Posted on 2 Comments

Active Ultracapacitor Balancing

Here’s another active balancing circuit for large ultracapacitor banks, this one is designed for a series string of 6, at 2.5v per capacitor.

Based on the design here, I have transcribed the circuit into Eagle & designed a PCB layout.

Ultracap Balancer Circuit
Ultracap Balancer Circuit – Click to Embiggen

As can be seen from the circuit diagram above, this is just 6 copies of the circuit from the above link, with screw terminals to attach to the capacitor string.

Ultracap Balancer PCB
Ultracap Balancer PCB

And here’s the PCB. the MOSFETs & OpAmps are very small SMT parts, so require a steady hand in soldering. This board can easily be etched by hand as there’s only 3 links on the top side. No need for a double sided PCB.

As always, the Eagle project files & my Eagle library collection are available below:


2 thoughts on “Active Ultracapacitor Balancing

  1. Hi,

    Many thanks for this. It’s really interesting stuff.
    Would it be possible for you to take a look at the links for the downloads? As they seem to be broken.

    Many thanks in advance.

    1. Hi CA,

      Apologies! The links are now fixed!


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