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Difference between revisions of "Mesh/Power"
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* [http://www.ebay.com/itm/252224862952 2000 mAh Motorola flat pack with integrated micro-usb cable] - $6 - No discharge while charging :( | * [http://www.ebay.com/itm/252224862952 2000 mAh Motorola flat pack with integrated micro-usb cable] - $6 - No discharge while charging :( | ||
* [http://www.ebay.com/itm/221974269792 Cylindrical unit without included 18650 battery] - $1.25 - Waiting for it to arrive. | * [http://www.ebay.com/itm/221974269792 Cylindrical unit without included 18650 battery] - $1.25 - Waiting for it to arrive. | ||
Assuming that these batteries actually have a capacity of 2600 mAh at 5v that's 13 Wh which is enough to power a 1 watt router like the NEXX WT2030F for 13 hours. That means that 2600 mAh is not enough to carry such a device through the night during winter in Oakland since the longest night is just under 14.5 hours long. It's probably a good idea to double the capacity since the capacity will drop over the lifetime of the battery. | |||
Then the question remains if a 4 watt panel is enough to charge 14.5 hours worth of power in the ~9.5 hours of "sun" on the shortest day. We need 14.5 Wh generated in 9.5 hours. So we need a bit more than 1.5 watts of charge. Let's say 2 watts given conversion losses (how big are losses?). So if we have a solar panel that's theoretically generating 4 watts in full noon sun that's definitely not going to cut it on a cloudy winter day. We need some numbers on the efficiency degradation of standard solar panels on a cloudy day. | |||
= Power usage = | = Power usage = | ||