To ensure safe operation of the whole system, check the battery status at least once a year and whenever you suspect that the battery may be faulty. Old or faulty batteries pose a safety hazard to the operator.
| Wear protective eyewear and gloves. |
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Check the battery status from BMU801 LEDs.
The following LED descriptions are valid for BMU801 devices with serial number W2440101 onwards. The serial number is printed on a sticker on the back of BMU801.
For LED descriptions of older BMU801 devices (serial number W2440100 and earlier), see revision A of BMU801 User Guide (M212710EN).
BMU801 LED modes during normal operation LED color/Behavior State Actions Battery status green, all 3 LEDs steady
Device status green, steady
Battery is fully charged (SoC, state of charge = 100 %)
DC power is available. Charging is stopped or in float mode.
– Battery status green, blinking
SoC = 70–100 %
SoC = 40–70 %
SoC < 40 %Device status green, steady
Battery is charging.
DC power is available either from DC or solar input.
– Battery status green, steady, 0 to 2 LEDs blank
SoC = 100 %
SoC = 70–100 %
SoC = 40–70 %Battery status yellow, steady or blinking, 2 LEDs blank
SoC = 10–40 %
SoC < 10 %Device status green, steady
Battery is not charging.
DC power is available but the voltage level is insufficient for charging.
The voltage must be at least 15 V.
– Battery status blank
Device status green, blinking
Battery is functional but discharging.
There is no DC power and the system is running on batteries. Battery LEDs are powered off to save power.
If you want to check the battery SoC, short press the Power/Test button. The SoC is displayed in the battery LEDs. The last known battery status
Device status yellow, steady
BMU801 is overheated.
Internal temperature sensor has detected an excessive operating temperature.
Battery charging is temporarily paused until the device temperature is within the operational limits again.
– Battery status red, steady
Device status yellow, blinking
Battery is overheated.
Battery temperature sensing resistor (NTC) has detected an excessive operating temperature.
Battery charging is temporarily paused until the battery temperature is within the operational limits again.
– Battery status red, blinking
Device status yellow, blinking
Battery is faulty or disconnected, DC power is available.
The system has detected a serious battery failure.
- Check that the battery is connected and reconnect the battery if needed. The battery status LEDs display the last known battery status. The device status LED turns green.
- If the battery is faulty, disconnect the battery from BMU801. The device status LED turns steady green. The battery status LEDs of the disconnected battery display blank.
- Replace the faulty battery.
Battery status blank
Device status yellow, blinking
Battery is faulty, DC power is unavailable.
The system has detected a serious battery failure in one of the batteries (the other battery is still functioning).
- To see which one of the batteries has failed, short press the Power/Test button. The battery status LEDs of the faulty battery start blinking red.
- Disconnect the faulty battery from BMU801. The device status LED starts blinking green. The battery status LEDs of the disconnected battery display blank.
- Replace the faulty battery.
The last known battery status
Device status red, steady
Safe input current limit (10.0 A) is exceeded. If the input current exceeds 10.5 A for 30 seconds, the DC output power is temporarily disabled for 2 minutes. If the error situation continues and BMU801 cannot enable DC output power, detach the DC out connector from BMU801. If the device status LED turns into something else than steady red, it indicates that BMU801 functions correctly and there is a problem somewhere else in the system. DC output short circuit protection has been triggered. BMU801 tries to enable DC output periodically until the short circuit condition has been resolved.
DC output is re-enabled 5 times with a 1‑second interval, after which BMU801 waits for 10 seconds and tries again (this is repeated indefinitely).
Battery status blank
Device status red, steady
BMU801 malfunction. This state may appear during boot or operation. - Try pressing the Power/Test and Reset buttons. If the device status LED turns blinking red, BMU801 has malfunctioned.
- Replace BMU801.
Battery status green, steady, 0 to 2 LEDs blank
SoC = 100 % SoC = 70–100 % SoC = 40–70 %Battery status yellow, steady or blinking, 2 LEDs blank
SoC = 10–40 % SoC < 10 %Device status red, blinking
Rotary switch does not match the originally selected position during normal operation.
Charging is disabled.
- Correct the rotary switch position to match the battery capacity. BMU801 returns to normal operation.
Battery status blank
Device status red, blinking
Rotary switch is in unsupported position at startup.
DC output and charging are disabled.
- Correct the rotary switch position to match the battery capacity.
- To confirm the switch position, reboot BMU801 or reset the battery.
Battery status blank
Device status blank
BMU801 does not power up from DC input power or BMU801 does not power up from battery power. - Check that the DC input power is connected (DC in, Solar 1, or Solar 2).
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Check the polarity of the input power connection and correct if needed. 1
If you have only one battery in your system:
- Check that it is connected to the Batt 1 connector.
- Long press the Power/Test button.