Hi everyone,
I’ve been testing the Smart BatteryProtect 48V-10A and noticed a behavior difference in the alarm output depending on when the undervoltage condition occurs.
I’d like to understand if this is intentional or a bug.
Threshold = 46V and buzzer mode
Test 1 — Voltage drops below threshold while system is already running:
Start with power supply > 46V (system running normally)
-Decrease voltage below 46V
-Wait 12 seconds → P3 displayed, alarm pin goes LOW (connected to GND)
-Raise voltage back above 46V → alarm resets correctly
Test 2 — System powered on with voltage already below threshold:
Lower power supply below 46V
Power on the system → E3 displayed, alarm pin remains inactive (NOT connected to GND)
The datasheet states: “The alarm output is activated if the battery voltage drops below the preset disconnect level during more than 12 seconds.”
The word “drops below” suggests a dynamic event (a transition), which could explain why the alarm doesn’t activate on startup.
A customer of mine reports that older BatteryProtect units always triggered the alarm regardless of startup conditions.
Is this behavior intentional by design, or is it a firmware bug?
Thanks in advance for any insight!