Batrium SoC issues

RoboChicken

New member
Joined
Feb 16, 2021
Messages
18
Hello,

my Batrium WM5 has a SoC problem (or my settings). It suddenly changes the SoC to 100%. This happened multiple times now, at least 8 times or more.
This causes severe problems in my setup, I am using SolPipLog (software) which reads the SoC from the Batrium and switches my inverters from PV to Grid, on ie 50% SoC. The actual Soc is 30% or less, or much less because of the wrong SoC reading.
The pictures show the voltage and SoC reading from the BMS. It jumps (blue line) up to 100% from 60% or and other above.

What causes the WM5 to suddenly change SoC ? What parameters are involved ?
I can post all settings of the BMS if someone would kindly give me a hint where to look.

thx !
 

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OffGridInTheCity

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Dec 15, 2018
Messages
1,591
I have WM4 and my SoC is not reliable. I think its for different reasons - but I'll be interested to follow this discussion. In my case, here's a 30day example of my SoC at 6am - shows the voltage/Batrium-SoC readings. My daily cycle low battery cut-off is 49.5v and it bounces back to 49.8 or 50.0 etc. A few days there wasn't enough PV to turn on the inverter for that day so you see 50.6v on Feb 19th as an example. BUT - if you look at the trends, you can see that 49.9v/49.8v show wildy different SoCs from day to day.....

On Feb 15th it went to 0.0 SoC! Which fired a critical event and turn off my shunt readings. I just arbitrability set it to 50% to re-enable the shunt data. Its not exactly like you're situation - but you can see my interest in this overall topic as I find that Batrium SoC varies quite a bit for some reason. :)
1614017680449.png

On
 
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RoboChicken

New member
Joined
Feb 16, 2021
Messages
18
small update:
I changed 3 things
Shunt setting recalibrate in bypass - OFF
changed battery type from custom to std Li
Upped the charging voltage to 4.09V/cell and charged the battery to that voltage

Since then I havent had any problems. But there was only little sun here for the last 10 days. Will keep an eye on the SOC.
 

RoboChicken

New member
Joined
Feb 16, 2021
Messages
18
Rearranged my battery setup an reinstalled the software. It seems that the function "recalibrate in bypass" is the cause for the SOC jumps to 100%. It occured again after minutes the new system was online. I never had full cycles on the battery (installed it last winter, not enough sun here in Europe).
Maybe the software needs more time to learn the limits.
 

daromer

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Oct 8, 2016
Messages
5,645
You have to teach the system the limits. There is no smart function that learns over time.

And yes it will reset the SOC if you have set it up and its generally done when reaching bypass since bypass only should be reached when the battery bank is topped up. Therefore its important that you set that voltage tad higher than the charging voltage is.
 

RoboChicken

New member
Joined
Feb 16, 2021
Messages
18
It took a while to examine, but the Soc is now stable and accurate.
My Nissan Leaf cells are limited to 3.3V to 4.08V, so I set the bypass voltage lower.
Disabling recalibrate in bypass was the solution, @daromer gave the hint to that, thank you.
The total capacity setting for the BMS is the actual Ah with degradation. A low Soc is then also correct.
 
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