I've wondered about this for a while so here goes... Is there a way to prevent your LA battery bank from discharging more than 50% ? I don't want to be away for the weekend just to come back and find my battery bank ran down to 0% overnight due to some unforeseen event.

Thanks,

Ingo

Yes.

With a BMV and some clever software OR hardware. 

1 hour ago, The Terrible Triplett said:

Yes.

With a BMV and some clever software OR hardware.

Hi "TT",

More details please! I have a BMV702 installed so I guess you are referring to the "relay" function in that unit?? I have been toying with the idea of using that relay to switch on/off a small home built HWS (geyser in SA taal). I have an evac tube heater but after a day or two of cloudy weather I have to turn on the inst. LPG water heater. Whereas the 1410AH batteries are already fully charged by midday, even on cloudy days, so I could be using the excess PV power to heat water????

Thoughts?

Spot on. You can use the BMV's relay like I did yes.

OR use software like ICC if you have a Axpert inverter. More control.

Before the days of ESS I used a BMV set to switch the relay at 60% SOC and then back at 70% to give it some hysteresis.

This was then connected to the Multiplus configured with internal assistants using the "ignore A/C" based on various conditions, one of which was the state of one of the digital inputs connected to the BMV. Worked very well. I also connected a simple toggle switch to the same input in parallel mounted on a panel so I could switch to A/C at any time manually. 

In addition I used the battery charge assistant on another input with a switch so I could then manually decide whether to charge the battery from A/C or not (Used when the generator was the A/C source - I needed to load it a bit to make it run efficient).

 

Ok, I took the plunge and changed my setup from normal 'UPS' mode to ESS. I also took the opportunity to upgrade to the latest firmware. After all came back up I set my ESS to Optimized with Battery Life using all the defaults EG. 50W set point etc (and No PV). I see my Quattro is showing Absorption instead of Float. Is this normal? Am I correct in assuming it will happily 'assist' with 50W towards the loads but at what point will it decide to charge back up to 100% again or should I just leave it. My BMV is set to a 50% Discharge Floor and a Inverter Restart at 60%

That's it, no other changes made. Can I now expect that it will carry load during a power failure up to a DOD of 50% and then drop the loads to protect the batteries?

Last question, does ESS overrule the 'DC input low shut-down' below which was set by the Installer? The catch was I could trip the unit when I heat up a cup of coffee in the micro and the dreaded hairdryer is switched on elsewhere in the house 

Ok, so maybe not last question. Could I also have just gone the non-ESS mode and just selected the SOC values in the Quattro itself? All my loads are on AC-1 Out and AC-2 Out.

4 hours ago, Ingo said:

my Quattro is showing Absorption instead of Float. Is this normal?

After a restart (which would implicitly happen after you flash firmware and run veconfigure) a new charge cycle starts. So that is normal.

4 hours ago, Ingo said:

Am I correct in assuming it will happily 'assist' with 50W towards the loads

No. The 50W is the "grid setpoint", this is the level at which it attempts to keep the grid import. Let me take a step back: ESS attempts to keep your grid import at zero. It will take as much as possible out of the batteries and PV, and fall back to the grid if the batteries are either too low or you exceed the capacity of the inverter. Except I lied about keeping it at zero... What it does is keep it at the grid setpoint. It is common to set the grid setpoint slightly above zero (50W default).

So it will assist with as much as is needed to keep the meter at 50W... until the batteries are low or the inverter capacity is exceeded.

4 hours ago, Ingo said:

My BMV is set to a 50% Discharge Floor

It doesn't use the BMV setting. In the ESS page on the GUI you set a minimum soc. That is what it uses. Additionally, batterylife may stop earlier. Batterylife will adjust the active soc limit upwards for every day that the battery doesn't get a full charge, and downwards for every day that it does get a full charge, thereby dynamically arriving at an optimal minsoc and adapting to changing seasons too.

When using ESS, it uses the adaptive cut-off that you configure into the assistant. When running off-grid it uses the values you highlighted in veconfigure. 48.2 is too high, you will get nuisance tripping. Lower it to 47.5V at least.

Also, don't use the shut-down on SOC in an ESS situation. Disable that, unless you know what you are doing. When running ESS the Color Control is in charge. Those settings run on the Multi and takes control away from the CCGX. Two cooks in the kitchen spoils the broth.

