Sol Ark 12K SOC estimation

[629658]

The easiest fix would allow the shunt to report SOC data to the inverter. It took a day or so to get my shunt setting correct but since then it’s been almost 100% correlated to my BMS data no matter sun or clouds.

 

[mvonw]

I would conditionally agree that the AIO inverters should be better at tracking SOC and if you have closed loop comms they do. Shunt technologies are not new so it can be done. In the meantime it’s an area that certainly needs improvement but is a very manageable problem once you understand what is going on.

Just remember you cannot trust the SOC information provided by your inverter. You need another accurate method of SOC measurement for verification and troubleshooting either BMS or a shunt.

But, isn’t closed loop communication relying on the accuracy of each battery accurately reporting it’s actual SOC? In my case with Trophy batteries, they are not even coming close to reporting their actual state of charge (e.g. reporting 100% when they are probably at 30% because of a defect in the BMS)?

 

[629658]

But, isn’t closed loop communication relying on the accuracy of each battery accurately reporting it’s actual SOC? In my case with Trophy batteries, they are not even coming close to reporting their actual state of charge (e.g. reporting 100% when they are probably at 30% because of a defect in the BMS)?

Yes in your situation I don’t think closed loop would help because you have 2 sources of SOC data (inverter and BMS) and you cannot determine which if either are correct. I actually thought the BMS data was the gold standard. Didn’t occur to me it could be inaccurate also. Just dumb luck I installed a Victron smart shunt but it does give me another data source to determine accurate SOC.

 

[mvonw]

Yes in your situation I don’t think closed loop would help because you have 2 sources of SOC data (inverter and BMS) and you cannot determine which if either are correct. I actually thought the BMS data was the gold standard. Didn’t occur to me it could be inaccurate also. Just dumb luck I installed a Victron smart shunt but it does give me another data source to determine accurate SOC.

Based on some other posting I’ve read in this site, I wonder how many people blithely accept the BMS values as valid, not really understanding there is a defect in the battery design/implementation. I had these batteries for a year, and thought they were great until I started paying closer attention to the discrepancies (and I’m still learning with to look at), seeing that batteries that had BMS reporting 100% SOC accepting 20 amps of charge current for hours. I think most of these server rack batteries use the same BMS manufacturer, so I bet this is more widespread than people might realize..

 

[629658]

I would agree. We have a way to go before this is all ready for prime time. I alway look for the voltage spike when I charge.

 

[mvonw]

did you follow sa trophy guide and couldnt connect ?

what is the name of that bms tool ?
may give a bit of insight in what actual bms is used

I finally got my Trophy batteries to work with Solar assistant. The trick is that I had to use the Trophy USB cable, not the Solar Assistant USB cable that they (Solar Assistant) sell for Trophy. I hope this can save someone else some heartache.

My issues is now that that Solar Assistant does not report the battery temperatures correctly (important to me at elevation in the cold north) and that the Trophy batteries are reporting bogus SOC values, which basically makes using SA useless.

This is what SA reports for battery temps on one of batts:
Maybe its in Kelvin... but it's not a decimal place issue..

Capacity
120.0 Ah
State of charge
96.7 %
Power
-154 W
Current
-2.9 A
Voltage
53.0 V
Temperature
-148.1 °C
Temperature MOS
-143.1 °C
Temperature ENV
-143.1 °C
Cycles
0
Charge capacity
116.1 Ah
Cell voltage - Highest
3.321 V
Cell voltage - Average
3.314 V
Cell voltage - Lowest
3.309 V
Cell temperature - Highest
-143.1 °C
Cell temperature - Average
-148.1 °C
Cell temperature - Lowest
-153.1 °C

 

[629658]

I finally got my Trophy batteries to work with Solar assistant. The trick is that I had to use the Trophy USB cable, not the Solar Assistant USB cable that they (Solar Assistant) sell for Trophy. I hope this can save someone else some heartache.

My issues is now that that Solar Assistant does not report the battery temperatures correctly (important to me at elevation in the cold north) and that the Trophy batteries are reporting bogus SOC values, which basically makes using SA useless.

This is what SA reports for battery temps on one of batts:
Maybe its in Kelvin... but it's not a decimal place issue..

Capacity
120.0 Ah
State of charge
96.7 %
Power
-154 W
Current
-2.9 A
Voltage
53.0 V
Temperature
-148.1 °C
Temperature MOS
-143.1 °C
Temperature ENV
-143.1 °C
Cycles
0
Charge capacity
116.1 Ah
Cell voltage - Highest
3.321 V
Cell voltage - Average
3.314 V
Cell voltage - Lowest
3.309 V
Cell temperature - Highest
-143.1 °C
Cell temperature - Average
-148.1 °C
Cell temperature - Lowest
-153.1 °C

My temps are off too Solar Assistant is supposedly working on the situation. I use my inverter battery temp probe to get a rough estimate.

 

[mvonw]

My temps are off too Solar Assistant is supposedly working on the situation. I use my inverter battery temp probe to get a rough estimate.

Great to know, yeah, I have several wifi temperature probes in my battery cabinet, but I'd rather know the cell temps, of course.

 

[629658]

Great to know, yeah, I have several wifi temperature probes in my battery cabinet, but I'd rather know the cell temps, of course.

100% agree

 

[mvonw]

100% I was just relaying this to Sol Ark yesterday. Stupid that a $130 shunt is more accurate but once you get the shunt settings right it’s very accurate. I’m now trying to figure out a way to get the shunt attached to the Sol Ark for SOC data. That would be almost perfect or even better get the Solar Assistant to provide info to the Sol Ark.

