Controller shows E11 and prevents starting; battery voltage reading is low.

Safety: Disable auto-start. Use correct polarity when connecting chargers or jump leads.

• Measure voltage: Confirm the battery voltage at the terminals. If low, charge the battery with an external charger rated for the battery type.
• Inspect charger operation: Verify the JCB battery charger has an AC supply and is outputting the correct float voltage. Check fuses and wiring.
• Check for drains: With the charger off, use an ammeter in series with the battery to detect any unexpected current draw from the control panel or accessories.
• Battery condition: If the battery will not hold a charge or is older than 3–5 years, replace with a new battery of the specified capacity and type.
• Clear alarm: After restoring voltage, clear E11 and test starting performance.