The answer is very simple, the 5v power adaptors used for the GPS and USB outlets use a DC to DC converter, not a step down transformer. The modern way of doing it is with switch mode techniques which enable very small devices with efficiency of 99% rather than a step down transformer which is very large and 50% efficiency. The devices are also configured so when there is no load they have very low current draw.
The BMS/Dash/ABS controllers all run internally at 5v and some may also run at 3.3v, they use similar power supply techniques with sleep modes controlled by having switched and unswitched power inputs
Thank you for the info Wayne. Will allow Google/Wikipedia to enlighten me a bit more later on. I'm a novice with the electronics. However, I really enjoy the quality of feedback by the regular contributors on this forum.
