Batteries and the Future of Smart Grid Technology

The increasing adoption of renewable electric sources as well as EVs has reached a pace where the existing power infrastructure needs to start changing. This will affect nearly everyone from businesses down to individual residences.

In 2021, in the US 20.1% of the power was generated from renewable energy resources. This is good news for the reduction of greenhouse gasses and reducing our reliance on fossil fuels. However, the increasing adoption of renewable electric sources as well as EVs has reached a pace where the existing power infrastructure needs to start changing. This will affect nearly everyone from businesses down to individual residences, and here’s why. Renewables are generally intermittent and the only economical way to accommodate that today is by selling that power to existing power plant generators and letting them moderate the ups and downs by adjusting their output. It’s a very centralized top-down approach and it will continue to work for a little while longer, but not in the long term.

The Rise in Rechargeable Battery Power

As renewables increase, at some point power companies won’t be able to handle the quantity of producers – which also increasingly includes individual producers. Economically, the ultimate solution is to have levels of “aggregators” that will take all of these smaller producers and bundle them together. They will then distribute that power to the local users through a smaller smart grid and also sell up the chain to the conventional producer when they have excess power. Power storage now becomes a key element of the grid infrastructure since more people are buying EVs and local battery storage to ensure continuity of power locally.

Expertise in power management and in battery management systems will become a key growth factor for this new power distribution model. A limited number of companies are focused and have the capability to address these power management needs. It requires not only the understanding of battery charge/discharge behavior but also how to handle these large amounts of power safely.

Moving the Industry Forward

Figure 1 Prototype Cable Assembly

Interconnect Solutions Company (ISC) has been one of the more active participants on several fronts when it comes to developing the physical charging interface. They have developed and tested pre-production prototypes for heavy-duty lead-acid batteries for scissors lifts and fork trucks as well as charging plugins for passenger EVs. ISC over the last fifty years has developed unique capabilities and expertise in the electronic packaging and cable assembly business.

In the industrial markets, this translates to ruggedized cables with overmolded backshells for UV and strain relief protection. Generally, these will also be well sealed against moisture intrusion (up to IP68), resistant to chemicals, and won’t degrade when exposed to extreme temperatures. With ISC’s capability to fabricate custom cables, they are a one-stop shop for new designs of cable assemblies.

Battery Types Make a Difference

One critical consideration is that charging profiles for sealed lead-acid (SLA) batteries, the kind that most people are familiar with for automotive and similar applications, is different than the newer Lithium-Ion (Li-ion) used to power EVs. SLA batteries are charged in three stages: bulk, absorption, and float. In the bulk stage charging voltage ramps from 12.5 volts to 14.5 volts. This drives current into the battery until it reaches about 80% of capacity. In the bulk phase, once the current flow is within about 10% of the charger’s total output, it moves to the float stage and stabilizes at 13.5 volts. Chargers for SLA batteries are designed around these inherent characteristics of lead-acid chemistry.

By contrast, Li-ion batteries’ discharge characteristics are pretty much constant voltage. At 100% charge, a Li-ion battery will hold its voltage around 13.3 – 13.4 V. At 20% capacity, it will still be at 13V. By contrast, the SLA battery at the same capacity will be around 11.8V. Since Li-ion batteries are essentially constant voltage devices, they require a different charging strategy. Li-ion chargers are based on a Constant Voltage/Constant Current (CVCC) algorithm. They tightly control the current flow until the voltage reaches a certain level and then the current tapers off until the battery charge is full. This results in a faster charging cycle than SLA batteries. The differences are more than academic. Using the wrong charger type can result in permanent battery damage.

Not Just Windmills and Electric Cars

Figure 2 Forklift Charger connection

In industrial and commercial settings particularly warehouse forklifts and scissors-type man lifts, SLA batteries are still preferred. Among other attributes (like cold start capabilities), the battery weight is significant and helps contribute to the overall stability of the device. Especially when using a forklift, having just the right amount of counter-balance weight is crucial to safe operation. It’s clear that as battery storage moves toward Li-ion, there will be a need for both types for the foreseeable future.

Putting it All Together

Like all electrical systems, proper connectivity strategies optimize the availability of power and minimize downtime. The ISC design team has years of experience in providing well-designed and engineered cabling and connecting products for these purposes. Their unique value is their experience in combining smart cables, customized cable assemblies, and reliable connection strategies together into a well-packaged, easy-to-use power management system. Whether it’s a manual connector for charging a bank of Li-ion batteries for an EV or a 500-pound SLA battery system for an industrial fork truck, ISC has the design and fabrication tools to do the job. From short-run prototypes all the way up to full production design, ISC can provide the quality needed to ensure smart power management solutions.

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