I took your advice and installed a Victron Shunt. It's only been in a week or so, but it's interesting to see how much different the Victron shunt is than the built-in Sol Ark 12K shunt. I'm seeing at least a 5% difference consistently, sometimes more. I'll probably need a few complete cycles to really form a firm opinion, but 5% on a 720Ah 48v bank is a significant power difference...

 

[629658]

I took your advice and installed a Victron Shunt. It's only been in a week or so, but it's interesting to see how much different the Victron shunt is than the built-in Sol Ark 12K shunt. I'm seeing at least a 5% difference consistently, sometimes more. I'll probably need a few complete cycles to really form a firm opinion, but 5% on a 720Ah 48v bank is a significant power difference...

5% shouldn’t matter as long as you are aware. Both the Victron and the Sol Ark will reset at 100% SOC. So they both start out the same with every full charge. Usually my Sol Ark is within 1-2% of my BMS. My Victron shunt is usually spot on once I got the shunt settings correct. I usually check my shunt every few days just to see how close my Sol Ark is. I just recently had my Sol Ark go off by 20-30%. Seems its intelligent algorithm decided I had over 2000 aH in my batteries. I actually have 928 aH. The other night it showed 100% SOC when in fact I was at 60% SOC. So I had to go into battery settings changed my pack size from 928 to 920 which triggers a re learn over 3 days. 2 days in and I’m back to tracking within 0-3%

 

[629658]

5% shouldn’t matter as long as you are aware. Both the Victron and the Sol Ark will reset at 100% SOC. So they both start out the same with every full charge. Usually my Sol Ark is within 1-2% of my BMS. My Victron shunt is usually spot on once I got the shunt settings correct. I usually check my shunt every few days just to see how close my Sol Ark is. I just recently had my Sol Ark go off by 20-30%. Seems its intelligent algorithm decided I had over 2000 aH in my batteries. I actually have 928 aH. The other night it showed 100% SOC when in fact I was at 60% SOC. So I had to go into battery settings changed my pack size from 928 to 920 which triggers a re learn over 3 days. 2 days in and I’m back to tracking within 0-3%

As an update I contacted Sol Ark about my SOC drift. They logged into my inverter and said that the AI had calculated my battery bank as over 2000 aH despite actually being 928 aH despite being entered correctly in the settings. He suggested lowering my 928 to 920 aH to force a relearn which I did. It was much better but still not close enough for my liking. A few days ago I reduced it to 910 aH forcing another relearn and now I’m tracking within 1-2% of my battery BMS and my Victron shunt. In my situation, I was seeing the Sol Ark SOC higher than my BMS reported. I would assume if your seeing SOC report lower than actual then I would try raising your battery pack aH in the settings wait 3 days and see if it’s better.

 

[mvonw]

As an update I contacted Sol Ark about my SOC drift. They logged into my inverter and said that the AI had calculated my battery bank as over 2000 aH despite actually being 928 aH despite being entered correctly in the settings. He suggested lowering my 928 to 920 aH to force a relearn which I did. It was much better but still not close enough for my liking. A few days ago I reduced it to 910 aH forcing another relearn and now I’m tracking within 1-2% of my battery BMS and my Victron shunt. In my situation, I was seeing the Sol Ark SOC higher than my BMS reported. I would assume if your seeing SOC report lower than actual then I would try raising your battery pack aH in the settings wait 3 days and see if it’s better.

Interesting. So, their software estimates capacity without regard to the actual known (err presumed known)? Yes, my Sol Ark reports consistently lower than my Victron shunt, and that amount grows between them as the batteries discharge. I really need to run the batteries down to zero and get a better sense of the real capacity of my bank. Based on load calculations, I think the victron is giving a better estimate of remaining capacity, but time will tell…

 

[629658]

Interesting. So, their software estimates capacity without regard to the actual known (err presumed known)? Yes, my Sol Ark reports consistently lower than my Victron shunt, and that amount grows between them as the batteries discharge. I really need to run the batteries down to zero and get a better sense of the real capacity of my bank. Based on load calculations, I think the victron is giving a better estimate of remaining capacity, but time will tell…

I have Solar Assistant attached to my Sol Ark and my battery BMS so I know what my actual SOC is. I also have a Victron shunt and it tracks almost 100% with my BMS SOC. Since I made those small adjustments to my battery bank capacity I have the Sol Ark tracking well too. Now I have all 3 sources within 1-3% of each other.

 

[mvonw]

I have Solar Assistant attached to my Sol Ark and my battery BMS so I know what my actual SOC is. I also have a Victron shunt and it tracks almost 100% with my BMS SOC. Since I made those small adjustments to my battery bank capacity I have the Sol Ark tracking well too. Now I have all 3 sources within 1-3% of each other.

I have Solar Assistant too talking to my Trophy batteries, but because my amp draw is so low, the BMS, apparently, are not able to measure such low loads. My batteries will often say 100% SOC when they are probably at 75% SOC. I was told this was ‘by design’

 

[629658]

I have Solar Assistant too talking to my Trophy batteries, but because my amp draw is so low, the BMS, apparently, are not able to measure such low loads. My batteries will often say 100% SOC when they are probably at 75% SOC. I was told this was ‘by design’

I haven’t had any issues with my Trophy batteries

 

[mvonw]

I haven’t had any issues with my Trophy batteries

Well according to Dan, my batteries are working as designed. I have a 35 kWh battery which is really only drawing 300 watt most of time so each battery often isn’t going of the 2 amp limits to register with the BMS on the SOC calculation….