Samlex Remote Switching

[Viron]

I would like to remotely switch my Samlex PST-3000W inverter using some sort of "latching relay" or "bistable" that draws zero current when not switching. I have a Morningstar RD-1 relay driver that I could pulse voltage to toggle the state of the relay. I'm trying to avoid throwing away about ?7.5W? of power using the middle or right circuit diagrams.

When I Google I get very few relatively appropriate hits. On Mouser I get thousands of hits that I can't sort to what I want. I'm thinking when I find the right latching relay I can trigger it with less than 50 milliamps. Does anyone know of a good latching relay? I know some Automatic Matching Units (ATU) used in ham radio use the type relay I'm looking for that use zero current except when switching.

I'll use signals from the BMS, not purchased yet, to signal the RD-1 relay driver that will shut down my Morningstar PS-MPPT-40M charge controller or Samlex PST-3000W inverter. The basic idea is a safety shutdown if the cells get excessively out of balance.

I know Chargery has mechanical relays, but they waste huge amounts of power in my opinion.

At this point I'm looking at a Chargery 8S BMS for 24VDC 8s2p battery. It has enough signal outputs to signal the RD-1.

The RD-1 and PS-MPPT-40M can commucate via MODBUS. The PST-3000W communicates via RJ-50 port to a RC-300 remote through a crossover cable. The remote is forward 1,2,3...10, and the inverter is 10,9,8...1. The channels are labelled but the protocol is unknown.

Using the RD-1 to pulse a latching relay seems straight forward and very efficient. The middle and right are straight forward, but are wasteful of power. Using com ports looks like a ripe nightmare.

Any thoughts? I'm no electronics person, but occasionally I do use a soldering iron.

 

[FilterGuy]

The RD1 is a very interesting piece of kit. I had never looked at it before but it seems like a very powerful device.

Here is the good news: I don't think you need it!

1) You can use figure one with a small SSR driven by the Chargery for only a few milliamps. (Probably a lot less than what the RD1 draws)

2) I would need to know more about the samlex, but if I read figure 3 correctly, you can just wire the Chargery output directly to terminal 3. The only reason I am not sure this will work is that I don't know if the 12V output of the chargery is sufficient when the Samlex is hooked to a 24V battery. The parenthetical note of (10-33V) makes me think it will work.
I also don't know what the current draw will be on pin 3, but I suspect it is going to be very low.

 

[Craig]

The RD1 is a very interesting piece of kit. I had never looked at it before but it seems like a very powerful device.

Here is the good news: I don't think you need it!

1) You can use figure one with a small SSR driven by the Chargery for only a few milliamps. (Probably a lot less than what the RD1 draws)

2) I would need to know more about the samlex, but if I read figure 3 correctly, you can just wire the Chargery output directly to terminal 3. The only reason I am not sure this will work is that I don't know if the 12V output of the chargery is sufficient when the Samlex is hooked to a 24V battery. The parenthetical note of (10-33V) makes me think it will work.
I also don't know what the current draw will be on pin 3, but I suspect it is going to be very low.

The Chargery should work with the samlex. It works with my samlex Evo. I imagine they are set up similar.

 

[FilterGuy]

The Chargery should work with the samlex. It works with my samlex Evo. I imagine they are set up similar.

How do you have it wired?

 

[Craig]

How do you have it wired?

I cant tell you exactly right now as Im away from that device. but it takes a 12v signal that works like a switch or a relay if there is a voltage unit is on if there is not a signal unit is off. I did read in the manual something that would work like a momentary (latching) switch as well.

 

[FilterGuy]

I cant tell you exactly right now as Im away from that device. but it takes a 12v signal that works like a switch or a relay if there is a voltage unit is on if there is not a signal unit is off. I did read in the manual something that would work like a momentary (latching) switch as well.

Cool!!! I wonder what the current is. I bet it is pretty small.

So @Viron, you can probably just wire the Chargery signal directly to terminal 3 of the connector block.

 

[Viron]

Very good. Its certainly free to try.

The RD-1 has a maximum self consumption of <20ma. PIN 3 on the Samlex I estimate to be 750ma based on interpolating fuse size and voltage.

