Between the recent office move and keeping up with herds of cats, I’ve fallen a bit behind in reporting news in other areas. Work is still progressing on the Ultracap power supply. After some further testing of the cell-balancer circuit based on the TI TLV4112IP high-output-drive op-amp, I decided that, while working flawlessly otherwise, it was drawing too much current. I’ve been rethinking the need for dynamic cell balancing and have re-read a lot of the Maxwell technical documents. My new theory is that balancing may not be as essential as I originally believed in a very low current application such as a robot power supply. I now think it may be possible to get by without dynamic balancing provided I protect the cells from over-voltage conditions during the charging cycle with something simple like some zener diodes. Finding very low voltage zener diodes proved a bit of challenge but I finally found some 2.7v 1/2 watt devices made by Fairchild that may work. I’ve ordered a few and will post results of the new tests soon.

Meanwhile, the DPRG received word from the IRS that our application for 501(c)(3) status has been approved, so we’re an official not-for-profit corporation now. And it only took 20 years to get to this point. I missed a couple of weekly meetings because of the move and during that time, Ron and some other members have been working on the A/C compressor at the warehouse and managed to getting it running, so we should have cool air for the next few meetings. We may have heat too shortly, which will come in handy in a few more months.