At the Resilient Living Campus in Pine River, MN, technicians have developed a system that optimizes lead-acid batteries used for solar energy storage.
Wiring Matters. At the Hunt Utilities Group Resilient Living Campus, batteries are arranged in various configurations, and tested for output, recharge and long-term performance. The goal is to "socialize" lead-acid batteries to optimize longevity.“We’re interested in both home storage and RV systems,” notes Dan Pavek, the young technician studying battery dynamics at Hunt Utilities Group’s research center. We're standing in the "ManiShop," a passive solar warehouse-sized building with a living roof and more other green features than I can easily list here. “A large RV has about six big batteries in it," Pavek continues, "and we’re hearing from owners that they typically get only three years of solar storage before they have to replace them. We want to try to double that." Pavek knows this isn’t the end game for cleaning up the footprint of battery storage, but he sees it as an important upgrade that will bridge the gap to other, cleaner forms of batteries now in development—such as algae or silicon-based technology. The group's approach to lead-acid batteries is sophisticated. It's easiest to pull a little of their online explanation. Among the challenges they're trying to address in their solar-heated ManiShop research building:
1.Batteries in series or in parallel must be well balanced or they destroy one another. If one battery begins to fail, it is stressed the most, accelerating the failure process. This can result in a catastrophic failure, and possibly fire or property damage.(3) 2.Under current practices, batteries cannot be swapped out individually, the whole bank must be replaced. This generally is a large expense to the owner of the system. Batteries in series are only as good as the weakest battery installed. For instance; If you add a new 100% capacity to a bank that the other batteries can only put out 80% capacity, then the new battery will end up chronically undercharged; shortening its life. The older cells become the new weak cell and deteriorate quickly, as well. 3. Lead Acid cells require careful charging and maintenance to maximize their life cycle. Most systems require a technician to manually analyze, monitor and perform this maintenance, with significant labor expense.(3) 4.All types of batteries have their own maintenance requirements and charging parameters. Technicians and engineers have to be specially trained for each type of battery that they are required to maintain. Traditional Battery Bus Wiring Traditional battery bus systems require heavy conductors and connectors which are capable of handling the maximum current of the batteries. Typical applications today employ batteries that are wired in series, or some combination of series/parallel.A key point the researchers make is that "Batteries in series are only as good as the weakest battery in the bank." As is often the case in home building, sometimes the most significant advance in efficiency is the one right under our noses. Too often, for example, builders focus on higher level engineering details such as R-value and glazings before addressing big design impacts such as siting and building orientation. In the case of batteries, this research seeks to demonstrate, less efficient wiring methods and lack of individual monitoring of batteries can lead to early failure. The end result of this research is something called The Battery Socializer networking system. To my understanding, it's not yet commercially available, but should be soon:
Unlike traditional battery banks in use today that are only as good as the weakest battery, the Battery Socializer employs microprocessor control of each battery along with a voltage abstraction system to monitor, optimally maintain, and protect each battery in the bank individually. The result is extended battery life, the ability to replace only defective batteries, add capacity as needed, as well as the ability to mix batteries of different types and conditions.Learn more about HUG's research. For more about resilient housing and homes that are "ready for anything," visit Resilient Times website. Image: Green Builder Media