I interpolated the 10v to 33v at a fusing of1A to be about 750ma at 10v. Current drawn would be maximum at the lowest voltage, fuses being size factored at 1.25X of the load. Hence my guess of 7.5W current.

The RD-1 draws <20ma in self consumption and can pass 750ma as load current per channel.

So, there is a HUGE difference in power consumption of PIN 3 versus a zero current latching relay on PINS 1 & 2.

I'm anal about power as my system is portable in my condo to pull out after a hurricane. There are practical limits as to how much stuff I can store. I've got 1600W of PV panels, PS-MPPT-40M, PS-MPPT-25M, and 3.5hrs average solar insolation during hurricane season.

The PS-MPPT-25M is actually for 12VDC to power ECOM ham radio, but could parallel to 24VDC system that powers lights, fan, refrigerator and microwave. Even paralleling both charge controllers I have losing battle, but typically power is restored in 3 to 5 days.

So to me using 750ma is stupid if I can run 20ma.

 

[Craig]

Very good. Its certainly free to try.

The RD-1 has a maximum self consumption of <20ma. PIN 3 on the Samlex I estimate to be 750ma based on interpolating fuse size and voltage.

I interpolated the 10v to 33v at a fusing of1A to be about 750ma at 10v. Current drawn would be maximum at the lowest voltage, fuses being size factored at 1.25X of the load. Hence my guess of 7.5W current.

The RD-1 draws <20ma in self consumption and can pass 750ma as load current per channel.

So, there is a HUGE difference in power consumption of PIN 3 versus a zero current latching relay on PINS 1 & 2.

I'm anal about power as my system is portable in my condo to pull out after a hurricane. There are practical limits as to how much stuff I can store. I've got 1600W of PV panels, PS-MPPT-40M, PS-MPPT-25M, and 3.5hrs average solar insolation during hurricane season.

The PS-MPPT-25M is actually for 12VDC to power ECOM ham radio, but could parallel to 24VDC system that powers lights, fan, refrigerator and microwave. Even paralleling both charge controllers I have losing battle, but typically power is restored in 3 to 5 days.

So to me using 750ma is stupid if I can run 20ma.

I honestly do not know but I would be shocked if that draws 750Ma. But It may draw more than 20ma. The small SSR I tested seemed to draw about 13Ma

 

[FilterGuy]

The RD-1 has a maximum self consumption of <20ma. PIN 3 on the Samlex I estimate to be 750ma based on interpolating fuse size and voltage.

That is probably *much* larger than actual. I would be surprised if the actual current is even as high as 100ma. My expectation is it is in 10-20 ma range....but I am just guessing. The best thing to do is set it up and measure it. If it is too high, go for a different solution.

 

[BoloMKXXVIII]

Very good. Its certainly free to try.

The RD-1 has a maximum self consumption of <20ma. PIN 3 on the Samlex I estimate to be 750ma based on interpolating fuse size and voltage.

I interpolated the 10v to 33v at a fusing of1A to be about 750ma at 10v. Current drawn would be maximum at the lowest voltage, fuses being size factored at 1.25X of the load. Hence my guess of 7.5W current.

The RD-1 draws <20ma in self consumption and can pass 750ma as load current per channel.

So, there is a HUGE difference in power consumption of PIN 3 versus a zero current latching relay on PINS 1 & 2.

I'm anal about power as my system is portable in my condo to pull out after a hurricane. There are practical limits as to how much stuff I can store. I've got 1600W of PV panels, PS-MPPT-40M, PS-MPPT-25M, and 3.5hrs average solar insolation during hurricane season.

The PS-MPPT-25M is actually for 12VDC to power ECOM ham radio, but could parallel to 24VDC system that powers lights, fan, refrigerator and microwave. Even paralleling both charge controllers I have losing battle, but typically power is restored in 3 to 5 days.

So to me using 750ma is stupid if I can run 20ma.

If unit goes into storage, turn off switch?

 

[Viron]

I just measure 4.8 milliamps from the 24V battery bank.

I think I'll just feed the charge controller through the BMS. I need to read.