External Power Switch Wiring

"break the power switch circuit"? I'm unclear of what you mean by this...

FWIW, there are monitoring systems that have solid contact relays you can arbitrarily program... I use a relay to start/stop my DC genny when the batteries get very low.

31 minutes ago, InPhase said:

I don't need generator start, so I was wondering would it be possible to have those terminals be used to make or break the power switch circuit instead?

Technically yes.  This would be a mod you'd kinda want/need to do yourself--or perhaps Sean could do per your request...at your own risk.

A hardware on/off switch control does seem to be a somewhat common request...but I have not implemented it as of yet.

The reason I have NOT done so is as follows:

• Any connection to the internal processors or circuitry MUST be electrically isolated and protected from any external "oopses" as well as possible.  Otherwise, we have a very easy "kill switch" that instantly reduces the inverter to a paperweight if an unexpected event occurs.
• Technically yes, you can break the power switch signal.  Power switch simply shorts the "enable" lead to battery negative to turn the inverter on.  "Off" potential of the "enable" lead is ~5v (self-provided). 
  • BUT if this enable line somehow ends up under -0.3v or over 7v (with respect to battery negative) for even a few nanoseconds, the power chip will fail.  Heck, I've had to put a forward diode in series with the positive battery potential to the power chip just to prevent negative transients (which an anti-reverse diode does not protect against) from blowing the stupid little chip out.
  • Long lines to any external circuitry is immediately "out", as any transient will destroy the power control chip.  Not to mention unexpected ground loops through the line, etc., etc.
  • We have done this customization for one customer, but I'm afraid that it's going to be what causes inverter failure--"it won't turn on."

There are two hardware possibilities on the current inverters which are still (!) in production...

• The CPU-level parallel/sync ports ARE electrically isolated, both in signal and in internal power.  It would be possible to configure the Sync In as a "power control override" where if the port is shorted "closed", the inverter will turn on, if released, it'll turn off.  This would be via software, i.e. the screen will remain on.  (Self pull-up accomplished by internal design, but it could handle up to ~+/-12v, being an RS-232 isolation module.)
  • as the "input-output" ports are shorted together on the CPU side (i.e. single pin to processor), this allows you to literally "cascade" the on-off signal from one inverter to the next with BNC cables.
  • note that as the ports are BNC connectors, they are common to chassis potential.
• The WiFi serial port could also be potentially used as an on/off switch.  (It would not be cascadable in the same manner, however.)

34 minutes ago, NotMario said:

I use a relay to start/stop my DC genny when the batteries get very low.

Inverter genstart terminals?? 🤣

2 minutes ago, Sid Genetry Solar said:

Inverter genstart terminals?? 🤣

Yes, but not based on voltage, rather on SOC. Very specific from 5% to 15%. (Oh, and based on other more complex factors like Load demand, etc)

Sadly, i find generator control on inverters to be a highly limited feature, but useful for some basic setups.

35 minutes ago, NotMario said:

Sadly, i find generator control on inverters to be a highly limited feature, but useful for some basic setups.

Doesn't have to be automated by the inverter firmware--you can send commands to the inverter to utilize the on-board hardware too 😉

... Why, yes of course. But then i'm involving the inverter in something it need not be involved in.

I suppose it would make more sense in the much more common AC-generator use-case where the generator is connected to the inverter input.
In my case, it makes more sense for the battery monitor to control it.

Plus i was thinking in the general layman sense. Most inverters don't let you arbitrarily control the generator relay like that. 😕 But, i guess this is the GS forum - its a little different here... lol.

It's funny, i hadn't noticed the GEN commands on the webpage. Had to set the generator type to see them. I suppose i might as well add that functionality to the Victron GX module - pretty sure their inverters have a generator relay.

Is that relay bi-stable? Or just a normal solid contact...

2 hours ago, NotMario said:

"break the power switch circuit"? I'm unclear of what you mean by this...

FWIW, there are monitoring systems that have solid contact relays you can arbitrarily program... I use a relay to start/stop my DC genny when the batteries get very low.

"Break the power switch circuit" means to interrupt the wiring to the switch with an external relay to turn the inverter on and off remotely. I'm not interested in generator start from the inverter. That will be handled by a Cerbo GX.

1 hour ago, Sid Genetry Solar said:

Technically yes.  This would be a mod you'd kinda want/need to do yourself--or perhaps Sean could do per your request...at your own risk.

A hardware on/off switch control does seem to be a somewhat common request...but I have not implemented it as of yet.

The reason I have NOT done so is as follows:

• Any connection to the internal processors or circuitry MUST be electrically isolated and protected from any external "oopses" as well as possible.  Otherwise, we have a very easy "kill switch" that instantly reduces the inverter to a paperweight if an unexpected event occurs.
• Technically yes, you can break the power switch signal.  Power switch simply shorts the "enable" lead to battery negative to turn the inverter on.  "Off" potential of the "enable" lead is ~5v (self-provided). 
  • BUT if this enable line somehow ends up under -0.3v or over 7v (with respect to battery negative) for even a few nanoseconds, the power chip will fail.  Heck, I've had to put a forward diode in series with the positive battery potential to the power chip just to prevent negative transients (which an anti-reverse diode does not protect against) from blowing the stupid little chip out.
  • Long lines to any external circuitry is immediately "out", as any transient will destroy the power control chip.  Not to mention unexpected ground loops through the line, etc., etc.
  • We have done this customization for one customer, but I'm afraid that it's going to be what causes inverter failure--"it won't turn on."

 

There are two hardware possibilities on the current inverters which are still (!) in production...

• The CPU-level parallel/sync ports ARE electrically isolated, both in signal and in internal power.  It would be possible to configure the Sync In as a "power control override" where if the port is shorted "closed", the inverter will turn on, if released, it'll turn off.  This would be via software, i.e. the screen will remain on.  (Self pull-up accomplished by internal design, but it could handle up to ~+/-12v, being an RS-232 isolation module.)
  • as the "input-output" ports are shorted together on the CPU side (i.e. single pin to processor), this allows you to literally "cascade" the on-off signal from one inverter to the next with BNC cables.
  • note that as the ports are BNC connectors, they are common to chassis potential.
• The WiFi serial port could also be potentially used as an on/off switch.  (It would not be cascadable in the same manner, however.)

It's not important how the inverter gets shutdown. Any path toward that goal that doesn't simultaneously harm the inverter is good by me. I suppose I could use a DC contactor on the input side to shut it down. But the parasitic draw from four contactors is larger than the draw from four cube relays. Not terrible, just more.

1 minute ago, InPhase said:

"Break the power switch circuit" means to interrupt the wiring to the switch with an external relay to turn the inverter on and off remotely. I'm not interested in generator start from the inverter. That will be handled by a Cerbo GX.

 

Might i direct you to my Victron GX Integration thread. 😉

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There are two individual HF46 5A-rated relays with a common center pole.  Either relay can be individually controlled by the MCU.

I'm not aware of any other LF inverters (at least in the low-price range) that have anything more than a single relay.  GS has 2 relays.

So if the "sync" input was utilized as an on/off input, you would only need 1 logic level control signal (at chassis potential) with ~2mA of drive max.  Then daisy-chain the input/outputs all the way down the inverter line.

Older inverters could technically be retrofitted--as the "sync comm" module literally solders into a blank header on the Rev. C control boards.  Once I add the function support to the firmware, you'd be off to the races.