# AEMS100 battery communication checks: SOC, current sign and cluster management The easiest step to skip in the AEMS100 guide, and the one that hides the most risk, is returning to the home page to confirm EMS/BMS data: whether SOC matches the BMS backend and whether battery current direction is correct. The guide states that AEMS100 treats discharge as positive and charge as negative, and the EMS strategy depends directly on that sign. A reversed sign makes SOC appear to fall while charging and can start the genset at the wrong time. The easiest step to skip in the AEMS100 guide, and the one that hides the most risk, is returning to the home page to confirm EMS/BMS data: whether SOC matches the BMS backend and whether battery current direction is correct. The guide states that AEMS100 treats discharge as positive and charge as negative, and the EMS strategy depends directly on that sign. A reversed sign makes SOC appear to fall while charging and can start the genset at the wrong time. Three values that must be read back After configuring the battery protocol, return to the home page and confirm: (1) displayed SOC matches the BMS backend; (2) current direction is correct, with AEMS100 treating discharge as positive and charge as negative; (3) the BMS parameters match the actual protocol, especially maximum charge and discharge current. The guide explicitly notes that the EMS management strategy depends on this current, so a wrong sign is a control-logic fault, not a display bug. Selecting the cluster management mode Two paths are documented: SOC-based battery cluster management and voltage-based management for lead-acid batteries. Lithium storage normally uses SOC control combined with the charge/discharge inhibit SOC policy; lead-acid systems or sites without reliable SOC use voltage control. Genset start and stop thresholds are also set in the SOC management page, so when voltage mode is chosen, verify whether those thresholds remain effective. PCS linkage and fault isolation After setting PCS count and model, return to the home page and confirm each unit's variables are communicating. The guide says to check the RS485 line and paralleling network cable if variables are missing. If SOC and current sign are correct but dispatch still misbehaves, check DO assignments for genset IO, smart loads and fire input, plus the operating mode (self-consumption or peak shaving) against the project strategy. Record BMS protocol version and point-table revision in the commissioning report. Frequently asked questions What happens if the current sign is reversed? Charging appears as discharge, SOC trend conflicts with power flow, and the EMS may misjudge usable capacity, trigger inhibit policies early or start the genset wrongly. Verify the sign under both no-load and loaded conditions. Must each cluster be checked in one-cluster-one-management systems? Yes. Read back SOC and current sign for every BMS separately; a single reversed cluster can be masked by the averaged value across parallel clusters. Related equipment and guides [SP125HCPS](/en/product/sp125hcps) · [SP1350H54SW](/en/product/sp1350h54sw) · [STS200](/en/product/sts200-400-600) · [SP200/150HAPV](/en/product/sp200-150hapv) · [All technical guides](/en/blog/category/blog) · [Product catalogue](/en/products)。 ## What happens if the current sign is reversed? Charging appears as discharge, SOC trend conflicts with power flow, and the EMS may misjudge usable capacity, trigger inhibit policies early or start the genset wrongly. Verify the sign under both no-load and loaded conditions. ## Must each cluster be checked in one-cluster-one-management systems? Yes. Read back SOC and current sign for every BMS separately; a single reversed cluster can be masked by the averaged value across parallel clusters.