11 minutes ago, plonkster said:

After a restart (which would implicitly happen after you flash firmware and run veconfigure) a new charge cycle starts. So that is normal.

Saying that I am a bit confused is an understatement. The inverter itself have both Bulk and Absorb leds On but the remote console shows Absorb only. After a few hours the voltage has dropped to 51.x so far with no indication of charging back to 100%

12 minutes ago, plonkster said:

So it will assist with as much as is needed to keep the meter at 50W... until the batteries are low or the inverter capacity is exceeded.

So how does this work when there is no PV? It will just drain the battery up to which point?

13 minutes ago, plonkster said:

In the ESS page on the GUI you set a minimum soc

I tried setting this to 95% as a test but it doesn't save the value, it always jumps back to 100% (running V2.23).

15 minutes ago, plonkster said:

When running off-grid it uses the values you highlighted in veconfigure. 48.2 is too high

This was set by the installer when running non-ess mode just as a UPS. It works but does trip every now and then. I will adjust it lower but then back to the original question:

How do I (easily) prevent the battery from draining below 50% during an extended power failure without having to use external control to switch loads off? Should I go back to non-ess mode and enable the SOC shutdown or does ESS without PV have a better/newer way of doing things?

1 hour ago, Ingo said:

Saying that I am a bit confused is an understatement. The inverter itself have both Bulk and Absorb leds On but the remote console shows Absorb only. After a few hours the voltage has dropped to 51.x so far with no indication of charging back to 100%

Aaah yes, that does confuse people sometimes. The inverter is not charging. The #1 and #2 on the screen means it has stopped discharging because the SOC is lower than the configured minimum. The charger state is however still absorption... so once the sun rises, it will do an absorption run. Once the voltage drops low enough you should actually see it drop back into Bulk. When running ESS the Multi is in charge of charging, the MPPTs just follow what the Multi tells it. The Multi will keep track of charge mode through the night and continue where it left off tomorrow. Do not worry about this, it is perfectly normal.

1 hour ago, Ingo said:

So how does this work when there is no PV? It will just drain the battery up to which point?

Up to this point:

The active limit is maintained by BatteryLife. It is moved up by 5% every day that the battery does not get a proper charge (above 85%). It is lowered by 5% on every day that the battery becomes full. In other words it attempts to adjust to the seasons. It will never go lower than the setting above it.

If you don't want this auto-tracking, then use Optimised WITHOUT batterylife.

1 hour ago, Ingo said:

I tried setting this to 95% as a test but it doesn't save the value, it always jumps back to 100% (running V2.23).

That is weird. There is nothing in there that would cause it to do that. If it persists, send me the VRM ID by PM.

1 hour ago, Ingo said:

draining below 50% during an extended power failure

aaah! That is an important detail I was not aware of. Yes, for that, you must use the veconfigure setting. The one I told you to disable. I was wrong about that, that is what it is for. But set it lower than the ESS MinSoC to avoid confusion.

It might also help to understand how the BMV fits into all of this. The CCGX will take the SOC measured by the BMV and copy it to the Multi, so that the Multi is aware of the SOC as measured by the BMV. The Multi can then use this SOC to switch off when required.

@plonksterPM sent.

1 hour ago, Ingo said:

@plonksterPM sent.

There appears to be nothing wrong with your setup. Probably finger trouble. I replied to your message 🙂

Just for everyone's benefit. The Venus Enter key is the Space key, or something like that.

Ok, I've adjusted my setup to the following:

Set ESS mode to Keep Batteries Charged after some testing with the Battery Life Optimised. Once I have PV I will revisit this.

Set Inverter to Shutdown SOC at 50% and Restart at 60% Hopefully this will keep the batteries from dying during an extended outage. When PV is installed I will change this to be slightly lower than the Min SOC on the Venus.

Change my Inverter DC Low Shutdown voltage down from 48.2V to 46V. For reference, 48.2V is my LA battery's +-50% voltage but it doesn't allow >5kva pikes, it trips and using voltage to guage SOC is not very accurate - but it worked fine.

Seems right @plonkster ?

PS. Thanks for the guidance.