Battery Energy Storage System (BESS) Integration

1. Overview

eMabler’s Dynamic Load Management (DLM) platform enables real-time, intelligent control of EV charging based on the available electrical capacity at a site.
When integrated with a Battery Energy Storage System (BESS) or any external power controller, the system ensures optimal use of grid capacity, maximizes charging performance, and protects the grid connection from overloads.

The integration follows a simple but robust concept:
The external system (e.g., a BESS controller) sends signals to eMabler defining how much charging current should be restricted.
eMabler then adjusts EV charging in real time based on these signals.

2. Integration Concept

2.1 External Meter Interface

eMabler uses an “external meter” input — a standardized interface for receiving control values from a BESS or other energy management system.

2.2 Inverted Control Logic

To simplify control and provide universal compatibility:

• 0 A, 0 A, 0 A = No limitation
  → EV chargers may operate at full power.

• Values above the predefined limit = Full stop
  → Charging stops automatically.

This inverted logic works with any BESS or controller, regardless of its internal logic, through our custom integration.

3. How eMabler external meter interface works

eMabler computes the limitation as:

1. Takes the maximum of the three phases:
   limit = max(I1, I2, I3)

2. Deducts it from the site’s configured maximum capacity:
   available_for_charging = site_max_current – limit

3. Distributes the available current between chargers according to priority rules and active charging sessions.

Example

Site max = 400 A
External system sends = 80 A
→ 400 – 80 = 320 A available for EV charging

If the external system sends a high value (e.g., 1000 A)…
→ available = negative → charging stops

4. How BESS + eMabler Work Together

A BESS typically operates to:

• Support grid connection limits

• Perform peak-shaving

• Mitigate overload conditions

• Provide backup or resilience during faults

When connected to eMabler DLM:

4.1 Normal Operation

• BESS measures site consumption

• If grid draw is within limits → BESS may charge itself

• Sends 0 A to eMabler → chargers are not limited

4.2 Grid Capacity Protection

If the total site load approaches the grid fuse size:

• BESS supplies power to avoid overload

• At the same time, BESS sends a non-zero current value to eMabler

• Our integration currently has three stages:

  1. normal operation (0 values)

  2. sending offline values: limit by x amps

  3. Send a big value => stop charging altogether.

  4. Result: charging stays under the grid limit

4.3 Peak Shaving

During configurable peak-price periods:

• BESS discharges to keep grid usage below the threshold

• Sends a limitation value to eMabler if needed

• eMabler throttles charging accordingly

4.4 Fault or Low SOC Scenario

If the BESS:

• Enters error state

• Loses connection

• SOC too low

• Stops supporting the site

The BESS can send a high current value (e.g., 500–1000 A), forcing eMabler to reduce charging to the minimum or stop charging entirely.

Alternatively, if BESS stops sending data, eMabler triggers offline fallback logic.

5. Safety & Fallback Logic (Vendor Neutral)

eMabler ensures safe operation even if the BESS is unavailable:

5.1 Missing Data / Offline Mode

If the BESS stops sending values:

• eMabler marks the meter as offline

• Applies offline current decrement (configured per site)

• Reduces or stops charging depending on the decrement size

This ensures grid protection even if external hardware fails.

5.2 Manual Fallback Current

A fallback limit can be configured in eMabler:

• Used when external control is unavailable

• Ensures chargers always remain within safe, predictable limits

6. Benefits of eMabler + BESS Integration

6.1 For the Site Owner

• Maximizes EV charging without exceeding grid limits

• Reduces peak demand charges

• Ensures energy storage is used optimally

• Enhances resilience against grid fluctuations

6.2 For BESS Manufacturers

• Simple, universal API based on current values

• Works with any control logic (no proprietary protocol required)

• Easy to implement and test

• Fully cloud-based, eMabler solution along with on site Battery

6.3 For EV Charger Operators

• Real-time charging adjustments

• Predictable behaviour during faults

• Easy site configuration and monitoring

8. Summary

eMabler’s DLM platform provides a straightforward, powerful way to integrate any Battery Energy Storage System into EV charging control.

Key characteristics:

• Vendor-neutral

• Phase-based current control

• Real-time limitation

• Safe fallback behaviour

• Supports peak-shaving, capacity protection, and fault handling

• No complex charger-side configuration

Enico is just one example where eMabler has already tested the BESS integration—this interface is suitable for any BESS supplier, microgrid controller, or external power management system.