Rail External Battery System
A great way to add extra battery life to your
iPhone and other devices
The Third Rail Battery
System comprises a case for an iPhone 4/4S and separate
batteries that can be mounted on the case or used by
Battery technology is failing
to keep up with the new power demands made of it by each
successive new model of cell phone, and so smart phones struggle
to offer good battery life.
This is particularly a problem
with Apple's iPhones, because you can't swap batteries over in the
middle of the day. The only way to add to your phone's power
charge is with some sort of external battery.
Here is one of the most elegant
approaches to solving this need, which works not only for the
iPhone 4 and 4S, but also for many/most of your other portable
electronic devices too.
Third Rail Battery System -
What You Get
The Third Rail Battery
System comes attractively packaged in an easily opened box.
Inside is a case into which
you fit your iPhone 4 or iPhone 4S, a separate battery, two
different connector cables, and a helpful well written short
There is no charger supplied
with the unit. But that is more a blessing than a
disadvantage, because the unit can be charged from any standard
USB type charger, and you probably have more of those than you can count,
already. It is great not to have another device which
requires its own dedicated charger due to having nonstandard
The unit comes with a 30 day
money back guarantee, and a one year warranty. Both are
generous and better than industry averages.
The complete 'system' - ie a
case for an iPhone 4/4S and a battery, retails for $89.99.
You can also buy cases by themselves for $39.99 and batteries for
$59.99. Indeed, if you should lose the connector cables, you
can buy them too ($9.99 each).
The products are available
through Third Rail's
website. They can also be purchased through Amazon.com
(and Amazon will probably save you the shipping costs).
Third Rail Battery System - What
1. In its simplest form,
this is a wonderful way of carrying additional recharge power for
2. But - and it is a
good but - the Third Rail system does a lot more than just
recharge a dying/dead iPhone battery. It has an external
power socket that can be used to then charge any other typical
mobile device (ie anything that uses a 3.7V LiIon type battery for
power, and which can be charged from a USB socket).
It won't charge high power
devices such as laptops or large tablets (eg iPads) but anything
that uses the standard USB and 500 mA of charging current can be
powered from a Third Rail Battery.
3. Unlike most other
external power case solutions for iPhones, the Third Rail system
uses a detachable battery. So you can have two batteries for
the one case, giving you even more emergency power (and saving you
hassle, space, weight and money compared to having to carry two
4. Not only can you have
two batteries and one case/phone, you could also have two phones,
two cases, and one battery.
5. If your entire office
(or household) uses iPhones, you could have multiple cases and
multiple batteries, and simply rely on the intelligent charging of
the Third Rail batteries to ensure that whenever you needed a
charged battery, there was always one available.
6. Multiple batteries
can be stacked together. They intelligently 'talk' to each
other and manage their power so as to consolidate the most power
in the fewest number of batteries - so rather than having maybe
five or six half charged batteries, they concentrate all their
power into two or three fully charged batteries.
They also intelligently charge
themselves so that the most full batteries get topped up first,
meaning you get fully charged batteries, one at a time, sooner
than if they were all charged concurrently.
In total, this is a
tremendously flexible system that can be mixed and matched to give
you exactly what you want, without requiring you to over-buy
things you don't want. Not only is it flexible, but it is
also very simple, with the intelligence being built into the Third
Rail system rather than being required of you, its
About the Third Rail System
There are two components to
the Third Rail System - the case and the battery. Yes, there
are connecting cables too, but they are of lesser importance.
The first step is probably to
put your iPhone 4 or 4S into the protective case. This is a
very slim case that fits around the back and four sides of the
iPhone, leaving the front open. An iPhone 4/4S measures
about 2.3" x 4.5" and is 0.4" thick. Adding the Third Rail
case increases its external dimensions to about 2.45" x 4.9" and
its thickness up to 0.46" - not very much more.
As for weight, the case adds
less than an ounce (0.85 oz to be precise) to the weight of the
phone (which is 4.9 oz to start with).
These dimensions are similar
to most other iPhone cases (although iPhone 'bumpers' are a little
The case has an Apple
connector which slides into the connector on the phone, and
duplicates the connector outside the case, but in the form of a
standard micro-USB connector rather than a proprietary iPhone
connector. But - fear not. You can still connect your
iPhone to a charger or to iTunes via your computer through a
regular micro-USB cable and the micro-USB connector on the bottom
of the case; you never need to take the phone out of its case to
use with a dedicated iPhone cable.
That too is a benefit - it
reduces the number of different types of connecting cables you
need to travel with and keep close to you.
Also on the bottom of the case
is a slide switch. Slide it one way and you see an orange
dot, which indicates that the Third Rail system is 'off' (just
like the orange dot on the iPhone's mute switch indicates when the
volume is off). Slide it the other way and that means the
Third Rail system is active and ready to transfer power into the
On the back of the case is a
connector onto which the external battery can be clipped.
