Quick Answer: Power Connection and BMS Communication Are Different

When several battery packs operate in parallel, connecting them on the DC power side does not automatically connect their BMS units on the communication side.

For the DALY 4th Gen Home Energy Storage BMS architecture covered here, the practical communication path is: Each Pack → Its BMS → Automatic BMS Identification → Internal RS485 → Main/Host Communication Point → Inverter Communication.

The customer therefore needs to verify three things separately: each pack has the correct BMS, the BMS units can be identified and linked internally, and the battery system uses the interface and protocol required by the exact inverter.

Key point: Electrical parallel connection ≠ BMS communication ≠ inverter communication.

1. Each Battery Pack Still Has Its Own BMS

In a multi-pack battery bank, each battery pack is managed by its own BMS. The BMS monitors and protects that individual pack before the packs participate in the larger energy storage system.

This means the power architecture and the communication architecture should be checked separately. A common DC connection does not create a BMS communication network by itself.

2. Make Sure Every BMS Can Be Identified

Once several BMS units share one multi-pack system, the system needs a reliable way to distinguish one BMS from another.

In the supported DALY 4th Gen parallel architecture, automatic BMS address identification reduces the need for manual DIP-switch address configuration during commissioning.

Customer check: Can the system identify each BMS correctly before you continue to inverter communication?

BMS identification solves the device-identification step. It does not, by itself, confirm inverter compatibility.

3. Connect the BMS Units Through the Internal Communication Layer

For the DALY 4th Gen architecture covered by the available product materials, internal communication between parallel-pack BMS units uses RS485 in a daisy-chain arrangement.

A simplified communication path is: Pack 1 / BMS 1 → Pack 2 / BMS 2 → Pack 3 / BMS 3 → … → Pack n / BMS n.

This RS485 communication path is different from the main DC power connection between the battery packs.

Actual connector pin definitions, cable sequence, termination, and commissioning procedures should follow the applicable DALY product documentation.

4. Separate Internal BMS Communication From Inverter Communication

A CAN or RS485 interface alone does not establish inverter compatibility. The exact inverter model and required communication protocol must also match the selected BMS configuration.

Customer rule: Interface compatibility and protocol compatibility are separate checks.

5. Multi-Pack Communication Commissioning Checklist

Complete these checks before treating the parallel battery bank as an integrated BMS communication system.

6. What Does DALY 4th Gen Support for This Architecture?

For supported monitoring configurations, individual pack information can include pack number, operating state, voltage, current, SOC, charge MOS status, and discharge MOS status.

This article stops at communication topology: who is identified, how the BMS units are linked, and how the battery system reaches the inverter interface.

Next integration question: If you need to determine what multi-pack battery data the inverter receives—such as SOC, current, alarms, or other system-level information—verify the system-data behavior separately for the applicable BMS configuration and inverter protocol.

FAQ

Does each parallel battery pack need its own BMS?

In the multi-pack architecture discussed here, yes: each battery pack is managed by its own BMS, while the communication architecture links the BMS units at system level.

Does DALY 4th Gen use RS485 between parallel packs?

In the DALY 4th Gen architecture covered here, internal parallel-pack BMS communication uses RS485. Do not generalize this to every DALY product or every energy storage architecture.

If both the BMS and inverter have CAN, are they compatible?

Not automatically. The physical interface, exact inverter model, communication protocol, and selected BMS configuration must be checked together.

Request a Parallel BMS Communication Review

For a multi-pack energy storage project, send DALY your battery chemistry, S count, capacity per pack, number of parallel packs, BMS current requirement, exact inverter brand/model, required CAN/RS485 interface, communication protocol, monitoring requirement, and expected quantity.

This allows the technical team to verify the communication architecture before sample testing or commissioning.