WiremanWireman · Battery system won’t charge or discharge: troubleshooting for electricians · 2023 NEC ·
Battery system won’t charge or discharge
Settings, state of charge, temperature and communication before suspecting hardware.
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How it works
A residential battery system is a battery, a battery management system (BMS) that protects it, and an inverter that moves energy in and out. Most of what it does is decided by software: operating mode, backup reserve, time-of-use schedules and limits for temperature and state of charge. That means most “won’t charge” or “won’t discharge” complaints are settings or protective limits doing their job. Hardware faults are manufacturer-specific and usually need the manufacturer’s support and tools.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- What is it not doing?
- Won’t chargeIs it already full, or is it set to charge only from solar?
- Already near full or at its charge limitNormal: battery is at its charge limit
- Solar-only charging, little solar todayNormal: no extra solar to charge from
- Neither, it should be chargingIs the battery very cold, very hot, or in direct afternoon sun?
- Yes, extreme temperatureTemperature limit
- NoTest: Check the battery’s breakers and switches
- Breaker tripped or a switch offBattery breaker or switch off
- Communication lost or offlineBattery and inverter aren’t communicating
- All on, fault still shownBattery or inverter fault
- Won’t discharge to run the houseIs the state of charge at or below the backup reserve setting?
- Yes, at the reserveNormal: battery is at its backup reserve
- No, it has charge above the reserveWhat mode is it in?
- Backup onlySet to backup only
- Time-of-use or self-consumptionIs the battery very cold, very hot, or in direct afternoon sun?
- Yes, extreme temperatureTemperature limit
- NoTest: Check the battery’s breakers and switches
- Breaker tripped or a switch offBattery breaker or switch off
- Communication lost or offlineBattery and inverter aren’t communicating
- All on, fault still shownBattery or inverter fault
- Shows a fault or offlineTest: Check the battery’s breakers and switches
- Breaker tripped or a switch offBattery breaker or switch off
- Communication lost or offlineBattery and inverter aren’t communicating
- All on, fault still shownBattery or inverter fault
- Won’t chargeIs it already full, or is it set to charge only from solar?