diy solar

diy solar

Victron Quattro shutdown voltage

Bluedog225

Texas
Joined
Nov 18, 2019
Messages
3,445
Location
Nab
Good evening,

I’m taking another run at figuring out a way to air condition my conex.

Here’s what I know so far:

1. Current Connected programmed my Quattro to shut down at 48 V. This threshold can be changed.

2. When voltage rises, the Quattro will attempt to restart. I believe 3 times.

3. The Midea portable air conditioner will restart when current is available. It will run according to the demand of the thermostat.

Even with an inverter air con, I want to make sure the battery bank has sufficient capacity to avoid a quick low voltage shutdown. I speculate that once the sun starts shining, voltage will go up quickly but battery state of charge will remain low. To complicate this, I can’t find how long the Quattro needs to run before it resets its restart function.

While I realize voltage is a poor indicator of state of charge of my SOK 48 volt server batteries, does anyone care to speculate as to what a good shutdown voltage would be to allow the charge controller to charge the battery bank up sufficiently to avoid a quick shut down when the air conditioner turns on?

48 volts seems too low. See random state of charge chart below. Maybe 52 volts? This would ensure that there was adequate energy stored to allow the Quattro to reset its restart cycle.

Any thoughts appreciated.


IMG_0853.jpeg
 
2. When voltage rises, the Quattro will attempt to restart. I believe 3 times.
My understanding from VEConfigure Inverter settings is that you set the voltage to restart inverting again, and it should be at least 1 volt higher than the 48V cutoff to avoid bouncing off and on. Here is a 12V screen, you’ll have to translate up to 48V

IMG_6670.jpeg
So DC input low shutdown is 48V for you, so make DC Input low restart like 51.6V
 
Thanks. I was thinking that once the sun shines on the panels, voltage would go way up without regard to the battery state of charge.
 
Thanks. I was thinking that once the sun shines on the panels, voltage would go way up without regard to the battery state of charge.
The PV voltage certainly shoots up at daybreak, but not the battery voltage, there isn’t enough power yet.
Apologies if I’m misinterpreting your intentions.
 
If you set cutoff at 48V, and restart at 51.6V, that’s roughly 10% of your battery capacity that is available to run the A/C until it shuts down again, assuming no incoming solar energy.

So if you have three SOK 48V server batteries (I don’t know how many you have), you’ve got about 15 kWh when full, so 10% of that is 1.5 kWh.
So if the A/C is using 1 kW, you’ll be able to run it for about 90 minutes before the voltage is depleted back to 48V and it will shut off.
These are all ballpark numbers.

If solar starts contributing power fast enough, the 90 minutes may be extended indefinitely.
It becomes a bucket filling/bucket emptying situation.
 
The PV voltage certainly shoots up at daybreak, but not the battery voltage, there isn’t enough power yet.
Apologies if I’m misinterpreting your intentions.
I was thinking that the voltage shown on the lynx bar would be what the inverter would sense when deciding whether to turn back on or not.

Maybe there’s some fancy communication going on where the inverter instead sees the actual battery voltage. That’s way above my knowledge level.
 
I was thinking that the voltage shown on the lynx bar would be what the inverter would sense when deciding whether to turn back on or not.
I’m pretty sure that’s the case, because the Quattro firmware is responsible for low-voltage cut-off and restart features directly,
Maybe there’s some fancy communication going on where the inverter instead sees the actual battery voltage. That’s way above my knowledge level.
If you have battery comms enabled, and a Cerbo GX with DVCC with shared voltage sense, maybe, but i doubt it,
Maybe @sunshine_eggo for this one
 
I’m pretty sure that’s the case, because the Quattro firmware is responsible for low-voltage cut-off and restart features directly,

Correct.

If you have battery comms enabled, and a Cerbo GX with DVCC with shared voltage sense, maybe, but i doubt it,
Maybe @sunshine_eggo for this one

In normal operations, if DVCC/SVS enabled, all devices use the default battery monitor voltage for their operations, otherwise, they use the voltage they measure at the terminals or the V-sense leads. I expect the inverter will use its own sense for voltage, but it should be pretty darn close to the shunt or other battery monitor as there's no current until a load is applied. Once it connects to the Cerbo, it should use the Cerbo supplied voltage.

I'd start with 52V and see how it goes.
 

diy solar

diy solar
Back
Top