Osaka Tubular boiling — Cells Gassing Violently and Battery Hot on Charge

⚠ DANGER — this fault involves lethal voltage. Do not attempt a DIY fix. Call a qualified technician.

What it means: This is a symptom identifier, not an Osaka fault code. Osaka's tubular batteries have no display and publish no fault codes, so SolarNevs names these pages after what you can hear, smell and feel. Here the battery is audibly bubbling, warm or hot to the touch, and giving off acid mist while it is on charge. Some gassing at the end of a charge is normal — EnerSys explains that most gassing occurs after the 80 percent point as charging current breaks water down into hydrogen and oxygen. What is not normal is heat alongside it. EnerSys' flooded manual instructs that if the battery exceeds 43 degrees C the charge must be stopped immediately and the temperature allowed to fall below 38 degrees C, and warns that ignoring this results in severe overcharge and damage to the cell. Rolls sets its hard ceiling at 52 degrees C and says to shut off charge and let the batteries cool at or near that point. Hot and gassing means the charge is out of control, and what is coming out of the vents is explosive.

Why does Osaka (Pakistan Accumulators) show boiling?

The Pakistan factor

A directly solar-charged lead-acid battery exploding is a documented Pakistani outcome, not a theoretical hazard, and local installations supply three of the ingredients cheaply: a battery room at 45 degrees C, a hybrid inverter left on the default charge profile a shop originally set for a flat-plate UPS battery, and no battery temperature sensor fitted because it costs a little extra. Osaka's charge specification is quoted at 25 degrees C, so a setting that is correct in February is an overcharge in June. The other local pattern worth naming is the bank in a closed store room or under a staircase — hydrogen is lighter than air and collects at the ceiling, and Rolls warns that concentrations in excess of 2-4 percent may be ignited by an electrical spark and are explosive.

How to fix it

  1. Stop the charge now. Turn off the charger, the inverter charging path or the PV input, whichever you can reach without leaning over the battery.
  2. Ventilate the room and step back. Do not smoke, use a lighter, or create a spark. If you smell rotten eggs, treat the space as unsafe, get people out and let it clear before returning. That smell means the bank is being badly overcharged, and the enclosure is full of hydrogen as well.
  3. Do not pour water on a hot battery, do not open the caps while it is bubbling hard, and do not aim a fan straight into the vents to cool it. Let it cool on its own with the charge off.
  4. Once it is properly cool, check the electrolyte level in every cell. If plates were exposed, read the dry-cells page — that is very likely why it overheated.
  5. Once the bank is cool enough to be near safely, compare the units. An infrared thermometer is the right tool and Rolls recommends exactly that for isolating a damaged cell. If you only have your hands, use the back of one hand and do not touch a battery that is still hot, wet with acid, swollen or cracked. If one unit is much hotter than its neighbours, Rolls treats that as a sign of a cell failure or short — the battery is the fault, not the charger. Do not put it back into service, and read the dead-cell page.
  6. Do not restart charging until your installer has read the actual charge settings against Osaka's data sheet and fitted a battery temperature sensor. Re-energising an overcharging bank because the power is out is how these end badly.
  7. If the case is swollen, cracked or leaking, or if a cover has lifted, stop completely. Do not charge it again at all. Read the bulging page and call the dealer.
  8. Never charge an Osaka tubular battery directly from a solar array with no charge controller in between. There is no BMS and no protection circuit inside a flooded battery to save you from a charger that will not stop.

References