Adding Capacity to a Pylontech Lithium Battery Bank

Batteries can be the most expensive part of a power system, and the reality is that people's needs and circumstances change over time. Whether that's due to a growing business or a desire to reduce your system's generator run time to zero, the ability to expand a 13kWh bank into a 20kWh bank - without hassle - can be invaluable. 

Imagine a young couple that is expecting to have a family. They buy a vehicle that is slightly larger than what they currently need. The first child arrives, and they still have plenty of capacity. Eight months later, however, they learn they're expecting twins. Wouldn't it be great if they could add a third row to their compact SUV? 

In a communicating Pylontech battery bank, you can start with what you need now and expand capacity as your needs grow. This provides tremendous peace of mind and flexibility, knowing that you're not committing to a fixed power level for the entire lifespan of the batteries. It also allows you to budget accordingly if, for example, you need power on a property to construct a house and want to expand the bank when you move in two years later.

Is this done, typically? Absolutely not. Most lithium batteries don't allow for adding a new module after being in the system for about a year. This is because lithium batteries experience increased internal resistance and decreased overall capacity as they age. However, Pylontech has addressed this issue by enabling active management in their battery management system (BMS). The Master battery in a parallel string of Pylontech batteries is capable of monitoring each battery's capacity and its ability to deliver or receive current. This ensures the safe and efficient distribution of loads based on each battery's needs. 

What happens when you add a new module to a bank of older Pylontech batteries? The new battery will compensate for any differences in capacity. This ensures that the older battery modules in the bank do not limit the capacity of the new module. It also prevents potentially dangerous scenarios where the new battery has a higher state of charge compared to the older batteries, causing them to attempt to equalize. This is why the process of adding a battery to most existing lithium battery banks is rather complicated, requiring equalization of each battery before installation or the manufacturer advises against it. 

Furthermore, Pylontech is committed to ensuring backward compatibility of their BMS firmware, allowing for easy integration of new batteries into existing banks without the need to connect a laptop to every individual battery to update its firmware. 

Together, this and other features unique to Pylontech's BMS make upgrading your battery bank's capacity not only possible but also beneficial. This puts Pylontech years ahead of most battery brands available to us in the United States. In a Pylontech battery bank, added complexity related to adding or replacing an individual module is eliminated, allowing system owners to confidently expand to needs not only today but two years, even ten years from now.

Related Articles: 

>>> Battery Communication: Closed vs. Open-Loop Communications

>>> Bad, Better, Best: Battery-Inverter Communications & Compatibility

>>> Active Management: Expect More From Your BMS

Have a question about your application? Shoot us a message here or reach out directly to mike@icmontana.com.