Hi Assuming the supplies are rated for a (fairy normal) 32V max, there is plenty of room to get everything arranged right. You *might* need to dig up a supply that is 28V nominal versus 24V nominal. The 10 or 15% adjust range likely will not quite get the 24V unit up where you would want it to be. The (say) 29V supply goes to one of your voting diodes and runs the unit when it’s off battery. The other voting diode goes to the top end of the battery stack. Your charger circuit puts what ever it wants on the battery to keep it happy. Yes, when you go on battery you loose .7 V (or less) due to the diode. If you want to get fancy, put a FET across the diode and eliminate the diode drop once everything gets going.
The bigger question is - how do you disconnect the battery after it’s done its thing for long enough? Deep discharge of the cells is not good for them either. Yes this gets more complex by the minute …. where is that guy who was getting all preachy about keeping things simple :)….. Bob > On Oct 25, 2014, at 5:32 PM, Christopher Brown <[email protected]> wrote: > > > Might want to dial that back a bit. > > Since 12V/7ah batteries are mentioned I am assuming standard small > gelcell units. > > Proper float voltage for a deep cycle is lower than a SLI type, and > gellcell even lower. > > Generally 13.6 - 13.8 would be the gellcell range, with 13.6 being right > on for long life use of _small_ batteries. Equalizing charge wold be 14 > - 14.2. > > Floating a small gelcell at 13.6 (27.2) v.s. 14 can mean the diff > between 12 - 24 months v.s. 5 - 7 years service life. > > On 10/25/14, 11:39 AM, Tom Miller wrote: >> These units are ideal for powering via a float charged lead acid battery. >> Use two 12 volt / 7 AH batteries in series and adjust the regulated float >> power supply to 28.0 volts. Be sure to use a diode from the supply to the >> battery just in case the supply can't be back fed during a power fail. >> >> Tom >> >> >> >> ----- Original Message ----- >> From: "Bob Camp" <[email protected]> >> To: "Bob Stewart" <[email protected]> >> Cc: "Time Nuts" <[email protected]> >> Sent: Saturday, October 25, 2014 3:01 PM >> Subject: Re: [time-nuts] Lucent KS-24361/Z3812A GPSDO initial setup >> >> >>> Hi >>> >>> Spend the effort, get an antenna outside the house. Beg / borrow / steal a >>> UPS. Even a brand new one is less than you paid for the 3812. >>> >>> >>> Bob >>> >>> >>> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
