Well as it's a quadcopter, I'll be plugging 4 ESCs into the Hobbyking Multi-rotor Control Board, so is it the case that I'm going to have to remove the red wire from the servo leads on all but one of the ESCs, in order to not supply more power than the control board needs? I'd rather find out before I do anything, because I don't want to end up either frying my board with too much power from the ESCs or cutting the power leads and not having enough power for either the control board or the receiver.
My control board takes voltages between 3.3V and 5.5V so that shouldn't be a problem if the BECs are 5V, should it? And I would have thought that 0.5A would be plenty of current for these small devices.
You cannot get too much power to your control board unless the providing ESC (or BEC) delivers too high voltage (in which case they're faulty or incorrectly configured). Also, it is considered a bad thing to parallel several BECs (built in or dedicated) to power the same unit. As it's a quad, you're not powering anything but your rx and control board from the BEC, so you'll most probably be ok with the power from one of the ESCs BECs. As the control board also handles low voltage I don't see any problem unless your rx is very sensitive.
Also, I'm not sure of the power consumption of my RX module (
this one), it doesn't say anything on the page and I'm not sure how to measure it. This is a lot more complicated than I first thought! D:
You can use an amp meter to check, just connect it in series with the ESCs positive or negative control lead. Should the current from one BEC still not be enough, there's also the option to route one ESC's BEC to your rx, and another to your control board, but that'd require cutting the power cords between the rx and the control board and then I'd rather go with a dedicated BEC.
If voltage and current issues are a bit confusing, check out
Colorex excellent article for some of the basics. If not, my apologies.
Concerning the low voltage issue, I've now reprogrammed my ESCs to NiCad mode so that they won't do anything with low voltage. I'll have my LiPo alarm connected during flight which flashes a light and beeps when voltage is low, that should be fine as I probably won't be flying it too far away from myself.
That should also work, of course. It's a balance between the safety of the craft, of its batteries and of your surroundings =). Once below 3v the batteries will drop like a stone so keep some headroom... If your rx/tx already supports telemetry, that'd be the optimal solution that'd let you get some more distance later on.