Firmware release v1.1.11 and v1.0.11 for the Internal BMS batteries

On July 30th 2024 Lithionics engineering has released the updated firmware version v1.1.11 and v1.1.11 for batteries with Internal BMS. This firmware is specific to smaller batteries 12V130AH in a plastic case and without CAN connector.

Change Log Details:

• removed $MSOC command and remove $RVC=2 option, hardcode NeverDie reserve to cell voltage only, approximated to 10% SOC. Having RVC at different points depending on voltages or SOC is confusing to customers. When SOC is drifting it causes RVC to trip even when voltage is well above expected reserve level. This is causing numerous support calls and upset customers. According to mfg records no one has ever set MSOC above default 10%, and no one uses higher voltage RVC=2 option. It makes most sense to remove all these confusing options and set a single NeverDie reserve based on lowest cell reaching a true 10% SOC level. It also matches with a new algorithm to reset Usable AH and SOC at the same time, hence placing voltage and SOC based reserve in lockstep at actual 10% SOC.
• changed remaining discharge time calculation to zero out at 10% SOC instead of 0% SOC, to match with NeverDie Reserve cutoff. Customers complained that the remaining discharge time was above zero when BMS triggered NeverDie Reserve, which is confusing as we want customers to start charging before they reach the reserve. Now the remaining discharge time is scaled to reach zero when SOC is 10%.
• adjusted cell voltage level for RESERVE to better match with 10% SOC measured in recent lab tests. Previous cell voltage level of 3.00VPC did not correspond to expected SOC values of 10%. As part of Usable AH algorithm implementation, it was determined that correct value is 3.14VPC. This is an Open Circuit Voltages (OCV), under load it is offset in real time by 0.01VPC per 0.1C load rate.
• added usable AH calibration function to improve SOC accuracy. Battery usable capacity slowly fades over time as battery is aging, which decreases SOC measurement accuracy. Occasionally battery capacity needs to be calibrated to improve SOC measurement accuracy. This is now done automatically when the battery is continuously discharged from 100% to 10% SOC within a 12-hr. period.
• added corrections for large >15% SOC discrepancy compared to known cell voltages during discharge. If BMS was powered off for a long-time during storage, it’s remembered SOC could be significantly higher than actual SOC of the module(s) subject to self-discharge while in storage. It is necessary to bring SOC closer to reality until a proper full charge cycle can be done to re-sync the SOC at 100%. According to lab discharge logs we selected several SOC points with discernable corresponding cell voltages, at 70%, 40%, 20%, 10%, 5%. If BMS “remembered” SOC is more than 15% above these points when cell voltages correspond to those points, the SOC is adjusted in real time to those points, to remove large discrepancy, until a proper SOC re-sync can be done by a full charge cycle.