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5V UPS for Raspberry Pi: Difference between revisions
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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. | 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 | 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 devices with Belkin USB cable was charging only 400mA while with Samsung USB cable I was able to achieve charging speed up to 1,000mA with same charger. | ||
== How much current do you need? == | == How much current do you need? == | ||
[[File:Charger-doctor.jpg|200px|thumb|USB Charger Doctor]] | [[File:Charger-doctor.jpg|200px|thumb|USB Charger Doctor]] | ||
It is sometimes difficult to determine how much current is your device using and how much current do you need. Of course you can use multimeter but in case you do not want to buy two USB connectors and connect multimeter between them for example using breadboard I would recommend you using ready to use solution called '''CHARGER Doctor'''. You can buy it from China on [http://www.ebay.com/ | It is sometimes difficult to determine how much current is your device using and how much current do you need. Of course you can use multimeter but in case you do not want to buy two USB connectors and connect multimeter between them for example using breadboard I would recommend you using ready to use solution called '''CHARGER Doctor'''. You can buy it from China on [http://www.ebay.com/ E-Bay] for approximately 2 USD including WorldWide shipping from many suppliers. | ||