The story of the Emperor’s new clothes is a classic example of how the message we need to hear can come from the most unexpected source. In this column, we look at a practical example from the 1990s battery industry.
As a species, we have an unfortunate tendency to be influenced more by the messenger than the message. In some situations, this is understandable, particularly when the message can be a highly technical argument that the recipient is not qualified to understand. The only recourse, in that case, is to look at what we can understand, which is often the confidence and decisiveness of the person giving the message. We associate confidence and being definite with competence, simply because we assume that to be confident a person must know what they are doing. However, this is sadly, all too often, not the case. In fact, long experience in industry has shown me that those who are definite are very often definitely wrong. This is a problem in many organisations; good ideas or talent can be overlooked, particularly in group meetings, because we tend to look to the messenger rather than the message.
In this article, we have an industrial lead-acid battery manufacturer (surprise!) from the 1990s, specialising in military supply. The starting point is a meeting called by the MD (Tony) to discuss a report sent to them by a customer who purchased batteries for diesel-electric submarines. They had a new problem with unequal cell charging and acid stratification in some of the batteries’ 2V cells. This resulted in some cells producing potentially explosive hydrogen gas (H2). This was despite venting when the boat was on the surface using the diesel engines to charge the batteries. There was a real possibility that there may be a sufficient concentration of H2 in localised areas (more than 4%) to form a combustible mix. Information supplied by the customer showed that the gassing had been traced to central cells in the battery. The mechanism for this was explained by myself at the meeting. It was due to the higher temperatures of the central cells. This reduces the hydrogen overvoltage on lead— which means H2 increased as temperature increased.
The 10 am meeting began with Alan the sales director reading the report sent by their customer, describing the nature and extent of the problem. Apart from Tony the MD, the other people present at the meeting were the heads and key staff from all relevant departments. The important players for this narrative were Stuart the engineering manager with his assistant Jim, myself as technical manager, Arthur the production manager and Alastair from accounts. After Alan had read the report Tony asked for responses from the group of managers. It took a couple of minutes before Stuart, the Engineering manager piped up with his usual hubris.
“Looks like we have to solve another customer’s problem for them… yet again!”
He was immediately taken to task by the MD Tony: “The main reason we have this business, which, by the way, is the most profitable of all our accounts, is precisely because we offer more than just a product. Our whole ethos and current upturn in fortunes are due to our customer partnership philosophy. We work with them and don’t abandon them when they run into difficulties. Now let’s kick off and get a programme started to resolve this”
There was a good start with the technicians and engineers discussing the traditional solutions for ensuring cells were equally charged. These were based on fitting intercell balancing resistances with sensors and automatic regulation of individual cell-string voltages within the pack. These would also be linked to temperature sensors to switch current on and off in individual series strings. This was expensive and complex. Tony was clearly uneasy with the direction the meeting was taking and after a break for lunch asked the group to try and think of less onerous solutions.
There followed a tense few seconds of silence when a quiet and hesitant voice began to speak after clearing the throat. It was Jim, the projects engineer, someone that Stuart relied on heavily but would never admit it.
“Well, we need to know why this hasn’t come up before since we’ve been supplying this company with the same batteries for the past four years.”
He looked embarrassed after his answer, then folded his hands on his midriff and put his head down, as if waiting for a derogatory comment. After some delay, the MD spoke and asked Jim why that was important. The answer was perfectly logical— we had to ascertain if there were battery faults or new conditions not seen before. If so, we needed to take these factors into consideration before devising a solution. Alan the sales director, confirmed that the customer had no information that would shed any light on this. They were also insisting that their operational conditions were the same but would not disclose details of their operating profile. Jim nodded and concluded that they had no option but to run some tests, preferably on board the sub and/or in laboratory simulation trials.
This last statement had the effect of a bee sting on Stuart who immediately jumped to his feet.
“What are you saying? How many times are we going to put this strain on the engineering department? What about the new curing ovens being delivered this week, the overhaul of the spine casting machines and the new oxide transport system in the tube filling department? We are already stretched to the limit. And furthermore, what will this study tell us? We can’t redesign the batteries; we can’t change the charging system or the operating conditions. It’s a pointless exercise. Let’s ignore this. Jim has more brains than sense. We need realism; that’s not his strong point!”
Tony made a hand gesture to Stuart to sit down. After a long pause, he looked around the room. “Any other opinions or suggestions?”
I decided to throw my support behind Jim on this matter. It was always better to be aware of the cause of a problem whether or not it can be fixed. At the very least we could advise the customer how to manage it, and measure the impact on their operations. Then, if they decided to live with it, we could offer a regular maintenance service which would be chargeable. At this point, we were in the precarious land of conjecture; we needed to get some data before we could hope to find a solution. To this end, a small team, working part-time taken from the engineering and technical departments, should come up with the definitive position in a few weeks if we pull our fingers out.
Tony raised a hand, to silence Stuart’s second rant before it started. He agreed we had to do it, but gave us a fortnight, not a few weeks, to come up with the cause or causes of this battery glitch. That same day we arranged a meeting with a team of four: two engineers (Jim plus Ted— the electronic maintenance guy) and two technicians, myself and Janice— the quality assurance/laboratory manager. The plan was to fit temperature and voltage sensors in the central and end cells of the installed battery in order to identify when and how much the differences arose during the charging periods. A sticking point came when the question was asked as to how we would identify the point when the gassing started in the cells.
