Please help! My system has been runnning flawlessly for almost a month, then today I saw this strange event:

 

Around 13:30 the SOC drops instantaneously from 50% to 0%, goes into an apparent grid charge, and then sticks at 100% until the last rays of the sun faded after 6pm, and now run the household from battery as is normally the case.

Querying the BMS data shows equalliy weird trends ... all fine until 13:30

And then ...

 

Should I be concerned? How do I fix this?

 

Edited January 18, 20223 yr by Scubadude

OK I should be concerned. So the batteries (battery?) ran perfectly until 1:15am then had an apparent low SOC shutdown. This morning I have one flashing red and flashing green LED on the slave battery, nothing on the master. And still no BMS data. One for my solar guy then ...

This really worries me. The inverter and batteries are, in addition to their primary functions, also computers. We all worry about battery cycles, but how will those computers stand up to 10/15/20 years of use?

@David Tinker, you seem to have had a similar issue but unfortuntely I cant see what the solution was due to culling of posts. Could you please post your solution here so I can see if it does the trick for me?

After a day of silence from my solar guy ("I will get back to you") I was worried that limping along might be damaging the batteries. When I got home around 9pm there the was a normal 700W battery draw, but still no BMS data.  I isolated the two batteries, and the top one measured something like 22V (! I should have taken a picture) and the bottom one around 56V. 

After changing the battery size and current limits on the inverter I connected the bottom battery only, and it showed 84% SOC, normal BMS data and a row of bright green LEDs showing all is well.

Then I connected only the upper battery. Voltage ran up and down between 44 and 58.6V, while the inverter display alternated betwene 0% and 100% SOC.  So I reconnected the good battery for the night.  Is there anything else I can check before speaking to the distributor directly? 

OK, solarguy coming tomorrow morning to drop the batteries off at the distributor for a firmware update. Great that it can (hopefully) be sorted out quickly, but I really really hope this doesn't become a regular thing.

Both batteries collected on Friday and returned on Saturday.  This was for a firmware update as there was a batch of Shoto's that needed that.  The failed unit had been opened, so looks like some hardware was also changed - BMS card maybe? Anyhow, despite he broken seal and scratched paint on that battery, both are working fine for the first time with SOC LED's doing what they are supposed to (previously only had it in the slave). Just hoping that they permanently solved the problem. 

As reported here by @Justice MM and @TheoVogel my experience with multiple Shoto's is not unique.  I wrote to the Shoto SA GM Clark Zhong for some clarification on whether or not there was a bad batch, with a suggetsion of a formal recall if it is the case.

 

Edited January 24, 20223 yr by Scubadude