Understanding Battery State of Charge
What your battery percentage means and how to use your system’s reserve level.
State of charge (SOC) is an estimate of the energy remaining in the battery. Read it alongside power use, charging availability, alarms and the time of day. The percentage alone does not show how long the property can keep running.
Use the reserve set for your system
Your battery type, inverter mode, backup requirements and generator arrangements determine the appropriate reserve. Use the settings in your MyEnergy handover. A percentage suitable for one lithium installation may not be suitable for an AGM or gel bank.
Grid-connected systems may deliberately retain energy for a blackout. Off-grid systems need enough energy until the next useful charging period. Ask MyEnergy to confirm your reserve and generator thresholds if they are not documented.
Understand percentage and power
Charge percentage describes stored energy. Power use, shown in watts or kilowatts, describes how quickly equipment is using it. A high-demand appliance can sharply shorten the available runtime even when the battery percentage initially looks healthy.
Watch the trend over time and compare similar weather, seasons and appliance use. A single reading gives less information than the overnight change and the charging history.
When the battery is approaching its reserve
- Reduce or defer non-essential high-demand appliances through their normal controls.
- Check current solar production and any available grid or generator charging on the system display.
- Check the monitoring timestamp and record any alarm.
- Follow your site’s generator and essential-load instructions. Do not lower the reserve or bypass protection to keep equipment running.
Why the percentage can change unexpectedly
Battery monitoring estimates may be corrected as the system obtains more information. Charging limits, temperature, ageing, changed loads and a module becoming unavailable can also affect what you see. Voltage alone is not a reliable replacement for a configured battery monitor.
Ask MyEnergy to investigate repeated large jumps, early shutdowns, persistent alarms, missing modules or a major unexplained change in runtime. Do not force a full charge or change synchronisation settings yourself.
Send a support request with your battery model, the before-and-after readings, time, current loads, charging sources and screenshots. Related help: batteries not charging, batteries discharging quickly, and battery system guides.