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Project: Mini-D
Date:June 2009

Note: This project has been superseded by Da Pimp which can desulphate, test and charge batteries of different voltages.


Mini-D is a desulfator designed to be used with 12V lead-acid batteries. This device can restore new life to batteries which have been sitting without a charge for extended periods of time.

Desulfation removes sulfur crystals that have formed around the lead plates. On a 12V battery sulfur crystals begin to form when a battery is stored at a voltage of less than 12.3V. These crystals are undesirable as they cause resistance within the battery which eventually leads to a battery unable to pass current. Mini-D breaks the crystals by emitting a high frequency / high voltage / low power pulse which creates a resonance inside the battery.

I have desulfated and sold dozens of lead-acid batteries. A batteries improvement can be measured by applying a load to the battery periodically and watching the voltage drop. A 60lb battery will take roughly three weeks to desulfate.





  1. schematic (pdf)
  2. src (html)
  3. src (bz2 tarball)
  4. gerbers (zip)
  5. schematic (gschem format)
  6. pcb (pcb format)