Maxwell 350 Farad 2.5V Ultracapacitor High Current PCB Connection Style

Basic specs:

  • Capacitance 350 farads
  • DC Equivalent Series Resistance (ESR) 3.2 milliohm
  • AC Equivalent Series Resistance (ESR) 1.6 milliohm
  • Short Circuit Current 1687 Amps
  • Max Peak Current (1 sec) 220 Amps
  • Absolute Max Voltage 2.85V
  • Operating Temperature Range -40 to +65 degrees C
  • Stored energy 1275 joules (.354 WH)
  • Max Power 976 Watts
  • Connections PCB solder pins
  • Weight 2.1 oz (60 grams)
  • Diameter 1.3 inches (33 mm)
  • Length 2.44 inches (62 mm)

You can solder the ucap in a PCB or solder directly to the pins to make connections.
They are basically the same size as an ordinary D cell flashlight battery.
They were intended for use in high reliability wind turbine blade pitch control applications.

These are the high current PCB connection style. Unlike many competing styles with wire leads, the hefty tin plated copper pins have negligible resistance, so they can deliver the full rated 1687 amps of short circuit current without problem.

Click HERE to see the Maxwell data on this item.

Click HERE and then click on DOWNLOAD to see a large number of Maxwell references, explanations and application notes.

And HERE for a fairly technical article on using ultracaps in energy harvesting applications, plus some useful info on leakage current versus time and temperature.

Click HERE for a short note on converting electrical energy units to mechanical energy units.

One important application for these devices is for electric vehicle regenerative braking. Due to their ability to quickly charge and discharge, they can recover 80% or more of the car’s energy that would otherwise be lost in heat. Batteries generally can recover less than 30% of this energy due to their limited charge acceptance.

Another application is the storage of solar energy. Many solar applications (garden lights, for instance) quickly fail due to the poor life expectancy of the battery in repeated charge/discharge cycles, poor charge control, and temperature cycling. Ultracapacitors are largely immune to these problems. These ultracapacitors can be combined in series for more voltage or parallel for more current. They ought to be good for solar related projects such as remote sensor power, solar lighting, solar electric gates, etc

HERE is a very good website dedicated to ultracaps with a lot of useful info, theory and tips. HERE is a video of someone who used 6 of these ucaps to completely replace his car battery! And HERE is a good description of how using just three 10 farad capacitors made possible the production of a battery powered tubing cutter, with an explanation of the circuit used. HERE you can see an entertaining video of how to destroy nails and coins with ucaps.

Click HERE to see an interesting web page by someone who made a pool lighting system using solar panels and ultracapacitors.

They are also beginning to be used in space satellite applications due to their robust design and superior life expectancy over batteries. And now they are in the new Peugeot cars for stop/start systems. See
for an article on this application.

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