My system is in a caravan with 2 x 300Ah lithium batteries in series and is 18 months old. I can’t access the BMS to get any info from them. The system use to to charge to 100% as monitored by the Victron Lynx Shunt. Now it charges to 90% then stops. Included is a screenshot of the charging SOC. Nothing is connected to the system prior to the shunt. Is the charging controlled by the Cerbo GX? There has been a firmware update installed recently.
I am going to assume everything is programmed with the correct battery profile etc.
But to evaluate whats actually going on, check if the batteries are reaching the target (absorption) voltage and being held there for the correct absorption length then dropping to float - if they do then they are fine.
If they are fine then we look at shunt settings there may be something slightly off there and it is not synchronising to full.
This will depend on what else is in the system here.
ATM we are off mains, charge is solely from solar. Battery voltage is sitting at 27.1VDC. A pic of our system is included. The Multiplus II is on the back side of this panel.
I feed all my system details and settings to ChatGPT. He came back with a lot of good information and explanation. You are right, ChatGPT pointed to the Lynx Shunt settings and made a couple of small adjustments and problem solved. Now displaying 100% SOC. Main two adjustment were Tail current: 6% (was 4%) and charge detection time to 1 minute (was 3 min).
Please don’t rely on chatgpt for a technical solution.
Getting the settings wrong could result in prematurely syncing to 100%. It needs careful monitoring and tuning to get it right.
