02/06/2017 (Mon) 05:09:29
The following posts will describe each component in detail, starting with the USB powerbank.
There are several good reasons to use a USB powerbank to power the DIY laptop. One is that it integrates both the charge controller and power supply into the battery. Another is that it is cheap and easy to replace. The last is that it contains enough energy to power a laptop for several hours.
10000 mAh is sufficient for 2.5 hours of operation at 20 W, which is the maximum power drawn by a 10 W SBC, 10 W display and peripherals. 20000 mAh is sufficient for 5 hours, 40000 mAh for 10 hours and so on. If the average power use is closer to 10 W, the operation time is doubled.
Most powerbanks can provide the 5V 2A required by single board computers. A few more can provide another 5V 1A output, or even 5V 2A. This second output can be used to power a 5V 2A display.
For reference: Limefuel BLAST L150X 15000mAh 4x5V/2.1A (5V/4.2A max) w/passthrough ($35.99)
If one powerbank does not provide enough power, then multiple powerbanks can be used. One powerbank can be connected to the SBC, another to the display and so on. They can be charged simultaneously from a single USB cable by using a USB female to 2x micro USB male splitter, or USB Y cable.
Also choose a USB powerbank with passthrough charging. This feature allows recharging the powerbank while drawing power from it. This feature is needed to continue using the laptop while it is charging.
Charging USB powerbanks is very easy. USB AC adapters and USB cables are cheap and easy to find. Any USB port can be used for charging if needed. USB powerbanks are also very easy to charge off the grid by solar panel, handcrank generator or thermoelectric generator. Any source of 5V will charge a powerbank, even if only 100 mA.
The most important feature of a USB powerbank is that it can be charged separately from the laptop. This allows swapping discharged powerbanks for charged ones, which instantly recharges the DIY laptop. The discharged powerbank can then be recharged by any USB charger.
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