Hello,
CAUTION: I don't have sufficient knowlege to validate it, so consider this post as a proposal or testimonial, no more!
components:
- LiIon pack with 2 PROTECTED 18650accumulator: 8.5 $: http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=280970013189
- Dc-Dc step-up: 3$: http://www.ebay.com/itm/DC-DC-3V-to-5V-9V-Voltage-adjustable-step-up-Power-Transformer-Module-40-85-/251154128233
- Holder: http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=150763929115
- breadboard (1.5 $!): http://cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=270973557315
- Usb-to-5.5 mm power cable: cgi.ebay.fr/ws/eBayISAPI.dll?ViewItem&item=180970043814
for testing:
- voltmeter: 2$: http://www.ebay.com/itm/LED-Panel-Meter-Mini-Lithium-Battery-Digital-Voltmeter-DC-3-3V-17V-/330807982367
- multimeter (Ampere meter)
here is the work:
as you see, accumulator rather empty (3.6 V range from 4.0 to 3.2), current is 500 mA
I use O'Maxi, with ethernet, TTY debug, Usb (via powered hub)
I set output Voltage of Dc/Dc converter at 6V (without load)
Input current is 400 to 500 mA.
BTW input current to O'Maxi is 230 to 280 mA
OlinuxInoxMaxi runs 3 hours; it is very less than the 10 hours expected (capacity of 4000 mAh divided by 400 mA). I will continue to investigate it.
NOTE: also possible: "universal" version using up/down converter (15$): http://www.ebay.com/itm/DC-DC-Converter-Regulator-Step-up-Step-down-2-in-1-/370538642812
Regards
PO.