On 23 July 2014 04:27, Mike wrote: > RussellMc gmail.com> writes: > > Catalog/brochure for Taiyo Yuden hybrid battery / capacitors. > > These have been available since about 2010 AFAI. > > http://www.yuden.co.jp/productdata/catalog/en/capacitor03_e.pdf > > > > Useful capacity gain over 'conventional' double layer super caps. > > The 40F has a sub AA form-factor. > > > > http://www.yuden.co.jp/productdata/catalog/en/capacitor03_e.pdf > > > Someone seems to think they are a viable alternative to AA batteries: > > > https://www.kickstarter.com/projects/shawnpwest/30-second-charging-rechar= geable-battery > > Unfortunately it looks like he's suffering from He's suffering for "Solar > Freakin' Roadway" syndrome; his numbers don't seem to add up. > > That project was the catalyst for my post. I followed the trail from his claims (at unspecified capacitance) via various sites to the Taiyo Yuiden catalog. You could fit the smallest of the Toyo Yuden offerings in his casing with a little room to spare. The main issues I see are: - Max possible capacity is vastly down on his claimed 1150 mAh (3% range) - His regulator is probably linear so energy will be down again on max actually possible (1-1.5% range) - He has very little idea of what he is about so he is quite likely to do something that severely degrades capacitor life. Overcharge a risk. Undercharge a risk His claimed 30s charge violates Toyo Yuden spec for their 40F cap by about 2:1 and more for larger caps (Ichgmax increases slower than capacity does) His price of ~=3D $25 with charger is almost doable if he is buying 400F TY caps from Digikey in volume. But, then, his specs fall abysmally short. The caps have Vmax of 3.8BV and Vmin of 2.2V. Discharge them under Vmin and you will damage them to a greater or much greater extent. As his output is 1.5V he has 2.2-1.5 =3D 0.7V headroom for the regulator. = If he uses an LDO and not a 7805 or similar and does not use low voltage cutout the cap is in trouble. Vmx of 3.8V should also 'not be exceeded'. His prototype charging circuit appears to use a TO220 IC alone. If so, unless he has found a 3V8 regulator 'there will be trouble' of the under or overcharge variety. _________________ Discharging from 3V8 to 2V2 with all energy converted to 1.5V out at 100% efficiency. Available abs max =3D 190 Joule Claimed available 1150 mAh at 1.5V =3D 6210J. Abs max actual / Claimed =3D~ 3.1%. A linear regulator would about halve that. Capacitor required to provide claimed 1150 mAh at 1.5V under discharge as above and 100% conversion efficiency =3D 1300 F Biggest listed Taiyo Yuden =3D 270 F 4.8 required - > say 5 Size =3D 25mm dia x 40mm long . AAA dimensions 10.5 dia x 44.5 long So volume of caps to meet AA capacity at 100% conversion efficiency =3D 25^2 x 40 x 5 / (10.5^2 x 44.5) =3D~ 25 x AAA volume. _________ Sidekick says 76% probability of success http://sidekick.epfl.ch/campaign/298476022-30-second-charging-rechargeable-= battery ________________ I dropped him a note a day or 2 ago. No response, so far. Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .