Sol-Ark 15k: 0-100% Battery Settings?

[dreancestere]

I watched Will's recent 0-100% LiFePO4 battery videos and thought I'd set that up (I've got no issue with the 100% advice (I'm already doing that) -- I've got some misgivings about not keeping any spare capacity in my HomeGrid Stack'd 19.2 kWh (4 module) battery, but that's a different issue). I need help in figuring out where to make changes to implement that 0% level on my Sol-Ark 15k inverter.

There are 3 places in the settings where I think I'd have to change things to go with that 0-100% battery range. The first is the Batt Setup > Discharge tab:

Shutdown: Battery voltage or % at which the inverter will shut down to protect the battery from an over discharge situation (battery
symbol on the home screen will turn red).
Low Batt: Low battery voltage or % (battery symbol on the home screen will turn yellow). Stopping point for TOU.
Restart: Battery voltage or % at which AC output will resume after previously reaching “shutdown”.

I assume I need to change the Shutdown field to 0% from my existing 10%. But, when the manual says "...the inverter will shut down...," does that mean the DC -> AC conversion (inversion?) from the PV/Battery will cease or that the actual, entire inverter (including the PV -> Battery function) will shut down? Assuming it's just the AC output that shuts down until the battery reaches the Restart number, what's a good number for Restart and Low Batt? I'm thinking I should just leave those at my existing 20% and 15%. (EDIT2: I think I'll go with 0/5/10% for Shutdown/Low Batt/Restart)

The next area is the Batt Setup > Charge tab:

Gen Charge: Uses the “GEN” input of the system to charge the battery bank from a generator.
...
b. Start %: Percentage S.O.C (state of charge) at which the system will AutoStart a generator to charge the battery....

Grid Charge: There are two scenarios in which this option is used:
a. Grid connected to “Grid” input: The inverter will limit the charge rate to the set value in “A” and the battery will charge to
100% SOC....

I've got a generator hooked to my GEN input. I think my existing settings mean that if the battery SOC falls between 15% and 20%, the battery will charge from the grid, and if the battery SOC falls below 15%, it'll fire up the generator and charge the battery from there. That should only happen if the grid is down long enough to drain the battery to those levels and then comes back on line.

EDIT1: After posting this, I realized I'll HAVE to change the Start%. Otherwise, I'll just end up charging the battery from Grid/Generator when the battery SOC reaches 20%/15% (which might be routinely). I'll have to think about that some more.

Originally, I just matched those 20% and 15% numbers to what I had on the Discharge tab's Restart and Low Batt numbers. But, I'm not sure what/if I should change them with a new 0% Shutdown setting on the battery. Should I continue to match them to whatever I decide to put in those Discharge tab numbers this time around? (EDIT2: Yes, I think I'll match the settings -- 5/10% for Gen/Grid Start%)

And then there's the Limiter (Time of Use (TOU)) tab:

Batt: V or % used to specify a lower discharge limit or upper charge limit whenever “🗹 Charge” is enabled. Grid-tied systems
will not allow TOU to discharge lower than “Low Batt V/%”. Off-grid systems allow TOU discharge down to “Shutdown V/%”.
🗹 Charge: During the hours selected, it is allowed to charge batteries from an external AC source up to a programmed voltage or
%. If the external AC power source is a generator, the “Start V” or “Start %” condition must be fulfilled first. If available, the solar array
will always charge the batteries at 100% regardless of “🗹 Charge” in TOU.

I'm using TOU solely to change the inverter's energy priority from the default:

1. Solar PV Power | 2. Grid Power | 3. Batteries | 4. Generator

to the TOU priority of:

1. Solar PV Power | 2. Batteries (down to programmed discharge V or %) | 3. Grid Power | 4. Generator.

My existing settings should mean that if my battery SOC falls below 20% (the old Battery Discharge Startup and Grid Start% numbers -- which, again, should only happen if the grid goes away long enough to discharge the battery that far), when the grid is available, charge the battery. I assume I should match that percentage to whatever I put in the Battery Discharge Startup and Grid Start fields. Is that reasonable? (EDIT2: Yes, I think I'll change the TOU Batt field to match the 10% Battery Discharge Startup and Grid Start% fields)

EDIT2: I've decided to change my Batt Setup > Discharge > Shutdown/Low Batt/Startup settings to 0/5/10%. I'll also change the Batt Setup > Charge > Gen/Grid Start% settings to 5/10% and my Limiter > Batt setting to 10%. That means that routinely, my lower battery level will be 10% and will only reach 0% if the grid is down long enough for the generator to run out of propane. I suppose I could reduce the spread of those numbers from 5% between each to maybe 1% between each. But, I don't know how accurate the inverter can see those battery values. A 10% increase in available battery is pretty good, though.

EDIT3: Interesting. I can't get the inverter to save a Gen Start% less than 10% (same as what the Grid Start%, Restart and TOU Battery settings are). I wonder which will start first: Grid charging, Gen charging or both at the same time. I assume it'll be Grid charging if the grid is available (because of the TOU energy priority. Also, since I'd only ever get to that 0% battery level in a zombie apocalypse, I bumped the Shutdown setting up from 0% to 1% (just in case the battery really doesn't like 0%).

 

[Helios605]

batt shutdown is a protective setting to keep your battery from getting to your batt empty voltage. Theoretically batt empty is supposed to be the lowest critical level the battery can still hold a charge. If you were to discharge below batt empty, your battery could drop outside of the 43V operating range drastically to a point (I.e. 10-20V) and the inverter cannot charge the batteries back up because it’s not a sustained trickle charger 1-3A like external DC chargers. An external charger would be needed, and if you’re off grid, you better have a generator w 120V receptacles otherwise you’ll be hauling your batteries somewhere to get shore power and reviving dead batteries is painfully slow.

Batt empty defines the theoretical 0% SOC on a battery performance curve where is drastically drops to the horizontal axis. Batt shutdown protects you from getting that far. As batteries age, the depth of discharge changes and increased internal resistance makes it harder to hold a deep cycle charge like they were new. Your battery manufacturer provides you with a batt shutdown percentage because they base their discharge cycle life on the gradual depth change over time and set a minimum on purpose because they plan for the battery change in chemistry. Hence if they tell you 20%, that’s because while you theoretically might have been able to go lower when the batteries were new, that deep cycle depth increases within their estimated margin of error.

So let’s say they tell you 20% but you say nah, I’m gonna go down to 5% on day one of the batteries installed. A year later, you get a DC low volt fault and you notice your batteries are well below batt empty voltage. That’s because hypothetically one year later 5% is actually now 0%. 3 years later 10% is now 0% SOC. 5 years later 15% is now 0%. All depends on your discharge cycle count

The point is they give you this shutdown value to protect your batteries and keep your system from encountering faults when you’re not paying attention 24/7. Letting your battery get critically low too often to the point you have to revive a dead battery is also speeding up the battery lifecycle and their marketed discharge cycle specification becomes a moot point.

The moral of the story is listen to your battery manufacturer’s recommendations so it doesn’t hurt your warranty coverage.

 

[Nobodybusiness]

I watched Will's recent 0-100% LiFePO4 battery videos and thought I'd set that up (I've got no issue with the 100% advice (I'm already doing that) -- I've got some misgivings about not keeping any spare capacity in my HomeGrid Stack'd 19.2 kWh (4 module) battery, but that's a different issue). I need help in figuring out where to make changes to implement that 0% level on my Sol-Ark 15k inverter.

There are 3 places in the settings where I think I'd have to change things to go with that 0-100% battery range. The first is the Batt Setup > Discharge tab:

View attachment 256173



I assume I need to change the Shutdown field to 0% from my existing 10%. But, when the manual says "...the inverter will shut down...," does that mean the DC -> AC conversion (inversion?) from the PV/Battery will cease or that the actual, entire inverter (including the PV -> Battery function) will shut down? Assuming it's just the AC output that shuts down until the battery reaches the Restart number, what's a good number for Restart and Low Batt? I'm thinking I should just leave those at my existing 20% and 15%. (EDIT2: I think I'll go with 0/5/10% for Shutdown/Low Batt/Restart)

The next area is the Batt Setup > Charge tab:

View attachment 256174




I've got a generator hooked to my GEN input. I think my existing settings mean that if the battery SOC falls between 15% and 20%, the battery will charge from the grid, and if the battery SOC falls below 15%, it'll fire up the generator and charge the battery from there. That should only happen if the grid is down long enough to drain the battery to those levels and then comes back on line.

EDIT1: After posting this, I realized I'll HAVE to change the Start%. Otherwise, I'll just end up charging the battery from Grid/Generator when the battery SOC reaches 20%/15% (which might be routinely). I'll have to think about that some more.

Originally, I just matched those 20% and 15% numbers to what I had on the Discharge tab's Restart and Low Batt numbers. But, I'm not sure what/if I should change them with a new 0% Shutdown setting on the battery. Should I continue to match them to whatever I decide to put in those Discharge tab numbers this time around? (EDIT2: Yes, I think I'll match the settings -- 5/10% for Gen/Grid Start%)

And then there's the Limiter (Time of Use (TOU)) tab:

View attachment 256176



I'm using TOU solely to change the inverter's energy priority from the default:

1. Solar PV Power | 2. Grid Power | 3. Batteries | 4. Generator

to the TOU priority of:

1. Solar PV Power | 2. Batteries (down to programmed discharge V or %) | 3. Grid Power | 4. Generator.

My existing settings should mean that if my battery SOC falls below 20% (the old Battery Discharge Startup and Grid Start% numbers -- which, again, should only happen if the grid goes away long enough to discharge the battery that far), when the grid is available, charge the battery. I assume I should match that percentage to whatever I put in the Battery Discharge Startup and Grid Start fields. Is that reasonable? (EDIT2: Yes, I think I'll change the TOU Batt field to match the 10% Battery Discharge Startup and Grid Start% fields)

EDIT2: I've decided to change my Batt Setup > Discharge > Shutdown/Low Batt/Startup settings to 0/5/10%. I'll also change the Batt Setup > Charge > Gen/Grid Start% settings to 5/10% and my Limiter > Batt setting to 10%. That means that routinely, my lower battery level will be 10% and will only reach 0% if the grid is down long enough for the generator to run out of propane. I suppose I could reduce the spread of those numbers from 5% between each to maybe 1% between each. But, I don't know how accurate the inverter can see those battery values. A 10% increase in available battery is pretty good, though.

EDIT3: Interesting. I can't get the inverter to save a Gen Start% less than 10% (same as what the Grid Start%, Restart and TOU Battery settings are). I wonder which will start first: Grid charging, Gen charging or both at the same time. I assume it'll be Grid charging if the grid is available (because of the TOU energy priority. Also, since I'd only ever get to that 0% battery level in a zombie apocalypse, I bumped the Shutdown setting up from 0% to 1% (just in case the battery really doesn't like 0%).

So many things to unpack here.

I’ll take a picture of my settings when I get time and post in here.

Not near the inverter right now and MySOLARK looks different.

 

[DougfromdaUP]

Are you really only charging to 53.2 volts?

That’s way too low. You’ll never get any equalization.

 

[Nobodybusiness]

Are you really only charging to 53.2 volts?

That’s way too low. You’ll never get any equalization.

Lots of things that need addressing.

Figured it’s just easier to post settings then try to type a book with reasonings.

 

[dreancestere]

Are you really only charging to 53.2 volts?

That’s way too low. You’ll never get any equalization.

That's what I thought, too. I wrote the Homegrid Stack'd people and specifically asked them. They referred me to their setup guide:

Stack’d Series Battery Setup Guide for Sol-Ark inverter 8k/12k/15k

This guide will help you ensure the recommended settings for your HomeGrid battery system are set on your Sol-Ark inverter. Note. Please contact HomeGrid Customer Support at 725-373-5350 if you have any questions or need further assistance. ...

lithionbattery.freshdesk.com

Which says:

3. Next, select the ‘Charge’ tab found in ‘Batt Setup’. (See Figure 3)
a. Verify ‘Float V, Absorption V, Equalization V’ are set to ‘53.2V’.
b. If operating in ‘Open Loop’ set these parameters to ‘53.2V’.
c. Press ‘OK’ to confirm changes.

