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5V UPS for Raspberry Pi: Difference between revisions
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Also there is an issue with capacity. Capacity 10,000mAh means capacity of LiPol 3.7Volts battery inside power bank. After DC-DC converting you will get capacity around half - 5,000mAh for 5Volts output. If your RPi is just with all accessories is just taking out 500mA per hour this power bank will last for 10 hours maximum which is not in all scenarios (e.g. security, automation systems) enough. | Also there is an issue with capacity. Capacity 10,000mAh means capacity of LiPol 3.7Volts battery inside power bank. After DC-DC converting you will get capacity around half - 5,000mAh for 5Volts output. If your RPi is just with all accessories is just taking out 500mA per hour this power bank will last for 10 hours maximum which is not in all scenarios (e.g. security, automation systems) enough. | ||
== USB Current and USB cables == | |||
[[File:Cabling.jpg|200px|thumb|Belkin USB cable]] | |||
Firstly you should be aware of this. By specification USB 2.0 is able to provide only 500mA current but some devices (including RaspberryPi) might need more. For example RaspberryPi model B+ needs 700mA for itself + connected devices, total up to 2,000mA. Some tablets needs 2A and new Apple iPad needs if my information is correct 3A. | |||
Unfortunately not all power supplies and power banks are able to provide that much power. You can buy some cheap UPS for 500mA from Adafruit (e.g. [http://www.adafruit.com/products/1944|PowerBoost 500 Charger - Rechargeable 5V Lipo USB Boost]) but they won't be able to provide enough current for your RaspberryPi with all accesories which might use as much as 2A. Not only that some cables has high impedance and are unable to transfer enough power for your device. For example with Belkin USB cable I devices was charging only 400mA while with Samsung USB cable I was able to achieve charging speed up to 1,000mA. | |||