Can an Automatic Transfer Switch...

[Dadoftheturkeykids]

Tell me about ATS and what it can do.

I am familiar with a manual transfer switch, I have one.

What I would like is to have certain circuits join my inverter when battery state of charge is 90%. Is this possible?

 

[fmeili1]

An ATS is just a SPDT relay (in case of switching 2-phase 240V loads, it has to be a DPDT relay - one pole for each phase).

The challenge is more how to use the SOC value to generate a signal to trigger the relay. Maybe your inverter has a dry contact relay which is freely programmable to get triggered depending on the SOC (maybe Victron Multiplus II ? but I don't know) which than can trigger the ATS. Or you may have Solar Assistant which reports SOC via MQTT to a smart home system which may trigger a smart relay (e.g. a Shelly realy) to trigger the ATS. You need a way to derive the 90% SOC to generate an electrical signal to trigger the relay.

 

[BentleyJ]

An automatic transfer switch is most commonly used with auto start generators. Inverters are different in that the All-in-One units have built in transfer switches so the wiring is done differently.

Typically the "certain circuits" you mentioned are moved to a critical loads subpanel and an AIO inverter is used to power the subpanel. Utility power is then connected to the AIO inverter at the AC Input. In this configuration no ATS is needed because utility power flows through the inverter OR the inverter may be programmed to use battery and solar when available then revert to utility when the battery gets low.
The Inverter does all this automatically.

 

[Dadoftheturkeykids]

I don't want to tie to the grid in any way, I have a battery bank tied to a 12v inverter hardwired to a 6 circuit manual transfer switch 120v on all circuits that isolate themselves from the main panel.
And a battery monitor.
Nothings "smart" and don't communicate with eachother.

Good point on how to communicate the SOC to the ATS. Not sure how to do that

I think you are saying an AIO is an inverter that accepts AC and DC, I don't think that would work for my purposes as I want my system to stay off grid.

Just trying to think of a way to get this 90% feature I want without rehauling my system

 

[Zwy]

You want to run dump loads once battery SOC hits 90% in an off grid system, correct?

Then you use something like this https://www.ebay.com/itm/2849250939...rZbdK9_mQSC&var=&widget_ver=artemis&media=SMS That control is used to trigger a contactor for loads heavier than 20A.

 

[AZ Solar Junkie]

I don't want to tie to the grid in any way, I have a battery bank tied to a 12v inverter hardwired to a 6 circuit manual transfer switch 120v on all circuits that isolate themselves from the main panel.
And a battery monitor.
Nothings "smart" and don't communicate with eachother.

Good point on how to communicate the SOC to the ATS. Not sure how to do that

I think you are saying an AIO is an inverter that accepts AC and DC, I don't think that would work for my purposes as I want my system to stay off grid.

Just trying to think of a way to get this 90% feature I want without rehauling my system

I'm sure you have a specific reason for it, but just seems interesting you don't want to connect keep your system completely off grid / no grid input when you are still using the grid to power other circuits. I'm just curious why that might be as it would certainly simplify the solution to your goal...

 

[Dadoftheturkeykids]

You want to run dump loads once battery SOC hits 90% in an off grid system, correct?

Then you use something like this https://www.ebay.com/itm/2849250939...rZbdK9_mQSC&var=&widget_ver=artemis&media=SMS That control is used to trigger a contactor for loads heavier than 20A.

This looks like it could work but I don't see if you can use 120v ac in/out
I see 30a @ 250v, does that mean I can use up to 60a @ 125v?

I'm sure you have a specific reason for it, but just seems interesting you don't want to connect keep your system completely off grid / no grid input when you are still using the grid to power other circuits. I'm just curious why that might be as it would certainly simplify the solution to your goal...

My reason is to learn how to make myself independent with an isolated system, but have the grid there in the learning process, I suppose weaning myself of grid dependancy a little at a time.

 

[Dadoftheturkeykids]

You want to run dump loads once battery SOC hits 90% in an off grid system, correct?

Then you use something like this https://www.ebay.com/itm/2849250939...rZbdK9_mQSC&var=&widget_ver=artemis&media=SMS That control is used to trigger a contactor for loads heavier than 20A.

Ok I re-thought this, so I would wire this on my DC side to open/close an AC switch on the transfer panel?

 

[Zwy]

Ok I re-thought this, so I would wire this on my DC side to open/close an AC switch on the transfer panel?

Yes, when battery voltage hits the level you set it at, it will open/close the relay which can be used for either AC or DC.