Latching relays

[rthorntn]

Hi,

It's a solar transfer switch (Latronics SATS), I basically have to connect two terminals (2 & 6) together, this switches my solar panels to a different output, it will probably be done once a day and terminals 2 & 6 will be connected continuously for many hours at a time.

I'm thinking I want to use a latching relay, I want to drive it from an MCU I already own (Olimex ESP32-POE), reading some of the 5v latching relay specs you need at least 1A to switch them, my MCU has just over half that at 600mA @ 5V.

So am I barking up the wrong tree with latching, my thinking is terminals 2 & 6 might be connected 50% of the day in summer and so latching makes sense?

If latching makes sense whats the easiest way to get my 1A to switch it, I only need to switch very infrequently, one or two times a day, my MCU also has a LiPo battery charger.

What would you use?

Thanks.
Richard

[Psi]

Avoid the style of latching relay where you only have 2 connections and have to change the polarity to change the latch direction, they're annoying to drive. The latching relays with separate coils for each direction are easier to deal with.

Also consider if your system needs to detect what the current position of the latching relay is?
When you use latching relays you don't know what state the system is going to be starting up in after a power failure. Sometimes that's fine, sometimes not.

I've seen many small latching relays that don't need anywhere near 1A to switch.
The latch current will depend on how big the contacts are, which will depend on their rated current and the overall relay size.
I'm not sure if your latching relay is switching high current solar panel power feeds or just some logic signals. You can get tiny logic signal latching relays which draw maybe 100mA to latch.

If you need large latching relays that draw 1A you could have a small supercap in the circuit to buffer the current pulse.