Most Helpful Member
No, you can always leave out anything you later decide is redundant; it's a lot easier than adding something in later on.Did I go overboard with protection diodes and filter caps?
I'd have stayed with the single transistor cut-out; having two transistors is only needed for bidirectional control and you never want any current from battery to D+. Two transistors will double the power loss and heat to dissipate.
The mechanical regs do not have any other way of cutting the connection than by reverse current, it's a weakness not a requirement.
The cutout worked as a "latching relay", turning on when D+ reached a certain voltage and connecting it to the battery. Based on voltage alone, that would then have stayed connected until the battery went flat, so the cut-out part is a second current-operated coil around the cut-in relay that counters the field from the voltage coil when current flows from battery to D+, allowing the relay armature to release.
You could also keep the B+ sense circuit at the battery side of the power switch; as you have the 0.1uF cap on the divider, the resistors could be eg. ten times larger and still get a good reading, avoiding any voltage loss in the power switch.