In my project I need to power a glowplug for a second or so. This glowplug works on 1.5v, and I guess it slurps as much ampère as it can get, but it seems to work on a normal single AA battery. In my original design I thought I needed an external power source and a mosfet or relais, but with a simple resistor I can bring 3.3 or 5v back to 1.5. However, could such a glowplug draw too much current from the board to damage it? I guess a glow plug is a kind of resistor with the purpose of becoming hot, so my gut feeling says it isn't a problem, but I'd rather be safe than sorry.
If you are going to switch it through a gpio pin than you may source only a very little current. See also http://www.udoo.org/forum/index.php?threads/3295/An absolute maximum of 8 mA is suggested but not on all pins together. Normall it is about max 2-3 mA. So now you can do your own math in calculating the current for your glow plug but I suspect the current it draws will be much higher than the max of the gpio of the Neo.