For a given size (and circuit board footprint) a supercap will have much less capacity and it has an exponential voltage decay curve, so it might have plenty of charge but not at a voltage that will hold the data. This usually means hours, not days of backup. A good rechargeable lithium will last several years, maybe longer as there will be no charge/discharge, maintains voltage until it is nearly exhausted, and can hold the data for days or weeks. On Wed, May 9, 2012 at 12:55 PM, Dave Taht wrote: > On Wed, May 9, 2012 at 9:47 AM, Eric S. Raymond wrote: > > Dave Taht : > >> What would be the change in cost and delay in manufacturing to switch to > >> using a supercap, rather than battery? > > > > Why would a supercap be better? > > Effective lifetime of... forever. no need for replacement. insanely > fast recharge. smaller (probably). What's not to like? > > I am not in a huge hurry to get into manufacturing, and I merely > wanted to cost out what what it would do to the bom, any changes to > the PCB, and get an estimate for the time it would take to do. I think > it will bump the unit cost up slightly, > but what price, forever? > > > -- > > Eric S. Raymond > > > > -- > Dave Täht > SKYPE: davetaht > US Tel: 1-239-829-5608 > http://www.bufferbloat.net > _______________________________________________ > Thumbgps-devel mailing list > Thumbgps-devel@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/thumbgps-devel >