I have a problem to understand the minimum switching voltage of the relay, especially, what impact it has. I found these topics that briefly mention, but still unsure what to make of it
Can I drastically undervolt/underpower a relay?
Parameters when choosing a relay
The voltage across the relay is ideally 0, right?
So I it is perhaps the voltage drop on the relay. But what confuses me, since the resistance of the relay is very low relatively high currents would be required to produce ot.
May be I better understand with an example.
Edit3: more details about usage of the relay
I consider this relay that would be used on a custom board for testing and measurement of batteries (lithium and otherwise). It would connect/disconnect charging/discharging currents 1 µA to 25 mA. Battery voltages in range 1V-4.5V. The relay isto be controlled from Rapsberry PI 2. Since GPIO pins don't have current capability to drive the coil, the control signal would be shifted to the main analogue voltage level of 5.5 V.
EDIT2 : a rough presentation of how the relay would be used
Edit: example from the datasheet I linked. It is in contact, not coil section
If not it would be very unfortunate because it is only compact DPST relay availible.
For this case additional question:
can be a DPDT relay be used in place of DPST?
Best Answer
Relay contacts used for switching signal levels often have a minimum current and voltage specified. Below that voltage or current you may not get a reliable connection.
You may be able to force a larger current to briefly conduct a suitable "wetting current" through the contact to it, after which a smaller current will be okay until the relay opens and closes again. One method would be an RC across the contact, if the voltage is adequate.
The one you have specifies 100uV. Another type that I'm familiar with specifies "10μA 10 mV DC". I think there should be a minimum current specified as well. You can ask the manufacturer for what they recommend (expect a certain amount of prevarication).
You can use a DPDT relay in place of a DPST, just ignore the normally closed contacts. Most relays of this style are DPDT.