I know I saw a thread that had this topic discussed, but I just cannot find it again with the search… Also, my scenario is slightly different.
I recently bought an E-Switch for my Bestech BMS similar to this:
https://www.amazon.com/gp/product/B017KP67FY/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
I have the wires from the BMS hooked up to the E-Switch, but where would I get power to have the blue LED turn on? I know that some people get the power from their receiver for their remote, but I have some r/c lights that are already plugged into the receiver and is taking up the pins on my receiver. Would it be possible to splice the r/c light wire that’s coming out of the receiver and take power from that wire to power the blue LED on the E-switch? Or would that just blow up my entire Eboard? 
Ask me some questions if I wasn’t thorough enough!