I have a 9V circuit to operate latching relays. Because there are instances where two independent DC power supplies meet briefly, I decided to implement schottky diodes in the circuit to prevent them from affecting one another. Initially, I used IN4004 blocking diodes (https://docs-apac.rs-online.com/webdocs/14f5/0900766b814f5b51.pdf), but took them out because I realised they could only carry 1A of current. I subsituted them with SBYV27-200-E3 switching diodes (https://docs-apac.rs-online.com/webdocs/14ae/0900766b814ae442.pdf). I understand that switching diodes are used in instances where there are rapid and frequent switches in the power supply in both directions i.e. AC, however I have used them since they were already available and could carry up to 2A of current (vs 1A of IN4004). When I used my relay to disconnect a part of the circuit (9v measured before disconnection), I found it unusual when I measured around 2V in potential difference (with reference to GND) upstream to the diode at the disconnected part of my circuit. I was puzzled by why there was 2V when that part should have been disconnected by the relay, and any reverse current blocked by the diode. I then took those switching diodes out and switched back to the IN4004 blocking diode. With these, I measured 0V when the relay perform the same disconnection, showing that the circuit was effectively cut off by the relay and no reverse current was allowed through the blocking diode.
Thus, my question is why are my IN4004 diodes able to effectively block all current, while my SBYV27 diodes seem to allow some reverse current through? I want to clarify it this is indeed the case and whether a switching diode is similar (or not) to a blocking diode in blocking reverse current.
I added a schematic. This schematic only has one DC source, but I tested the voltage measurement on this as well. Circuit maker does not have the exact relay model I am using so I combined two of them here. When one the coil is activated, one circuit closes and the other opens, and vice versa when the reset coil is activated. My circuit might appear unusual but I've designed it to work such that the coils are operated by the very same current that runs through the switching circuit it controls.