1. The open circuit voltage is low, and it will quickly drop to the termination voltage when discharging;
2. When a large current is discharged, the terminal voltage will quickly drop to 0;
3. The specific gravity of the electrolyte is very low when the circuit is open;
4. When the battery is charging, the voltage rises very slowly and always keeps a low value;
5. When the battery is charged, the specific gravity of the electrolyte rises very slowly and hardly changes;
6. When the battery is charged, the electrolyte does not bubble or bubbles very late.
