The PowerBank-50 Space Battery
by TakeMe2Space

Our vision, what gets us to work each morning, is building large orbital compute capacity or gigawatt-scale data centres in space. 

Every now and then we get positive reinforcement from unexpected quarters that recharges our batteries, but more about that later. Speaking of batteries, power is a major constraint, alongside radiation protection and thermal management, when it comes to realising data centres in space. 

Building a reliable and robust power system is essential for ODCs and we started by building one from the ground up. Here is more about the PowerBank-50, our space-proven and certified 50Wh battery for satellites.

PowerBank-50 - A 50 Wh Li Ion Battery Pack

A single PowerBank-50 flew onboard Skyroot’s first Vikram 1 test flight ‘Aagaman’ on 18th July, 2026. It powered Cosmoserve Space’s Mission Embrace payload, which is an active debris removal technology demonstration, shortly after the 4th stage of Vikram 1, the Orbit Adjustment Module, cut off its final engine burn at an altitude of 450 km. This is the battery pack’s first in-orbit demonstration of delivering power to a system after surviving harsh launch conditions and the vacuum of space.

A battery is more than a collection of electrochemical cells. It is an integrated energy storage system comprising cells, electronics, thermal management, protection circuitry, and software that together ensure safe, reliable operation. The complexity of the system scales with the operating environment. 

In space, batteries must withstand intense radiation, repeated thermal cycling from roughly +70°C to -40°C every 90 minutes, vacuum, microgravity, and the impossibility of repair or replacement. Every aspect of the battery system—from cell chemistry and packaging to battery management and thermal control—must be engineered to survive one of the harshest operating environments imaginable.

So here is a list of things that Simran, Vivaswan, Gaurav, Siva, Firoz and the team did to design and manufacture batteries to survive and thrive in the environment of low Earth orbit.

The journey of building our first space battery pack

• Finding genuine space-worthy cells. 

  The very first challenge was surprisingly basic: sourcing authentic lithium-ion cells. The market is flooded with counterfeit and re-labelled cells, and battery performance is only as good as the cells you start with. Establishing a trusted supply chain was the foundation for everything that followed.

  
  

• Selecting the right pack configuration. 

  With four cells to work with, we had to choose between a 2S2P or a 4S1P setup. Originally, a 2S2P configuration (7.2 V nominal) was selected, as most of our satellite subsystems ran primarily on 5V and 3.3V rails. However, as our mission architecture matured and power demands increased, many subsystems migrated toward 12V rails. This shift made the 4S1P configuration (14.4 V nominal) significantly more favorable. To offer maximum flexibility, we engineered our design so that both variants are available within the same form factor.

  
  

• Understanding how the battery actually behaves in space. 

  One of our earliest questions was deceptively simple: Would the battery get hotter while charging or while discharging? Charging happens in sunlight, while discharging occurs in eclipse, where the spacecraft is cold. After extensive testing, we found that the battery and electronics heat up significantly more during charging. That single insight drove a major design decision—we switched from a PEEK enclosure to aluminium because its thermal conductivity allows heat to escape much more effectively.

  
  

• Packaging an entire battery management system into an impossibly small volume. 

  Four 18650 cells already occupy most of a standard CubeSat battery pack. The remaining space had to accommodate charging electronics, protection circuitry, sensors and connectors. A single PCB wasn't enough, so the electronics had to be split across two boards while still carrying high currents safely between them.

  
  

• Designing for modularity from day one.

  We wanted users to stack multiple battery packs together to increase capacity and power output. That meant finding side-mounted board-to-board connectors that could survive repeated stacking while maintaining reliable electrical contact. Our first choice didn't perform well enough and had to be replaced in the next hardware revision. 

Examples of how multiple PowerBank-50 can connect to each other and to an EPS. Our MOI-1 6U CubeSat uses 4 packs (200 Wh). Up to 10 packs can be stacked together for a total storage capacity of 500 Wh. 

• Making thermal control affordable. 

