Preventing Unwanted Battery Drain

Learn why your ESS drains while charging your EV, how Hypervolt interacts with solar systems, and how Battery-Safe can helps prevent unwanted battery drain.

The Role of Your Energy Storage System (ESS)

To understand why unwanted battery drain occurs, it’s important to first understand how your ESS works. The ESS is designed to:

• Monitor your entire property’s energy usage.

• Charge when energy demand is low or when free/cheap energy is available (e.g. surplus solar or off-peak tariffs)

• Discharge to power your home when demand is high, avoiding expensive grid electricity

This behaviour is automatic and based on the ESS detecting an electrical load on your property.

Unwanted ESS Drain – What’s Causing It?

To your ESS, the Hypervolt is just another household load. When you plug in your EV, the ESS detects the new demand and begins discharging to meet it, regardless of whether your intention is to charge using grid energy or surplus solar. This behaviour is automatic and by design.

Another commonly asked question is: 

"Why Isn’t My EV Charging Directly from Solar when theres surplus to charge the EV Instead of the Draining the Battery?" 

Even with solar surplus, the ESS may discharge if it detects sudden demand. This can happen:

• Before solar energy production ramps up.
• If the ESS determines that stored energy is the fastest way to meet the load.

To address this problem, we’ve introduced a new charging mode: Battery-Safe.

This mode is designed for customers who want to charge their EV using surplus solar energy only, whilst preserving battery capacity for other uses.

For more information on how to unlock Battery-Safe please see: Home Battery System Setup

Preventing Unwanted Battery Drain

Option 1: Inverter Scheduling (if supported by your ESS)

Set your inverter to not discharge when EV charging is active. Some newer inverter models allow you to schedule discharge times or detect EV load through additional CT clamps.

• Pro: Smart and dynamic

• Con: Only available on certain inverter models

Option 2: Place the ESS CT Clamp downstream of the Hypervolt 

By adjusting the location of the ESS CT clamp downstream of the Hypervolt so that the Hypervolt sits outside of the ESS monitoring zone. 

• Pro: Guarantees the ESS won’t respond to EV charging

• Con: ESS no longer accounts for EV charging in your total energy profile

Standard CT Configuration 

In this setup, the ESS CT (BATT CT) is installed upstream, alongside the Hypervolt CT. This includes the Hypervolt within the ESS monitoring zone, but may lead to the battery discharging when the EV is charging, even if unintended.

Adjusted CT Configuration

Here, the ESS CT is placed downstream of the Hypervolt, placing the charger outside the ESS monitoring zone. As a result, the battery doesn’t detect the Hypervolt load and won’t discharge, helping to prevent unwanted battery drain during EV charging.