DKblock – An industrial strength modular system to package and protect lithium-ion cells for battery packs in mobile and stationary applications

This site is dedicated to the open source industrial strength lithium-based battery management and packaging system called DKblock2. The DKblock2 is a battery pack building block that combines 18650 cell packaging and an Offgrid-approved or user-supplied battery management system (BMS) and can be used to build a battery pack from 6.2VDC to almost 60VDC (and beyond with user-supplied BMS) without any welding.

You can only lose what you cling to.
— Buddha

Let’s look at the major pieces of a DKblock2 battery pack system, then we’ll look at the parts needed to build one battery block. There are 3 major pieces of a DKblock2 system, which are 1) two clamp boards to make one lithium-based cell block, 2) the BMS Connection PCB and 3) the BMS, which talk to each block and manage the cells. There is one BMS per pack, and there is one BMS Connection PCB per DKblock, and there can be virtually any number of blocks in one pack. For example, a 48V pack would require 7 lithium-ion DKblocks at minimum, since each Li-ion DKblock is 7.4V nominal and 7×7.4=51.8VDC. So lets look at the parts need for just one DKblock for a system of any voltage.

The cell holders:

2 cell holders are required for each DKblock2, both holders are identical

These parts are made with a polycarbonate ABS (PC-ABS) thermoplastic polymer blend called Makrolon 6485 which is UL94 rated for high temperature and low flammability, and two identical pieces of them are required to build one DKblock2. Also, there is hardware required to hold the blocks together, screws and standoffs.

Now we take a look at the other five different parts required to make one DKblock

First we need stainless steel screws and aluminum standoffs…

Next we need two different circuit boards with special gold plated spring clips capable of 8 amps continuous (15 amps peak) with special 20 amp PCB fuses for each cell

One each 2S-3.7V board and one each 2S-7.4-0V board needed

Then, we need one more circuit board and some screws…

Four 2-28 stainless screws needed to fasten BMS connection board to block

One BMS connection PCB needed for each DKblock2 in a battery pack for battery management system (BMS) to connect to battery cells. If you buy the Offgrid kit, the boards will come pre-wired and pre-jumpered. If you DIY your own BMS, you will wire and jumper your own boards.

Last we need some battery cells…

Before assembling the basic DKblock2, the lithium cells must be acquired and tested. These can be purchased as new or salvaged cells. Here is also a discussion about choosing proper battery cells on the Offgrid GitHub .

For a really good primer on the workings of the lithium-ion battery checkout Adam Bender’s excellent website.