BATTERY — How to Handle Battery (Cont'd) — Sulphation + Specific Gravity Check (Base K11)
EL-17prose procedureBattery sulphation + SG check (base K11). Sulphation if SG<1.100. Always temperature-correct SG to 20°C via SEL197P chart. Hot reads low (correct up), cold reads high (correct down).
How to Handle Battery (Cont'd)
SULPHATION
When a battery has been left unattended for a long period of time and has a specific gravity of less than 1.100, it will be completely discharged, resulting in sulphation on the cell plates.
Compared with a battery discharged under normal conditions, the current flow in a 'sulphated' battery is not as smooth although its voltage is high during the initial stage of charging, as shown in the figure at the left.
SPECIFIC GRAVITY CHECK
- 1Read hydrometer and thermometer indications at eye level. • When electrolyte level is too low, tilt battery case to raise it for easy measurement.
- 2Convert into specific gravity at 20°C (68°F). Example: • When electrolyte temperature is 35°C (95°F) and specific gravity of electrolyte is 1.230, converted specific gravity at 20°C (68°F) is 1.240. • When electrolyte temperature is 0°C (32°F) and specific gravity of electrolyte is 1.210, converted specific gravity at 20°C (68°F) is 1.196.
NOTE
Sulphation threshold: SG < 1.100 = fully discharged + sulphated. Always temperature-correct the SG reading to 20°C using the SEL197P chart — electrolyte SG drops with temperature, so a cold reading reads artificially low. The two worked examples show the correction sign: hot electrolyte (35°C) reads LOW so corrected UP (1.230→1.240); cold electrolyte (0°C) reads HIGH so corrected DOWN (1.210→1.196).