Inside is a 4000mAh lithium ion battery, a charging circuit (you charge it via the USB cable
attached), and a boost converters that provides 5VDC up to 1 Amp via a USB A port. The 1 Amp
output is key for when you want to power the Pi, wifi adapters, maybe even small displays. We
hooked it up to a 2.5" NTSC display (powered from the Pi's 5V breakout lines), wireless
keyboard/mouse and a small WiFi dongle and it hummed along just fine as a mini computing
setup!
The charging circuit will draw 1A from a 5V supply (plug a microUSB connector into the pack
and then to a computer or wall adapter). You can charge and power something at the same time
but there's ~80% efficiency loss on both ends so if you charge it at 1A and draw 1A at the same
time, the battery pack will eventually go empty. However, if you're powering something thats
500mA or less, you can keep it topped up no problem. Also, when you start and stop charging
the pack, it will flicker the output, this can cause a 'power sensitive' device like the Pi or an
iPhone to reset on the power supply. If using it with a low current load, say under 100mA, the
pack may 'fall asleep' - you can use this circuit to keep the pack awake
How long it will last depends a bit on what you have connected. We ran a 'headless' pi (no
keyboard, mouse, display attached) with a mini WiFi adapter plugged into the USB port and
pinged it once a second to keep the network connection from going to sleep and it lasted 7
hours. There is a 4-step LED charge status display which you can turn on/off with the button.
However, the button is not a general on/off for the entire pack! There's no way to turn off the
pack, as long as something is plugged in, it will power it. If you need a USB power switch,
check out this item
Comes with the battery pack and a micro-B cable that you can use for charging the pack or
powering a device with a micro B port.
Revision History: A previous version of this product was 4400mAh. As of June 10, 2016 the
shipping version is 4000mAh
USB Battery Pack for Raspberry Pi - 4000mAh - 5V @ 1A (8:36)
TECHNICAL DETAILS
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Dimensions: 1.91" x 3.5" x 0.8" / 48.6mm x 89.7mm x 21.4mm
Weight: 126.7g (no cables)