Pete DeMar, the co-founder of Battery Research and Testing, based in the US, opines on the value of the latest battery gas recombiners, which add two-way valves to the catalysts used for recombining the gasses that can be released when charging flooded lead-acid batteries.
Here in the US, there is always an ongoing effort to reduce the costs of products and services. Those at the top of the management food chain are continually striving for reduced costs and increased profits.
In any industry that uses a lot of stationary batteries to support emergency loads— such as the telecom, utility, or data centre industries— there is a substantial amount of labour (think expense) with maintaining the electrolyte levels in the vented cells. This was one reason why, many years ago, when VRLA (valve-regulated lead-acid) batteries were introduced, they were often referred to as maintenance-free. What the marketing people really meant was, there was no need to regularly add water.
A side benefit was that the off-gassing was reduced when compared to a normal vented battery with standard vent assemblies. Fast forward to the present time, with there now being battery gas recombiners that advertise 98% efficiency, and is it possible to reduce, or eliminate completely, those labour costs for watering?
Everyone involved in maintaining stationary battery systems— from the manager to the technician that actually performs the water refilling process— understands there is a time element required when adding water to the cells, and that cannot be shortened. It is always going to require an amount of time to accomplish. If the time to perform that work can be reduced or eliminated, it will reduce the cost and increase the profits. Those are hot-button words to anyone watching costs and profits.
While that may not seem as important to a user that has a single string of batteries— as compared to someone that has thousands of batteries— there are still savings, no matter how many or how few batteries there are. Time is money and it applies equally to all.
While European users are very familiar with battery gas recombiners because they have been in use in Europe for fifty years now, they are a sort-of-new item here in the United States. I am guessing that they have not been really promoted or widely used over here for more than ten years. There are surely some users that have had recombiners installed for longer than that, but they are, by far, in the minority.
Because of the amount of experience in the EU, the European standards writing group addresses the difference in ventilation requirements (think water loss here) when recombiners are installed, as compared to batteries that have standard vent assemblies. This is explained in the UNE-EN IEC 62485-2 Safety requirements for secondary batteries and battery installations – Part 2: Stationary Batteries – 7.2 Ventilation requirements: Note 2. This states that if recombiners are installed in the cells, the ventilation requirements can be lowered by 50%. That allowance for a 50% reduction in the ventilation was made based on experiences with older-style recombiners. These did not have the two-way valves that are responsible for an improvement in the amount of gas that is recombined. As these valves result in a further reduction in the gasses allowed out of the cell, I wonder if they will look at the recombination efficiencies of the new recombiners and lower that ventilation requirement even further.
When utilities— be they of the telecom or the electric producing/transmitting groups— had more personnel than they really needed, it was not a big deal to dispatch people to go water a battery. However, the days of any company having ‘extra’ employees are long gone. Everyone is running as lean as possible and, sadly, with stationary batteries they often are ‘out of sight and out of mind’. When this happens, electrolyte-level maintenance is often skipped. This is referred to as the ‘we will get to that the next time syndrome’.
Here in the states, we have an organisation called NERC which stands for North American Electric Reliability Corporation. Of course, with the recent ‘oops’ situation in Texas, there might be a need for a disclaimer as to what they are and are not responsible for.
To explain that: some years ago, Texas made the decision not to be connected to the rest of the US grid with their transmission system. In February, an extreme cold system with temperatures below freezing went through the Southern US, and a large part of Texas lost power. People lost heat, pipes were freezing in houses, people had to abandon homes to get to shelters, and people died from exposure. As typical of the political leaders in Texas, they first tried to blame it on wind generators that did not function. The real culprit was the natural gas transmission lines were not properly insulated for such cold temperatures, and the gas could not be used.
NERC has jurisdiction, or a type of control, on mandating testing and maintenance of certain pieces of equipment that are a critical part of assuring the infrastructure (think power grid here) will function when needed. While the transmission lines were functioning, the generation group could not generate power.
The document that lists the testing requirements for all of the equipment they consider critical is the PRC-005-06 Standard Application Guide. The section that covers the DC equipment is Protection System Station DC Supply Maintenance Activities (Table 1-4(a) through Table 1-4(f). In this section in Table 1-4(a) there is a requirement for verifying that the electrolyte levels are within the acceptable range. The only exception to this is if there is a permanently installed monitoring system that continuously measures the electrolyte levels in the cells. Based upon this requirement, it can be assumed that even if the electrolyte level will not need to be refilled, someone still needs to physically go look at the cells. This is a real waste of time and is usually lumped in with other activities at that specific site on that specific day.
If the powers that be, either within NERC or the IEEE ESSB (Institute of Electrical and Electronics Engineers Energy Storage and Stationary Battery) committee, would look into the reduction in water loss, it might be possible that the time interval for checking electrolyte levels could be extended substantially, or possibly indefinitely.
Everyone in the stationary battery industry realises that a vented lead-acid cell far outlives a VRLA one, so it would seem there are a number of benefits to installing modern recombiners in vented cells.
There presently is an ongoing test intended to prove the efficiency of modern recombiners. That research paper is to be presented at the Battcon 2021 conference. With the data accumulated so far, it does look like the usage of the modern recombiners can eliminate the need to add water to any vented lead-acid cell that is in normal usage— for the life of the battery. By this, we mean more than twenty years.