The Third Rail battery is a
separate small device. It measures 3.3" x 1.8" and is about
0.3" thick, and weighs a mere 1.4 oz. You could fill your
pocket with half a dozen or more of them if you chose to do so,
but there is little reason to carry more than one or perhaps at
the most two.
On one side are four connectors
to clip the battery to other batteries or to a case, plus a 'male'
power connector. On the other side are four slots to receive
connectors from other batteries being stacked on top, and a female
On the bottom are two sockets
- one to receive charging power in from an external charger, the
other to give charging current out to other external devices.
There is also a five element
LED on the bottom and a 'press to test' button; when you press the
button, the LED reports on the level of charge in the battery.
The battery stores about 1250
mAh of power, slightly less than an iPhone's internal battery
(which is about 1400 mAh). But see below for a surprising
discussion about how you actually get more life out of 1250 mAh
than you do out of 1400 mAh.
Using the Third Rail System
Using the Third Rail System is
easy. If your phone needs a top up charge, put a battery on
the case and turn on the charge button.
When the topping up is
complete, turn off the charge button (or simply remove the battery
from the case back).
You can leave the battery
connected to the case all the time. I've tried it both ways
- with battery left on and with battery off. If you want to
keep your phone as slim as possible (eg in a dress shirt pocket)
you'll probably want to keep the battery off the phone when you're
not using it. But if space isn't quite so critical, you may
as well leave it on, making the battery harder to lose.
If you have an external
charger, simply connect it to the connector either on the battery
or on the case. Either which way, it will first charge the
phone's internal battery, and then secondly charge the external
battery (or multiple batteries if they are stacked together).
Third Rail recommend you
connect an external charger to the socket on the case, because if
you do this, it will charge at a slightly faster rate. But
apart from shaving a few minutes from the total charging time,
there is no real other difference.
If you have another mobile
device that also needs topping up, simply connect its charging
cable to the USB output adapter cable that came with the Third
Rail system. It doesn't matter if the battery is on a phone
case or not, either which way, it will start to charge the new
Multiple Battery Bricks
One of the very clever
features of the Third Rail design is that the batteries can be
stacked on top of each other, creating a larger capacity
These stacks of batteries can
be created almost without limit, stacked as high as you wish, but
Third Rail recommend between six and ten batteries per stack
is probably enough for most purposes.
When batteries are stacked,
they concentrate their power in the fewest number of fully charged
batteries, so that even if you don't have a charger with you, you
can pool the power in several partially charged batteries to get
some fully charged batteries, avoiding the need to carry multiple
partially charged batteries with you.
How 1250 mAh Lasts Longer than
Although these external
batteries have slightly less capacity than the internal iPhone
battery, the surprising reality is you can get more benefit and
usage from them than you can from the internal battery.
This needs to be explained.
So, here goes :
With the iPhone's battery, the
chances are that whenever you go somewhere with the phone, the
battery is not at 100% to start with. Maybe it is at 90%, or
some other partially full charge. So you start off with less
than the full capacity of the battery.
And when the battery starts to
drop down to 20% or less, you start to get really panicky and stop
using the phone freely, limiting its use only for emergencies.
So the actual 'comfort zone'
of usage is maybe only 70% of the full battery charge, in other
words, 70% of 1400 mAh, which is just under 1000 mAh.
But with the external battery,
you can fully charge it up to 100% of power, and then when you
choose to use it, you can fully transfer the entire 100% of its
charge into the iPhone. Apart from some efficiency and
transfer losses, you are otherwise getting the full 100% of the
1250 mAh as practical, 'comfort zone' usage.
Because the Third Rail Systems
can either be bought as complete systems or as separate
components, it is possible to come up with different mixes of
batteries and cases to reflect the situation you are in.
For example, in an office with
a dozen sales reps, maybe they only need to have six or eight
batteries - the reps only grab a battery when leaving the office
to go out on sales calls.
On the other hand, if you are
a single user, maybe you want to have one case but two batteries,
so you always have a fully charged one plus a spare to be in use.
Any other combination of cases
and batteries can also be used for whatever circumstances apply.
And, if you should lose a battery (or case for that matter, too)
you can simply buy just the battery or case as needed rather than
needing to buy a complete new system.
The Third Rail System is a
brilliant example of a very well thought through product that has
a great deal of flexibility and bonus functionality, way in excess
of that normally found in a simple, single application,
external/emergency battery for an iPhone.
It is easy to understand and
use, compact, light weight, very useful, and fairly priced.
A complete system is
$90, available either
direct from the manufacturer or from Amazon.com
probably get it quicker from Amazon, and probably get free
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4 Nov 2011, last update
02 Jul 2017
You may freely reproduce or distribute this article for noncommercial purposes as long as you give credit to me as original writer.