890
edits
Difference between revisions of "Mesh/Power"
Jump to navigation
Jump to search
→Battery
m (→Battery) |
|||
| (4 intermediate revisions by the same user not shown) | |||
| Line 5: | Line 5: | ||
== Low power nodes == | == Low power nodes == | ||
The [[hardware experiments]] page lists some nodes that can be used with low power. | The [[Mesh/Hardware experiments|hardware experiments]] page lists some nodes that can be used with low power. | ||
We can probably assume power usage of about 1 watt for most of the lower power stuff but probably not a lot less. | We can probably assume power usage of about 1 watt for most of the lower power stuff but probably not a lot less. | ||
| Line 19: | Line 19: | ||
Some USB battery packs don't allow charging and discharging at the same time. We ordered a selection of the cheaper units and tested them. Here are the results: | Some USB battery packs don't allow charging and discharging at the same time. We ordered a selection of the cheaper units and tested them. Here are the results: | ||
* [http://www.ebay.com/itm/321850110492 2600 mAh CoolGo pack] - $6.79 - Works! | * [http://www.ebay.com/itm/321850110492 2600 mAh CoolGo pack] - $6.79 - Works and verified at 2600 mAh! | ||
* [http://www.ebay.com/itm/301573240761 2600 mAh No-name "extruded aluminum square" with button] - $6 - Works | * [http://www.ebay.com/itm/301573240761 2600 mAh No-name "extruded aluminum square" with button] - $6 - Works but only ~1300 mAh capacity :( | ||
* [http://www.ebay.com/itm/181725452512 2600 mAh PowerBank "extruded plastic square" without button] - $3.75 - Works | * [http://www.ebay.com/itm/181725452512 2600 mAh PowerBank "extruded plastic square" without button] - $3.75 - Works but max charge rate 500 mA :( | ||
* [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. | ||
Most of these are rated to charge and discharge at 1 A, except the cheaper "PowerBank" which is rated at 1 A discharge but only 500 mA for charging which would limit charging to 2.5 W. | |||
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 = | ||