If the internal BEC is rated at 100mA and the receiver draws 130mA then theres not enough power.

100mA delivered down three wires will draw 33.333mA on each wire (if theyre the same resistance. It doesnt matter how you connect them to the receiver youll get the same.

With the spektrums your receiver will probably cut out if you dont use a seperate BEC which delivers a bit more power and has a capacitor to smooth out the voltage.

For smoothing out dips in voltage due to motor starting etc you can stick a capacitor in and that sorts it out. A seperate BEC has a seperate power supply to the capacitor which means it can deliver more power. The ones we use (thanks Geoff - http://www.technobots.co.uk/Data Sheets/1062-010.pdfhttp://www.technobots.co.uk/Data Sheets/1062-010.pdf) can deliver 1.5A.

Dave, the best way i can describe it is that voltage will relate directly to pressure in a water system. If you have three wires at the same voltage/pressure, the voltage/pressure is unaffected (ie: an equilibriam is formed).

Current is available but if not used it doesnt flow.

Its actually described a lot better in my 1903 version of the electrical educator (how sad do you want me to get?). The older text books use the terms pressure and flow for voltage and current which I found useful.

Andy