Hi Bob The UT+ data sheet from 1998 quotes an external backup supply of 2.5 to 5.35V with a drain of 5uA typical at 2.5 Volts. Regards Nigel GM8PZR In a message dated 02/11/2014 20:41:44 GMT Standard Time, kb8tq@n1k.org writes: Hi The numbers quoted earlier (and they sound right) were 20 uA at 2.5V. That would be well under your 100uA. My *guess* is that self discharge / aging on a normal AA is going to limit things faster than a 20 uA drain. Now, if you have the more normal tiny coin cell involved with 1/10 or 1/100 that capacity and much lower self discharge …. Bob > On Nov 2, 2014, at 3:17 PM, Hal Murray <hmurray@megapathdsl.net> wrote: > >> By the way the z3801 is off most of the year so the drains quite small. > > I think that's backwards. The battery is only used when there is no power to > the GPS module. > > AAs are roughly 2800 mA hours. There are 8760 hours in a year. That's 319 > microamp years. (How's that for a SI unit?) So that's 3 years if your GPS > module takes 100 uA. I think that's way high. Anybody measured it? There > is probably a strong temperature component. > > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > 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. _______________________________________________ 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.

Hi So then the question becomes - What is the real cutoff voltage? Your pair of AA’s will start off at 3.1V, but they will get to 2.5 long before they are truly dead. Is the RAM gone at 2.5000 or 2.4 or “about 2 volts” …. Bob > On Nov 2, 2014, at 3:54 PM, GandalfG8--- via time-nuts <time-nuts@febo.com> wrote: > > Hi Bob > > The UT+ data sheet from 1998 quotes an external backup supply of 2.5 to > 5.35V with a drain of 5uA typical at 2.5 Volts. > > Regards > > Nigel > GM8PZR > > > In a message dated 02/11/2014 20:41:44 GMT Standard Time, kb8tq@n1k.org > writes: > > Hi > > The numbers quoted earlier (and they sound right) were 20 uA at 2.5V. That > would be well under your 100uA. My *guess* is that self discharge / aging > on a normal AA is going to limit things faster than a 20 uA drain. > > Now, if you have the more normal tiny coin cell involved with 1/10 or > 1/100 that capacity and much lower self discharge …. > > Bob > >> On Nov 2, 2014, at 3:17 PM, Hal Murray <hmurray@megapathdsl.net> wrote: >> >>> By the way the z3801 is off most of the year so the drains quite small. >> >> I think that's backwards. The battery is only used when there is no > power to >> the GPS module. >> >> AAs are roughly 2800 mA hours. There are 8760 hours in a year. That's > 319 >> microamp years. (How's that for a SI unit?) So that's 3 years if your > GPS >> module takes 100 uA. I think that's way high. Anybody measured it? > There >> is probably a strong temperature component. >> >> >> -- >> These are my opinions. I hate spam. >> >> >> >> _______________________________________________ >> 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. > > _______________________________________________ > 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. > _______________________________________________ > 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.