BMS Shutdown Troubleshooting
Diagnose common causes of marine lithium BMS shutdown including overload, low voltage, high voltage, heat, cold and current imbalance.
A BMS trip is a symptom. Find the reason before resetting repeatedly.
Low cell voltage
Possible causes:
- bank too small
- state of charge lower than expected
- one weak cell
- high inverter load
- inaccurate monitor
High cell voltage
Possible causes:
- charger set too high
- cell imbalance
- charger ignoring BMS
- poor integration
Over-current
Possible causes:
- inverter too large
- motor surge
- one battery in parallel disconnected
- BMS rating too low
High temperature
Possible causes:
- hot battery location
- high current
- loose terminal
- internal fault
- poor ventilation
Record the exact fault code before changing anything.
Diagnose before replacing parts
A shutdown or low-output symptom can begin in the battery, charging source, protection, cable path, monitor configuration or the load itself. Record evidence before resetting equipment so the original cause is not lost.
- Capture alarms, BMS history, state of charge, voltage at the battery and voltage at the affected equipment.
- Inspect for heat, looseness, corrosion, damage or water ingress before attempting another high-current test.
- Stop and isolate the system if there is swelling, unusual heat, odour, smoke, damaged cabling or repeated protection operation.
Work out your own numbers
Inverter DC Current CalculatorWork out the DC current a marine inverter draws from the battery bank, and check it against the BMS continuous and peak ratings before you buy.Marine Lithium Battery Bank Sizes Compared: 100Ah to 30kWhWhat each bank size runs, 100Ah to 30kWh, with worked daily loads, solar ranges and when to change system voltage.
Related pages
Marine Lithium Battery MaintenanceMaintain a boat LiFePO4 bank by checking terminals, BMS history, charging, temperature, corrosion, balance and physical installation.Marine Lithium Battery Not ChargingDiagnose a LiFePO4 house bank that will not charge from solar, alternator, shore power or generator.Alternator Overheating After a Lithium ConversionUnderstand why alternators can overheat charging LiFePO4 banks and how current limiting, temperature sensing and regulation help.Boat Solar Not Charging Lithium Batteries ProperlyDiagnose low solar output on a yacht using LiFePO4 batteries and MPPT controllers.Marine Inverter Shutdown TroubleshootingDiagnose inverter trips caused by low voltage, BMS current limits, cable voltage drop, surge loads and overheating.Storing Marine Lithium BatteriesStore a marine lithium battery safely during winter, haul-out or long periods away from the boat.