From the juice pack manual on Mophie's website: https://www.mophie.com/v/vspfiles/assets/images/juicepack-air-iPhone4-manual-eng.pdf
and be sure to register for their 1-year warranty per below.
Charging your juice pack air
Connect the juice pack to a power source using
the micro USB cable that came with your juice
pack. The USB cable can be plugged in to your
computer or any “Made for iPhone” wall-plug
style power source with USB out including the
standard iPhone USB wall adaptor. (The LEDs
located on the back of the device will blink
when charging, as the juice pack becomes
more charged the LEDs will indicate how full
it is, but one LED will remain blinking until
The juice pack air comes charged and ready to
go, but after the initial use, normal charging
will take only 2 to 3 hours for maximum power
– AND you can then charge it while the iPhone
is inserted or separately.
Charging your iPhone 4 using the juice pack air
If your iPhone is drained of power or if you want
to extend the battery life of your iPhone, simply
slide the iPhone into the juice pack air. Make
sure that the pin connector is securely inserted
into the bottom of the iPhone and the switch is
turned On (green). When the iPhone recognizes
the juice pack, a battery symbol will appear on
the screen and you will hear a chirp from the
iPhone, this indicates that the iPhone is
charging and/or using the power from the juice
pack rather than from the iPhone itself.
If your iPhone is drained of power, the juice
pack will first charge your iPhone. If your iPhone
is fully charged, the juice pack will act as your
primary battery and no power will be lost from
the iPhone internal battery until the juice pack
is depleted. So you keep on talkin’, rockin’,
surfin’ and sendin’!
Checking the status of the juice pack air
You are always in the KNOW! To check the
battery status of the juice pack, press the
button located on the bottom of the device.
When pressed, the LED lights will illuminate for
several seconds. Four LEDs means that the
juice pack is fully charged, and one LED means
that it is almost empty.
If you’d rather use your internal battery and
not the juice pack, use the switch on the
lower-left corner of the juice pack, to put it into
stand-by mode. The dot near the switch will
indicate whether the juice pack is in stand-by
mode (red) or charging mode (green). When
your internal battery is low, simply flick the
switch On and your iPhone will begin charging
*Note: Using the stand-by switch will give you
even more total battery life, as the iPhone uses
additional power to be on a constant charge.
Sync with your computer without removing
While connected to the juice pack air, you can
still sync your iPhone with a computer. Simply
connect the included micro USB cable from the
juice pack air to the computer and sync your
iPhone the same as if it was directly connected.
To keep your juice pack air operating to its
fullest potential, make sure to do the following:
1. Keep your juice pack dry and away from
moisture and corrosive materials.
2. Do not wash the juice pack with harsh
chemicals, soaps or detergents. Just wipe the
case with a soft, water-dampened cloth. Wipe
the pins gently with a soft, dry cloth.
3. Re-charge your juice pack once every three
months when not in use, and remember to
charge it for one hour before putting it away
the first time.
At mophie, we are dedicated to making the
best quality products we can. To back this up,
your juice pack is warranted for 1 full year from
the date of purchase. Be sure to register your
product at mophie.com to activate it and check
for the latest product updates as they develop: https://www.mophie.com/articles.asp?id=155
Web Contact: www.mophie.com/cs
Service Hours: 9am to 6pm M-F ET
I like this too: http://www.mophie.com/mophie-Juice-Pack-Reserve-p/2035_jpu-reserve-2-red.htm