After over 20 minutes of fruitless effort, every idea was rejected. It was at that point that Jim asked the question:
“When the cells produce gas, is it in the form of bubbles? If so, do they make a noise?”
This got the team into overdrive. After much arguing, a proposal to fit a microphone to the inner and outermost cells was devised. It would be linked to a processor, able to distinguish the noise of the bubbles from the background noise. The sensitivity and accuracy were key issues, but Janice said she should be able to rig something up. Based on this, a test jig was made within a couple of days. Background noise simulation was provided, the cell was attached to a power source and the voltage ramped up to a level where gassing within the cell started. It took time, but we achieved over 90% accuracy in identifying the gassing onset.
The total test equipment was fitted within a week of the instruction. Details of the battery room construction were provided including the interior ventilation pipes. By the end of the following week, there were sufficient results to identify the nature of the problem. It was basically this:
• The heating of the cells was not generated entirely by the charging process. There was another source of heat.
• This heat source was a ventilation pipe above the centre of the battery which drew in air from the upper floor. This pipe was enclosed by the exhaust pipes from the engine. This heated the air passing through the pipe before it entered the room, right above the centre of the battery banks.
• The maximum temperature difference across the battery was 15°C between the centre and outer cells. Laboratory tests showed that this was enough to lower the hydrogen overvoltage on the battery plates to enable gassing to occur.
The difference was too much to compensate by charging at a lower voltage. This was a unique feature that explained why they had not seen it before. Unfortunately, it was part of the construction of the submarines and could not be altered. Another meeting was called to discuss the implications of the field tests. Tony asked me to present the results to the department heads at a meeting, and invite the team to propose measures to resolve the problem. There was a lukewarm response to the question of what measures could we employ to eradicate, or at least reduce, the voltage difference.
After an hour of head-scratching and rejected ideas, throughout which Stuart had been ominously quiet, Jim the mechanical engineer, suggested two things: a heat sink to be placed in the centre of the pack and a fan in the battery compartment directed at the heat sink. The heat sink would consist of steel sheets pushed down the sides of the cells with finned heat exchangers attached to the sheets above the cells. A fan would blow air across the cooling fins and draw heat away from the cells. There was a swift response from Stuart: “Jim, you know nothing about batteries and chemistry. You are a mechanical engineer; you should stick to what you know best: tightening nuts and fixing conveyor belts”
I had to wade in at this point: “Calculations show that the cooling method would equalise the difference between the middle and end cell temperatures to within around 2-3 degrees difference. It should work.”
Stuart was not finished: “And what about the practicalities? These cells are a metre high with less than a metre headspace above them. How do we remove the wood packing and then slide these sheets vertically downwards? We would have to disassemble every battery in every sub. It would take months, even if the subs were available for this time. It’s bloody daft!”
Jim was prepared for this. Still keeping his head bowed to avoid the gaze of others, he very quietly explained how it would work: The wooden spacers between the cells in the middle of the battery could be pulled up to their maximum clearance, then use a portable saw to cut off the protruding section. This would allow the remaining part of the spacer to be removed. To insert the heat sink, the metal sheets would be constructed in sections and joined by small bolts through predrilled holes as they were lowered into the slots left by the removed spacers. Stuart started to speak again but was unceremoniously silenced by Tony who had clearly had enough of these interruptions. The MD then asked for more detail on how this would be implemented.
Based on the field study report, simulation trials would be carried out in the factory on smaller batteries that would take one week to set up and another week to verify the effectiveness of this method. The trials would involve the use of the engineering and production departments and their staff, to make a small-scale prototype with a reduced number of cells (250 in the full submarine battery compartment) consisting of the following:
- Steel sheets with finned Aluminium heat exchangers on the top
- Fans to blow across the battery
- A steel container to house the reduced number of full-sized submarine cells
- The fan direction would be along the longest path in the connected strings, with two rows of cells on either side of the row containing the cooled cells.
With the consent of the MD, the prototype set-up was constructed within a week. The trials over 10 days showed that the temperature difference of 12°C was reduced to 3°C between inner and outer cells. Further calculations showed that this reduced temperature difference would be maintained, even with a full-size battery in a submarine. The trial method was used in one of the customer’s submarines over a month. The maximum temperature difference recorded was slightly under 3°C. This was adopted by the customer, who acknowledged the contribution of their ventilation design to the cause of the battery gassing. A fee was agreed to implement this on all the submarines which gave the company’s sales a welcome boost.
Another consequence was that the battery company had an internal reorganisation. A new development team was created with Jim promoted to team leader reporting directly to the MD. This would help to develop new business opportunities and resolve any customer difficulties within the existing business. Stuart found himself with a smaller department with responsibility for maintenance and equipment installation (tightening nuts and mending conveyor belts). Over the next couple of years, the company not only kept its existing military contracts but also won a further two tenders for new market applications. The moral is to evaluate the message, not the impression left by the messenger.