Troubleshooting

The order of checks

1. Stop and assess the hazard level.
   • Any sign of a hydrogen leak, fire, arcing, a burning smell, severe overheating or uncontrolled electrolyte leakage means stop at once and follow the emergency section of the safety chapter.
2. Make it safe before touching anything.
   • Ramp the stack current down to 0 A, then turn off the DC output.
   • Electrically isolate the DC supply from the stack and apply your site procedure to prevent accidental re-energisation.
   • Secure the external loop: confirm the vent and relief lines are safe and unobstructed, and manage residual pressure and electrolyte by your site procedures.
3. Record the as-found condition.
   • Record at minimum the stack current and voltage and the electrolyte flow and temperature.
   • Add hydrogen flow, pressure and purity and oxygen purity if you measured them.
   • Write down what you observed too: pump noise or cavitation, gurgling, an unstable wet outlet return, unusual vent behaviour, visible leakage.
4. Check the most likely external causes.
   • Flow and heat: valves open, tubing not kinked or blocked, no trapped air, tank level adequate; the filter not clogged if you use one, and cooling available at the heat exchanger.
   • Wet outlet and backpressure: no restriction or blockage in the OUT line, no kinks or pinches, and a stable return to the tank.
   • Electrical: DC cables tight, no discolouration or overheating marks, correct polarity and clean terminal contact.
   • Vent and relief: outlets not blocked, iced or covered, and nothing placed in front of them.
5. Apply one corrective action at a time.
   • Change one thing, check whether the symptom improves, then change the next. Change two together and you lose which one it was.
   • When you restart, begin at low current and confirm stable flow and a stable voltage trend before ramping up.
6. Know when to stop.
   • If the issue persists, repeats or suggests hardware damage, stop operating and contact us.
   • If you are unsure about the vent and relief routing, backpressure or the safe limits, ask us before continuing.
7. Document the outcome.
   • Write down what you changed and what happened. It prevents repeating the same misdiagnosis and speeds up our reply if you do contact us.

Find by symptom

Find the line for what you see, take the first action, then go to the section in the right-hand column. Lines run from most to least severe.

Symptom A: the voltage rises rapidly

At the same current the stack voltage climbs quickly or sits unusually high. Work through the four causes from the top.

1. The electrolyte temperature is too low

• Verify the temperature reading and confirm the heater is running: power, status, setpoint.
• Bring the temperature back into the normal range, typically around 50 °C.
• If the heater is not working or the temperature cannot be restored, stop and repair or replace the heater.
• If the voltage stays abnormal after the temperature is restored, contact us.

2. The electrolyte is too dilute

• Confirm the electrolyte specification is 0.1 M KOH and review the recent DI water make-up and refill history.
• If dilution is suspected, stop and replace it with fresh 0.1 M electrolyte.
• Restart at low current and confirm a stable voltage trend before ramping up.
• If the abnormal voltage persists with fresh electrolyte, contact us.

3. Internal crossover or membrane damage is suspected

• Stop operating.
• Record the evidence: the electrolyte level trend, the DI water make-up events, and the stack current and voltage.
• Contact us with those records. This is not something you can resolve on site.

4. The electrolyte flow is low or unstable

• Confirm the pump is powered and commanded on: the indicator or controller status, and the fuse or breaker where applicable.
• If the pump is on but there is no flow, it does not start reliably, or it behaves abnormally, stop and repair or replace it before resuming.
• Confirm all the relevant valves are open.
• Remove obvious restrictions: straighten kinked tubing, clear blockages, and check or clean the filter if you have one.
• Remove air from the loop and make sure the pump is properly primed.
• Restore a stable flow, 4 L/min as recommended.

5. A single cell voltage shoots up

• If you measure individual cell voltages, one cell climbs far above the others. If you do not, the stack voltage reaches the supply's limit and the current falls by itself although no setting was changed.
• In our tests a slow rise of stack voltage at the same current appeared first, 10–24 hours before the stop.
• Stop operating and do not restart repeatedly. Send us the current and voltage trends, and the cell voltages if you record them.

Symptom B: the voltage falls rapidly

At the same current the stack voltage drops quickly or sits unusually low. The causes fall on the opposite side from symptom A.

1. The electrolyte temperature is too high

• Verify the temperature reading.
• Restore temperature control: confirm cooling is available at the heat exchanger and the circulation is working.
• If the temperature cannot be controlled, stop and service or repair the external cooling and circulation equipment.

2. The electrolyte is too concentrated

• Check the tank level and verify the DI water make-up is working.
• Correct the electrolyte back to specification, 0.1 M KOH, by your site procedure.
• Restart at low current and confirm a stable voltage trend before ramping up.

3. The electrolyte flow is low or unstable

• Work through it the same way as cause 4 under symptom A: the pump, the valves, restrictions, trapped air, and restoring the flow.

4. An abnormal stack condition is suspected

• If the voltage stays unusually low after temperature, concentration and flow are all restored, stop operating.
• Record the evidence and contact us: the stack current and voltage trend, the electrolyte temperature, the flow, and the recent maintenance history.

When to contact us

• Abnormal voltage behaviour persists after you have restored the electrolyte flow, temperature control and condition.
• Leakage recurs despite correcting the fittings and tubing and confirming material compatibility.
• You suspect damage to the stack hardware: the ports, end plates, compression hardware or terminals.
• The same problem persists or recurs under normal operating conditions and the symptom guide does not resolve it.
• You are planning non-standard operation and want the safe limits and recommended practice confirmed.

What to send

Having the following ready speeds up diagnosis. If you kept the record at the end of the quick-start chapter, half of it is already done.

Before confirming a return we may ask for more data or troubleshoot remotely first. Once a return is confirmed we send packing and shipping instructions. Draining and packing the stack so it does not leak or corrode in transit is yours to do.