[mpg200]

That voltage regulator is basically a standalone BEC, pretty beefy as well, 5A is more than enough current. But it really isn’t what you need. Think of the power cap as emergency bucket of water waiting for when the reservoir needs it. Errr, ok here we go
Ignore the main motor as it will complicate the description
Imagine the car receiver electronics as a system that uses water. Think of it as a small tank of water, now the receiver itself only needs a bit of water to work, that can be represented as a small tap on the bottom of the tank. The servo however need loads of water think of this as a massive tap. The speedo BEC pumps water into the tank at a fixed rate until its full then just tries to keep it full. If the servo is not doing much (ie mainly going straight) then the only drain on tank is the small receiver tap, no problem BEC can keep up.
If there is then a sudden demand from servo (massive tap opens) then the BEC cannot keep tank full and it will start to empty. If the tank empties completely then the receiver tap runs dry and receiver glitches. The Cap (bucket of water) is dumped into the tank during a huge demand to help stop the tank running dry.


Does that help?

Basically you try it as is and if its a problem get a power cap (bucket of water)