On 3/15/2015 8:46 PM, Chris Albertson wrote: > I have one of these UT+ receivers. Backup is not a big deal. How long > will the power be off? Certainly not for days and weeks. The backup > battery only has to last a few seconds or maybe an hours or two. The real > problem with batteries is not how much energy they store but shelf life. > You have to change the 2032 over five to eight years or so just because of > shelf life. So some people are using "super capacitors" because these can > handle the few hours or few days of backup power and have a much longer > working lifetime r maybe 20 years or more. F
True, it's not a huge deal. The receiver would be in position-hold mode anyway, so I would have NTPd configured to send the receiver its known position and a few other configuration options. Everything else is easily retrievable from the GPS signal given a few minutes. Backups of several years are overkill for me, particularly because the ephemeris and almanac are only good for so long. Backup power in the minutes-to-hours range would be perfectly fine for me. My question was prompted mainly because I was seeking clarity as to the proper use of pin #1: I didn't want to connect a non-rechargeable battery if pin #1 was only intended for rechargeable batteries, as that might cause damage. If that were the case I could use a supercapacitor, but I wanted to be sure the pin (a) could supply power, which the manual didn't mention, and (b) was current-limiting, otherwise the supercapacitor would draw enormous currents and possibly cause damage. Fortunately, it seems that a coin-cell battery will work perfectly. Once the boards arrive I'll do some tests with the supercapacitor. Many thanks to all for your help. Cheers! -Pete _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.