kWeld – laser cut housing kit
kCap – laser cut housing kit

kCap ultracapacitor module



NOTE: if you purchase this article together with a pre-order article, they will be shipped together.

Notice to U.S. customers! We are busy setting up a local warehouse with regional support. An assortment of keenlab products is currently in stock at our local US warehouse. If you are interested, please contact:

The assembly and operation manual is available on this website for download:

This module features six Maxwell BCAP0310-P270-T10 ultracapacitors, delivering more than 1000A of pulse current to the kWeld system.

Connect a suitable power supply to the inputs of the module (e.g. the kSupply module), and the kWeld to its output terminals to create a stationery spot welding solution. Because it is modular, you can easily change back the system into a portable welder.

The power delivery capacity of the module of up to 5kW enables the use of this module can be used for a variety of other demanding applications.

IMPORTANT NOTICE: the module is not protected against overvoltage – the rated voltage of 8.1V must be observed. As the ultracapacitors are filled with a liquid electrolyte, overcharging them can lead to their destruction.

The key specifications are:

  • six Maxwell BCAP0310 cells in a 3S2P configuration
  • rated voltage 8.1V
  • pack capacity 206F / 6780Ws
  • internal resistance 3.3 milliOhms
  • typical short circuit current 2400A
  • maximum power delivery 5000W (into a 3.3 milliOhm load)
  • advanced balancing circuit that keeps all cells within +-50mV at all charging levels
  • temperature monitoring and control of an optional 120mm fan
  • separate input and output terminals (for ring cable lugs, with holes for M5 screws)
  • LED indication for balancer activity and temperature sensor
  • fully protected against voltage spikes from inductive kickback from welding
  • dimensions 110 x 110 x 47mm

Performance when used with kWeld:

  • maximum continuous repetition rate with kWeld (50J pulses):
    • once every 4 seconds without fan cooling
    • once every 2 seconds with a Scythe Slip Stream SY1225SL12SH fan mounted (not included in the kit)
  • typical welding current 1100A
  • maximum usable welding pulse energy 100J

This product comes in two different flavors:

Without capacitors: you receive the circuit board with all components soldered – except for the BCAP0310 capacitors, in case you wish to source the capacitors by yourself and plan to solder them onto the board.

Complete: you receive a complete board that is ready to go, including two connecting cables (AWG8 with crimped cable lugs on both ends) that replace the stock kWeld battery cables.

Weight 0.6 kg
Dimensions 15 × 15 × 10 cm
completion grade

without capacitors, complete


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