps of power in order to charge at a reasonably fast rate
and/or to operate and charge (more slowly) at the same time.
Fortunately other devices
that take their power from a USB type connector won't be harmed
if the charging device is capable of up to 2 or more Amps of
power, so all you need to simply do is upgrade the chargers you
travel with, in your car, home and office, so they are all
capable of delivering the higher rates of current to charge the
more power hungry tablet devices as well as power-sipping
devices such as phones and MP3 players.
A word of encouragement on
the battery life front, particularly for iPad owners or
intending iPad owners. There are starting to appear some
external rechargeable battery packs with a reasonable amount of
stored charge in them such as to be able to augment the battery
life of the iPad (or other tablet device).
The largest we've seen has
about 8900 mAh of capacity. The iPad has a 25 Watt/hour
battery, which is more or less the same as a battery with about
6700 mAh, so in round figures, this external battery pack
provides just over another full charge for an iPad, and who
knows how much extra charge for other tablet devices.
Generally you'd be better
advised merely to carry a second battery if the tablet allows
for easily replaceable batteries. This would be (or at
least, should be) a cheaper solution, and a battery by itself
would be smaller and lighter than this external battery pack
which comes complete with charging circuitry, plug sockets, LEDs,
and external packaging.
of a multi part Buyers Guide to iPad/tablet devices.
Please visit the other parts of this series - links at the
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30 Sep 2010, last update
21 Jul 2020
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