Note: If operating in ‘Closed Loop’, these settings should autofill. If loss of communication occurs between the designated ‘Master’ BMS and the designated ‘Master’ inverter, the system will default to the last known settings in ‘Closed Loop’.

I'm in closed loop communication via Canbus. So, according to that, those 53.2V values are all being autofilled (and are supposedly correct). But, even then, when I look at the battery voltages in the Sol-ark monitoring software and the Homegrid monitoring software, the top voltage (at 100% SOC) don't even reach that. They top out at about 52.6V.

Note: I don't know if it makes a difference, but I'm pretty sure these Stack'd batteries are 15 cell.

EDIT: I'd even seen @Will Prowse 's video where he talks about charging voltages:

For 48V systems, he says Absorption should be 58V and Float should be 54.4V (and even the Sol-ark manual says Equalization shouldn't be done on LiFePO4 batteries). So, yep. I think those 53.2V settings are way too low. But, the manufacturer seems to disagree.

 

[Oldphile]

53.2V is correct for 15 cells. I have 16 cell batteries that sit at 56.7V.

 

[dreancestere]

53.2V is correct for 15 cells. I have 16 cell batteries that sit at 56.7V.

Thanks for the confirmation. I was just searching the internet for charging values and what I found was a recommended absorption voltage per cell of 3.55V to 3.65V for LiFePO4. For 15 cells, that works out to 53.25V to 54.75. So, that's another confirmation of what the Homegrid people said.

But, I'm wondering about the float voltage. From what I can find, that should be from 3.2V to 3.3V per cell. Or, for 15 cells, 48V to 49.5V. Odd that Homegrid is recommending that same 53.2V as it recommends for the absorption voltage.

 

[DougfromdaUP]

I missed the 15 cell configuration of your batteries. Sorry.

One other thing I've noticed is that my SolArk 12k has difficulty tracking SOC accurately. I hope that your running in closed loop fixes that, and that it gets SOC from your batteries. I have been running in open loop for over two years, and setting all my parameters by voltage has worked perfectly.

 

[2TrevorJ]

I'm in closed loop communication via Canbus. So, according to that, those 53.2V values are all being autofilled (and are supposedly correct). But, even then, when I look at the battery voltages in the Sol-ark monitoring software and the Homegrid monitoring software, the top voltage (at 100% SOC) don't even reach that. They top out at about 52.6V.

Roughly the same deal here while charging from solar in closed loop (52.7V). If you grid charge you will see the full 53.1-53.2V.

That's actually improved over previous firmware which maxed at 52.1-52.2V in closed loop. I'm not saying it was just me but I gave them some feedback on that when I first commissioned my setup.

I have my setup configured to:
Shutdown - 0%
LowBatt - 4%
Restart - 5%
Batt Empty - 43.0V (Battery Array shutdown is supposedly 40.5V according to the manual)
TOU - 5% (45.9-46.5V or so)

Of course, the first four parameters will never get used unless the grid is down as it'll always stop using the battery at 5% (TOU).

Lowest I've been is 2% (44.9V) using TOU. The BMS triggered "Request Forced Charge" via CANBUS and the inverter obliged at 11.3 kW since the grid was up. Probably had a cell or two start running for the bottom. I've seen it trigger at 3-4% also (hence the 5% floor now which has shown to be perfectly OK). Not a fan of uncommanded max effort charging.

For anyone reading...battery away SOC calculation/balancing has shown to be incredibly accurate/consistent with the Homegrid system. I swear there's some fuzzy logic going on as accuracy/management improves as you exercise the array. Stack-to-stack SOC consistency was relatively poor after commissioning and adding 4 additional battery "slabs" a year later but in both cases improved after a few weeks to where my two 38.4 kWh stacks were/are in absolute lock-step. There is no reason not to lean on this BMS to do it's job and manage the battery array appropriately all the way down to single digit SOCs (providing it doesn't just spend it's life at 100% SOC waiting for a grid failure).