The Bluekulu media Servers run on voltages between 12 and 24 volt DC and the supplied mains power adapter is 18 volt. The power consumption is very low but I was always assuming that it was around 5 watt as indicated by the supplier of the motherboards. We have had a number of units running in cars on direct DC power and also on inverters. We have also had the unit used with portable power supplies from Maplin (http://buy.maplin.co.uk/Free_UK_Delivery/Laptop_Rechargeable_Battery_Pac...) but they are a bit big at A4 size. and expensive.
A client recently asked whether they units could be used with reps in stores and what would be the smallest battery size that would give 4 hours of use. This required me to do some detailed checking here with some multimeters and I have the exact power supply requirements here.
- 9 volt, 0.35 amp
- 12 volt, 0.25 amps
- 13.5 volt, 0.2 amps
- 15 volt, 0.2 amp
- 18 volt, 0.18 amp
So it looks like the units are drawing 3 watts while running and slightly more when starting (20% higher)
The implication of this is that a 12 volt battery like this one http://www.maplin.co.uk/Module.aspx?ModuleNo=27088 at 1.2 Ah will run the unit for over 4 hours.
Wifi raises the power requirements raising the current to .35 amp at 12 volt.
3G Modem raises the power requirements to a max of 0.37 amp at 12 volt when running and with the network in use.
We have been looking at solar powered units for a while now for outdoor information kiosks in forests, beaches, etc. and now that the power requirements are known we can go ahead with the design.