Kevin Parmenter, Director, Applications Engineering. TSC, America
The need for energy storage is growing tremendously, and battery applications are everywhere – from cell phones to handheld power tools, to electric vehicles using grids tied to alternative energy. Meanwhile, the boundaries between storage cells and supercapacitors are getting blurred. Supercapacitors are taking over the jobs previously done by battery cells, such as in memory retention applications. The science of energy storage for both batteries and supercapacitors is highly interdisciplinary. Essentially the process is still electrochemical in nature, yet there are manifold engineering aspects to consider, such as form factor, volumetric efficiency, reliability and, especially, safety.
Safety is a key in battery applications because the energy they contain can be very high indeed, which means short circuit conditions can result in exothermic events (fire) during shipping and use. Moreover, the manufacturability of the product must be taken into consideration at the outset of the design, including liability concerns in case something goes wrong with the battery itself. Additionally, when batteries are designed into products, charging times must also be considered. This includes measuring voltage and current and temperature, and also modulating the charging time and the voltage and current applied versus the measured temperature.
Actually, battery control is a common design theme regardless of the battery chemistry used. And the need for control is increasing as charging-time expectations are compressed. Drivers want their EVs to recharge as fast as cars are filled at gas stations. Although a lofty goal, advances in power electronics as well as a variety of new battery chemistries, are making super-fast-charging possible in the future, without damaging the storage device in the process.
Uninterruptible power supplies are one area shifting to higher levels of energy-storage techniques, such as from sealed lead acid batteries to Li-ion. But changes in battery technologies can present challenges. I had a recent project, for instance, where the UPS system wouldn’t power up correctly upon delivery. Even after following the startup instructions to the letter, the 48-volt battery pack had zero volts out. I couldn’t reach support hotline due to time zone differences, so I started to troubleshoot why the new, out-of-the-box UPS had no power.
It turned out that the (unnamed) UPS supplier probably changed the crimp connectors from a high-quality connector supplier to cheaper “same thing” parts. The good news is that the supplier went above and beyond on the failure analysis and sent new packs and (very heavy) UPSs overnight. The sad news is that state-of-the-art battery and power technology can be derailed by someone deciding to save fractions of a penny.
In the end, the cost savings on the inexpensive connectors was far eclipsed by the shipping charges to correct the problem – plus, what if the wires had touched during shipping? As we become more dependent on increasing energy storage, we must do better understanding the total costs vs. safety benefits of battery technologies. In the beginning there is price at the end there is cost.