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Topic starter
August 29, 2026 2:41 pm
I have a 2 Flexboss21 inverters. Only one exhibits a strange issue of toggling a relay for several minutes at a periodic rate of 1 to 2 seconds. I don't see the purpose of toggling a large relay every couple seconds. It most often happens when the battery bank reported SOC is right at the selected Battery Backup Mode: Backup SOC%, just an observation. The other Flexboss21 never exhibits this issue. Also, ALL components have a finite service life. Whichever relay it is seems doomed for a premature failure at some point. To me this behavior is like a software hysteresis issue.
I have the latest firmware installed, FAAB-2727.
Has anyone else ever experienced this?
August 31, 2026 4:53 pm
I've got relay cycling on my unit when it is running in SOC mode and the battery gets full. Here is a YouTube video I made about the relay cycling I get so you can see whether it's the same as what you have. I switched to running everything voltage-controlled instead of SOC-controlled to avoid the relay cycling.
There is also a very long thread on the DIY Solar Forum if you want to read through that to see other people's experiences.
The 2727 firmware is a bit better than earlier firmwares but it definitely still has the issue.
Topic starter
September 1, 2026 2:22 pm
Thanks for your reply. I posted on DIY forum. As a retired electronics systems controls engineer, I'm highly disappointed EG4 has let it drag out this long. At Caterpillar this would have been taken care of in one or two software release cycles. EG4 needs to get on the stick!!!
September 1, 2026 3:05 pm
@shankusmc
Are you able to share your inverter's serial number with me?
Do you have any videos of this happening?
I would like to start a ticket so we can look into this issue and have someone reach out to you or you can call in if you prefer.
Topic starter
September 2, 2026 7:09 pm
I sent a reply directly to you.