  Batteries cannot simply be allowed to freeze in orbit, so every cell requires a heater. The challenge is building a reliable, affordable and preferably domestically manufacturable thermal control system for the battery pack.

  
  

• Designing a cell mounting system that survives launch and space. 

  The cells must remain firmly clamped through launch vibrations while still being free to expand and contract during thermal cycling and repeated charge-discharge cycles. Achieving both rigidity and compliance required several iterations of the mechanical design.

  
  

• Meeting outgassing requirements without creating electrical hazards. 

  The manufacturer's insulating sleeve on each cell had to be removed so heaters could be installed and outgassing requirements could be met. That introduced the challenge of ensuring there was absolutely no unintended electrical path between cells or to the enclosure.

  
  

• Fighting every gram of excess mass. 

  Four cells alone weigh around 200 grams. Everything else—the enclosure, PCBs, electronics, heaters and mounting hardware—had to be as light as possible. The final design adds only about 190 grams beyond the cells themselves.

  
  

Learning from testing and improving the design

Building hardware is an iterative process. Every prototype taught us something, and many of those lessons made their way into later versions.

• Correcting an easy-to-miss component selection mistake. 

  An early prototype used the wrong charger IC, one intended for lithium iron phosphate cells instead of lithium-ion cells. As a result, the batteries would only charge to 3.8 V instead of their intended 4.2 V, which was fixed on the next PCB revision.

  
  

• Reducing standby power dramatically. 

  Early versions consumed around 150 mW even while idle, forcing the batteries to self-discharge within a couple weeks. We then introduced a physical inhibit connector that disconnects the electronics during storage, reducing standby consumption to just 1 mW, which would keep the batteries charged for months. We also redesigned portions of the electronics to reduce active standby power by roughly three times.

  
  

• Making the battery intelligent and platform-independent. 

  Originally, the battery pack relied on the spacecraft's Electrical Power System (EPS) controller to manage charge settings, heaters and battery health. That worked inside our own architecture but created unnecessary work for customers who just needed the battery pack. We redesigned the battery to include its own low-power microcontroller unit (MCU), allowing any RS485-compatible spacecraft system (or even a laptop) to communicate with it while the battery handles its own management autonomously.

  
  

• Simplifying heater control. 

  The first design used a dedicated motor driver for battery heaters. Testing showed that approach wasn't ideal, so we moved to direct MCU-controlled closed-loop PWM heating, giving finer temperature control with lower complexity.

Thermal image of the battery heater testing

• Reducing mass after switching to aluminium. 

  Aluminium solved our thermal problem but doubled the enclosure mass from roughly 50 g to 100 g. To recover much of that penalty, we simulated various cutout designs to minimize mass on the enclosure, resulting in a reduction in mass by 20% without compromising stiffness and strength.

  
  

• Turning the enclosure into a thermal management system. 

  The top cover now doubles as a heatsink, allowing excess heat from both the electronics and battery cells to conduct into the spacecraft structure instead of remaining trapped inside the battery pack.

  
  

• Improving measurement accuracy. 

  One hardware revision focused almost entirely on refining current sensing, improving telemetry accuracy and battery monitoring through refined PCB layouts.

  
  

• Passing UN38.3 testing. 

  The final milestone was UN38.3 qualification—a comprehensive series of six tests that battery packs must pass before they can be shipped via air cargo. Thanks to the safety features and redundancies built into the design from the outset, the battery pack cleared these tests without difficulty.

  
  

Coming back to the positive reinforcement I mentioned at the start of this blog. The last few days have been incredible with the story of our battery packs – TakeMe2Space’s PowerBank-50 - going viral. What was unexpected was the Government of India’s Finance Minister tweeting about it. 

Building hardware is rarely about one breakthrough. It is about solving hundreds of small engineering problems, each one revealing the next. Looking back, what went viral wasn't just a battery pack. It was the culmination of countless design decisions, failed prototypes, test data, and engineering persistence. That's what makes building hardware so rewarding.

Browse all our satellite products here.