Hi everyone,
I suspect I might have encountered a bug in Dynamic ESS (DESS) today, potentially related to the recent firmware update.
The Issue: According to my DESS schedule, the battery was supposed to be charging during a specific timeframe today. However, when I checked the VRM, I noticed the system was deviating significantly from the Target SOC. The charging behavior was extremely erratic, rapidly cycling on and off. Additionally, I noticed on the physical Victron display that the AC loads were dropping to 0W every few seconds.
The Data (see attached screenshot): I’ve attached a screenshot showing the log from one of my BMS’s (Total Power/W). You can clearly see three phases:
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09:00 - ~12:00: A constant “sawtooth” charging pattern. (Side question: Is this sawtooth pattern normal behavior for DESS? I see this almost constantly).
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~12:00 - ~13:30: The system goes completely haywire. Massive, rapid fluctuations in wattage, essentially turning charging on/off continuously.
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13:30 onwards: The system normalizes after manual intervention.
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The Workaround: To fix it, I toggled DESS OFF and then back ON, and briefly enabled the “Keep batteries charged” function. Immediately after doing this, the system normalized and returned to the regular (sawtooth) charging pattern.
Suspected Cause (v3.70?): I have never seen this erratic behavior before. The only recent change to my system was upgrading to firmware v3.70 yesterday. Furthermore, I know at least one other person who experienced the exact same issue today, which makes it feel like more than just a coincidence.
Has anyone else noticed this behavior since updating to v3.70? Are the developers aware of a potential DESS bug causing this?
System specs:
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MultiPlus-II 48/5000 x 3 in parallel (only AC-in connected, Victron 3P75ct power meter on mains)
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4x Yixiang DIY v2 / EVEMB31 JK-BMS v15 & v19
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Cerbo GX v3.70
Any insights would be greatly appreciated!