Using REPT Battero Cells in Industrial Battery Energy Storage Systems

Input Data: What You Need Before Sizing

Before touching a calculator, gather the load profile. That means 15-minute intervals for at least a year, ideally two. Without that, your capacity figure is a guess. Also confirm the grid connection point: voltage class, available short-circuit power, and any export limits.

For REPT Battero cells, the Wending series offers 280–320 Ah. The exact capacity depends on the cell version and operating temperature. We use datasheet values but derate for real conditions: 25°C nominal, but Ukrainian sites often see 35°C in summer and -20°C in winter, so thermal management matters.

We also need the duty cycle: daily peak shaving, frequency regulation, or backup. Each changes the C-rate and cycle life. REPT cells are typically rated for 0.5C to 1C continuous, but we design for lower to extend life.

Power and Capacity Sizing: From kW to kWh

Start with the power requirement. If you need 1 MW for 2 hours, that's 2 MWh of capacity. But that's the gross figure. Subtract system losses: inverter efficiency (97-98%), transformer losses (1-2%), and auxiliary loads (cooling, BMS). Realistically, you need 5-10% more capacity.

For REPT 280 Ah cells, each cell holds about 0.896 kWh (3.2V nominal). A 2 MWh system needs roughly 2,232 cells. But you don't put them all in series; you build strings. With 280 Ah, a 1C rate is 280 A, which is high for a string. So we parallel cells or use lower C-rates.

We typically size for a 0.5C rate to balance cost and cycle life. For a 1 MW / 2 MWh system, that means 2 hours of discharge at 0.5C. Payback depends on the tariff spread; in Ukraine, with current prices, peak shaving can pay back in 4-6 years, but that's a rough figure.

Connection Topology: Where REPT Cells Sit

In a BESS, the cell is the smallest unit. Cells form modules, modules form strings, strings connect to a DC bus, then to a PCS (power conversion system), then to a transformer and the grid. REPT cells sit at the bottom of this hierarchy.

We use a centralized inverter for systems above 500 kW, or string inverters for smaller. For REPT cells, we typically use a 1500V DC bus to reduce current and cable losses. That means series strings of up to 400 cells (depending on voltage limits).

Liquid cooling is standard for these cells because they generate heat at 0.5C. We integrate cold plates between cells. The BMS monitors voltage, temperature, and current at the cell level. REPT cells have a good balance of internal resistance, but we still need a balancing strategy.

What goes wrong if you size badly? If you underestimate capacity, you get premature shutdown. If you overestimate, you waste capital. But worse: if you connect strings in parallel without proper current sharing, you get circulating currents that overheat cells. REPT cells have low variance, but still, use a battery management system that can handle parallel strings.

Incoming Inspection and Acceptance: What to Check

When you receive REPT Battero cells, don't just sign the delivery note. We inspect every batch: visual check for damage, voltage measurement of each cell, and internal resistance test. Cells should be within 5 mV of each other in voltage and within 10% in internal resistance.

Also check the manufacturing date. Cells older than 6 months may have higher self-discharge. We ask for the test report from REPT, but we also do our own sampling: charge a few cells to full, measure capacity, and compare to datasheet.

Acceptance criteria: capacity within 2% of nominal, internal resistance within spec, and no signs of electrolyte leakage. If anything is off, we document it and contact the supplier. We've seen good consistency from REPT, but you must do this.

Warranty, Service, and Spare Parts in Ukraine

REPT Battero offers a standard warranty, typically 10 years or 6,000 cycles, whichever comes first. But the warranty is only valid if the system is installed and operated per spec. We help with that. For Ukraine, we have access to spare parts, but not from a local warehouse. Lead time is 2-4 weeks for modules or BMS components.

Service is the tricky part. We are not a REPT service center, but we integrate and maintain systems. We have engineers who know these cells. For larger issues, we coordinate with the manufacturer's technical team remotely.

In practice, most failures are not cell failures but BMS or thermal issues. We stock spare BMS boards and sensors. For cells, we can source replacements, but it's not immediate. So we design with redundancy: each string has a spare slot.

We also provide remote monitoring and troubleshooting. If you have a system with REPT cells, we can take over the service contract. We've done that for several sites in Ukraine.