Osaka Tubular sulphation — Hard Sulphate Locked onto the Plates

What it means: This is a symptom identifier, not an Osaka fault code — Osaka publishes no fault-code list for its tubular line, so SolarNevs names these pages after the condition itself. Lead sulphate forms on the plates during every normal discharge and dissolves again on charge. Sulphation is the damaging version of that. Rolls' manual defines it as large lead-sulphate crystals that will not readily convert back to normal material when the battery is charged, and lists three ways it happens — a battery stored too long discharged, a battery that is never fully charged, or electrolyte that has become abnormally low through overcharging or evaporation. A sulphated battery has less working plate area, so it charges quickly to a high voltage, reads full on a voltmeter, and then runs flat in an hour.

Why does Osaka (Pakistan Accumulators) show sulphation?

The Pakistan factor

This is the failure mode that kills most Pakistani tubular banks, and it is nearly always an installation and sizing decision rather than a manufacturing defect. An undersized bank on a load-shedding schedule is deep-discharged every evening and then given a partial recharge before the next outage. Osaka's own data sheet says a constant-current charge takes 12 to 13 hours to complete at 0.1C10, and a bank on a Pakistani duty cycle rarely gets twelve uninterrupted hours of charging at any point in its life. Owners blame the brand at year two. The honest answer is usually that the bank was too small for the load and never once reached 1.260. This also matters for money — evidence of routine deep discharge is the standard ground for a dealer to reject a warranty claim, so the fix is correct sizing and correct charge settings before it is an argument at the shop.

How to fix it

  1. Confirm it before treating it. Rolls describes two tells — the bank rises to bulk or absorption voltage unusually fast and the charger drops out early, and the cell gravities vary by more than 0.025 to 0.030 after a completed charge.
  2. Fix the cause before the symptom, or it comes straight back. That means the charge voltage, the absorption time, and whether the bank actually gets a full charge between outages at all.
  3. Ask your installer to run a corrective equalization. Rolls' procedure is a full bulk and absorption charge to 100 percent first, then a steady low current of 5-10 percent of the C/20 capacity, with per-cell gravity recorded throughout.
  4. Two hard limits your installer must respect. Rolls says do not equalize a bank with a known failed or missing battery, because the overcharge lands on the surviving cells, and terminate the process if cell temperature rises above 46 degrees C and approaches 52 degrees C. EnerSys' flooded manual sets an even more conservative bar for its own cells — stop the charge immediately if the battery exceeds 43 degrees C.
  5. Expect partial recovery at best. Rolls says that if the gravities plateau for 45-60 minutes without reaching specification, stop, let the bank cycle normally for two to four weeks, and repeat rather than pushing on.
  6. Do not run equalizations on a schedule just in case. Rolls is explicit that frequent equalization of batteries that do not need it overcharges and deteriorates the cells and shortens battery life.
  7. Do not buy a desulphator gadget or an acid additive to avoid this conversation. EnerSys' manuals allow nothing but approved water into the cells and warn that additives may void your warranty. If a supervised equalization does not bring the gravity back, the plates are finished and the battery needs replacing.

References