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Building Blocks

‘s Building Blocks are a unique blend of latest battery technology, safety and ease of use. Each block is made of several 3.6V 18650 Li-ion cells connected in parallel. Several such blocks may be connected in parallel and series to form high voltage battery packs of various shapes and sizes.

Each block comes with various options:

  • Single row or double row
  • Cell count up to 10 per row
  • Optional multi-point temperature sensor
  • Various 18650 cell models

Why building blocks?

  • The easiest to use 18650 solution on market
  • Up to date with latest battery developments
  • Easy bolt connections for rapid prototyping
  • Cell-level fuses for prevention of thermal runaway
  • Gas release channels for handling of critical events
  • Built in cell-level temperature sensing for specialty applications
  • Ready for thermal management with air-cooling

Cylindric form factor is arguably the best Li-ion battery cell solution today, as it offers unrivaled quality, safety and latest developments in battery technology. However, these cells come with several drawbacks due to their shape and small size: cylindric shape is asking for special trays, non-tabbed contacts require complicated busbar welding techniques, and small size is very labor-intensive to build a large battery pack with thousands of cells. On top of this, there are plenty of safety-related issues that need to be taken care of and usually this must be done by very skilled engineers, with many years of experience in the field. All of this can be managed by large automotive companies, however smaller ones are typically overwhelmed by these difficulties and opt for different solutions, like pouch and prismatic cells. Even large automotive companies don’t get it right the first time, or often look for an easier option straight away. Due to these reasons very few electric car models use cylindric battery cells, even though they offer clear benefits.

building blocks combine the best of two worlds – low weight, high power, quality, safety and ease of use.

Why 18650?

Lithium-ion batteries were developed in 1970s, and mass production began in 1990s, mainly for use in consumer devices, such as laptop computers. Li-ion cells have in many cases replaced NiMH and NiCd batteries and were in rapid development, especially in cylindrical 18650 form. These numbers represent cell’s size of 18mm in diameter and 65mm in length. There are new standards being developed in recent years, like 21700, however cylindric form factor is still preferred by many companies.

High power and energy density

Even though a cylinder may seem as not effective use of space at a first glance, the internal conductors are very tightly rolled and often offer higher energy density per volume and weight than competition, even per whole pack, counting in the air gaps among cylinders. No need for compression plates gives yet another way to save some space and weight. Resulting air gaps also offer an opportunity of easy and effective thermal management solution, either by liquid or air.

Up to date

18650 is still the most popular standard and cells are available from all the major companies, such as Samsung, Sony/Murata, LG, Panasonic, Sanyo and others. Each year new models are being released with ever growing energy capacity and power handling, representing the latest developments in battery technology. This allows the customer to pick a new cell each year without any extra costs: no redesign of the battery pack or change in tooling. New batch can be produced using new cells right away.


Due to long history and well established manufacturing techniques, these cells offer very high quality and almost unbelievably low fail rates of only 0.01 per million, which becomes very important when battery pack is built from thousands of cells.

Stable manufacturing process leads to high tolerances and low parameter deviation. Typically cells measure below 3mV of voltage difference even after years in storage, which means very little maintenance and balancing is needed. This allows the use of cost-effective and reliable battery management systems with low balancing current: 5mA bleeder on a 200Ah pack is often acceptable. This also means that all building blocks made by are in perfect balance once delivered. In contrary, initial balancing of poor quality cells may take weeks or even months, usually asking for special equipment for initial conditioning of battery pack.


18650s are housed in a self-contained metal shell, which requires no special treatment, like mechanical compression used for pouch cells, or swell compensation used for pouch and prismatic cells, which complicates overall design and construction of battery pack.

Each cell is also equipped with a bimetallic fuse and a pressure release valve to manage critical events such as short circuit or mechanical damage, on top of already robust metal shell.