Deye/Sunsync failing to low voltage disconnect

[kolek]

the inverter itself will shutdown

I'm talking about a case where it has a grid connection, so it has no need to pull anything from battery. You're talking about a case where the inverter has no access to grid, like at your cabin, right?

 

[timselectric]

This is normal.
The controls need to be powered from the battery. Otherwise it wouldn't be able to operate in a grid failure situation.

 

[Daddy Tanuki]

I'm talking about a case where it has a grid connection, so it has no need to pull anything from battery. You're talking about a case where the inverter has no access to grid, like at your cabin, right?

doh! forgot abut that, but yes offgrid. wonder what would happen if I had it setup with grid input, dead batteries and the grid went down.... Does your unit have a resume setting for charging after the battery drops to xx.xx volts? is it adjustable?

 

[kolek]

@timselectric Hey buddy thanks for coming on the thread. Wow I am kinda blown away by this. So all inverters are behaving like this, more or less? They're all just kinda joking around when they say "Battery shutoff voltage" and they're gonna continue pulling 50-70 watts off the battery forever whether you like it or not, regardless of the potential for damage to the battery, and the BMS LVD is your last line of protection in place to save your ass?

 

[Daddy Tanuki]

@timselectric Hey buddy thanks for coming on the thread. Wow I am kinda blown away by this. So all inverters are behaving like this, more or less?

I would think if grid tied they would, but once again what or where is the setting for the resumption of charging?

 

[kolek]

The controls need to be powered from the battery. Otherwise it wouldn't be able to operate in a grid failure situation.

Hmm. I'm a computer engineer, someone like @SeaGal who's also an engineer might have a good opinion on this as well, but there's no hardware or software reason why the inverter controls MUST be powered exclusively from battery, they could design these things to run from either, and not overdischarging the battery is mission critical. If this is normal behavior in the inverter world, then what can I say? Pretty dumb design.

 

[Daddy Tanuki]

Hmm. I'm a computer engineer, someone like @SeaGal who's also an engineer might have a good opinion on this as well, but there's no hardware or software reason why the inverter controls MUST be powered exclusively from battery, they could design these things to run from either, and not overdischarging the battery is mission critical. If this is normal behavior in the inverter world, then what can I say? Pretty dumb design.

deleted

 

[timselectric]

So all inverters are behaving like this, more or less?

Yes, if they have a battery.

They're all just kinda joking around when they say "Battery shutoff voltage"

They do shut off the AC output, from battery.

and they're gonna continue pulling 50-70 watts off the battery forever whether you like it or not,

They will draw whatever they require to continue monitoring the situation and be ready to comply with the chosen settings.

regardless of the potential for damage to the battery, and the BMS LVD is your last line of protection in place to save your ass?

The BMS is the last line of battery protection.
But, your settings should keep your system from needing that.
You have to adjust your settings to accommodate this draw.

 

[kolek]

You have to adjust your settings to accommodate this draw.

Ok, this has been an eye-opener. Your Growatts are doing this too?

 

[timselectric]

Hmm. I'm a computer engineer, someone like @SeaGal who's also an engineer might have a good opinion on this as well, but there's no hardware or software reason why the inverter controls MUST be powered exclusively from battery, they could design these things to run from either, and not overdischarging the battery is mission critical. If this is normal behavior in the inverter world, then what can I say? Pretty dumb design.

If the inverter includes a battery option. This means that it's designed for off grid or grid failure backup. And must be powered by the battery to carry out its designed functions.
If it were powered by the grid. When the grid was lost, it would also be lost. Because it's power source is gone.

 

[timselectric]

Ok, this has been an eye-opener. Your Growatts are doing this too?

Yes, if a battery is connected.

 

[kolek]

And must be powered by the battery to carry out its designed functions.

This is an engineering question, and there's computer hardware and software logic designed specifically for "If/when do X/Y." I've written code for systems that do far more complicated things than having 2 power sources for 1 set of controls.

Beyond the scope of this thread, but it's not only technically possible, it's technically easy to have the controls capable of running by either battery or grid power, and it's pathetically bad design architecture to have it working this way.

Either way, I see that's not how this system works and will adjust my settings to work around it.

Thanks @timselectric for your help!

 

[timselectric]

This is an engineering question, and there's computer hardware and software logic designed specifically for "If/when do X/Y." I've written code for systems that do far more complicated things than having 2 power sources for 1 set of controls.

Beyond the scope of this thread, but it's not only technically possible, it's technically easy to have the controls capable of running by either battery or grid power, and it's pathetically bad design architecture to have it working this way.

Either way, I see that's not how this system works and will adjust my settings to work around it.

Thanks @timselectric for your help!

The way I handled it when I was connected to the grid. Was to set grid charging to just enough to cover the idle draw. (2a , if I remember correctly)
Which technically means that the grid is powering the inverter.

 

[kolek]

set grid charging to just enough to cover the idle draw.

That is a clever workaround. I'll look into doing the same. Thanks for that tip.

 

[kolek]

Was to set grid charging to just enough to cover the idle draw.

Set up TOU such that if anytime voltage falls below 50.2V, charge by 50W to offset this loss
Will have to see if this actually works. Deye firmware seems a little buggy.

 

[Daddy Tanuki]

magnums have a setting if voltage hits xx.xx volts then go back into bulk charging. I never bothered to set it as at most I might use a genset to charge the batteries. so it was only charging if the AGS commanded the genset to start.

 

[kolek]

TOU seems completely broken, doesn't seem to do anything no matter how I set it.
Only way I'm able to get around this issue and recharge the batteries is by switching from "load first" to "battery first."
That function actually works.

I would update the firmware but the only way Deye allows you to do that is by letting their engineers do it, and I really don't trust Deye to login to my system remotely. Everything they touch they screw up, and their support is totally useless, to the point that I think they deliberately pretend to misunderstand and fail to answer any questions so that they don't have to do any work.

If it was Sunsynk or Sol-Ark I wouldn't have a problem with letting them have access. In fact I'd actually pay money to have a support contract with SunSynk or Sol-Ark.

 

[LydMekk]

If you want to regulate more precisely the level of the battery, when the grid takes over etc. use the TimeOfUse table.

 

[kolek]

If you want to regulate more precisely the level of the battery, when the grid takes over etc. use the TimeOfUse table.

Right, TOU. That menu is doing nothing on my unit no matter how I set it. Maybe something is overriding my TOU settings somewhere but I've tried all kinds of things and nothing works. I think it's a bug in the Deye firmware.

My most recent attempt to test it was setting every time slot to charge from grid at 4000W if the voltage was less than 50.2V. (This was when my voltage was less than 50.2V.) That did nothing. Then I raised the voltage to 50.7V, that did nothing. Then I raised the voltage to 54V. That did nothing. This is regardless of whether the charging pattern is set to "load first" or "battery first."

And no I'm not forgetting to check the TOU checkbox at the top to activate it.

 

[Daddy Tanuki]

Right, TOU. That menu is doing nothing on my unit no matter how I set it. Maybe something is overriding my TOU settings somewhere but I've tried all kinds of things and nothing works. I think it's a bug in the Deye firmware.

My most recent attempt to test it was setting every time slot to charge from grid at 4000W if the voltage was less than 50.2V. (This was when my voltage was less than 50.2V.) That did nothing. Then I raised the voltage to 50.7V, that did nothing. Then I raised the voltage to 54V. That did nothing. This is regardless of whether the charging pattern is set to "load first" or "battery first."

And no I'm not forgetting to check the TOU checkbox at the top to activate it.

can you send me a pdf manual for it to look at? might find something you missed...fresh eyes never hurt.