Why is my battery half full but I am still buying power?

Does battery charge tell me how much power is available?

A percentage is an energy gauge. Capacity, measured in kilowatt-hours or kWh, tells you how much energy the battery holds. Power, measured in kilowatts or kW, tells you how quickly it can deliver that energy. A large amount stored does not remove the inverter’s output limit.

Suppose the home needs 7 kW while solar is producing nothing and the battery can supply 5 kW. The remaining 2 kW comes from the grid, even if the battery is half full. If those conditions continue for half an hour, the grid supplies 1 kWh. These are assumed figures, but the distinction explains why adding storage capacity may leave the same import spikes.

Look for the installed system’s continuous discharge rating and the output the installer has configured. Backup output and starting large appliances can have separate limits. Ask about both if you are investigating an outage as well as normal grid-connected operation.

Is the battery keeping energy in reserve?

Check the reserve setting and its purpose. Energy held for an outage may be unavailable for everyday use. The usable capacity already stated by the manufacturer can also exclude an internal protection buffer, so ask how the app’s percentage maps to the energy available to your home.

As at 13 October 2026, our VPP compatibility table (opens in a new tab) shows a 20% minimum charge for the listed battery families. The exact installed system still matters. A household reserve, the VPP minimum and a manufacturer’s protection limit should be explained together before you change anything.

Could a schedule or VPP event be holding the charge?

Check the operating mode, charging schedule and any event indicator at the same time as the import. A battery can be configured for solar self-consumption, shifting electricity between tariff periods or backup. The mode determines what it tries to do. Changing it can also affect the warranty conditions for the intended use.

During an ActewAGL VPP event, we can instruct a battery to charge, discharge or hold charge. Holding energy can therefore coincide with household imports. If you participate in our VPP, ask us whether an event was active at the recorded time and what happened before and after it.

Across the region, check the scheduler’s clock when daylight saving starts or ends. If a plan period is defined in AEST, an appliance following the local daylight-saving clock needs the appropriate conversion. Use the timetable and clock convention in your actual plan rather than borrowing a neighbour’s schedule.

Could the app be showing a different measurement?

Check whether the app shows a live power snapshot, energy over an interval or an estimate. Compare readings from the same time period. For a three-phase home, ask the installer how the battery, household loads and monitoring are connected across the phases. A screenshot alone cannot establish a wiring or equipment fault.

If the battery has reached its configured output while several large appliances are running, imports can be consistent with its design. If it is above reserve, the schedule should allow discharge and household demand is below its output limit, a repeated unexplained import is a useful event to have investigated. Treat that as a diagnostic prompt, rather than a diagnosis of the fault.

What should I send the installer or VPP operator?

Record the date and time, battery percentage, household demand, solar generation, battery charge or discharge power, grid import and operating mode. Save any alerts and note which large appliances were running. Include the battery and inverter model numbers. That gives the person helping you a specific event to explain.

Ask: “Was this import expected under my configured power limit, reserve and schedule? If so, which setting explains it? If not, what needs investigating?” Have the installer confirm any proposed change before altering backup or tariff settings. Keep the explanation so you can recognise the same pattern next time.

Related advice: How to choose a home battery · VPPs in the ACT and south-east NSW: is joining worth it?

Check what is behind the import

Our Battery Power Top-Up page (opens in a new tab) lists supported batteries and participation terms. Record one import event before seeking help. For equipment alerts, wiring or output limits, take that record to your installer. If you’re in another VPP, ask its operator whether an event explains what happened.

If you participate in our VPP, give us a call on 13 14 93 with the recorded time, battery model and screenshots. If you’re considering joining, we can talk through eligibility and participation terms.

Get help with your ActewAGL VPP (opens in a new tab)