logant@lafcol.UUCP (Tracy Logan) (11/19/89)
I am looking for a solar-energy driven battery charger, either as a commercial product or as a schematic. For NiCad batteries. Thanks for any suggestions. -tracy [ uucp: rutgers!lafcol!logant | BITNET: LOGANT@LAFAYETT ]
commgrp@silver.bacs.indiana.edu (11/20/89)
>I am looking for a solar-energy driven battery charger, either as >a commercial product or as a schematic. For NiCad batteries. >Thanks for any suggestions. >-tracy [ uucp: rutgers!lafcol!logant | BITNET: LOGANT@LAFAYETT ] Rule of thumb for charging NiCd cells is to use constant current at 10% of cells' ampere-hour capacity, for 16 hours, e.g., charge 1-Ah cells at 100 mA. If the solar cells' maximum output current is around 10% of the NiCd capacity, and the output voltage is somewhat above that of the NiCd battery, the charging circuit isn't critical; just hook it up. Remember to put a silicon diode in series to block reverse leakage through the solar array when it's dark, and remember that about 0.6 volt is lost in the diode's forward conduction. _Radio Electronics_ described a novel solar power supply in the August 1989 issue (p. 47) in which four large solar cells in series charge a single 1.25v NiCd cell, which powers a switching-regulator circuit which steps the voltage up to 9v. -- Frank Reid W9MKV reid@gold.bacs.indiana.edu
vaso@mips.COM (Vaso Bovan) (11/20/89)
In article <7200043@silver> commgrp@silver.bacs.indiana.edu writes: > >>I am looking for a solar-energy driven battery charger, either as >>a commercial product or as a schematic. For NiCad batteries. > >Rule of thumb for charging NiCd cells is to use constant current at >10% of cells' ampere-hour capacity, for 16 hours, e.g., charge 1-Ah >cells at 100 mA. Remember to put a silicon diode in series to block reverse >leakage through the solar array when it's dark, and remember that >about 0.6 volt is lost in the diode's forward conduction. > Germanium diodes (0.3V) and some schottky diodes are more efficient than silicon diodes in low voltage charging circuits. For very low current applications, "signal" rather than "rectifier" germanium diodes work just fine. Check the specs though; germanium diodes have temperature limitations.
brianr@tekig5.PEN.TEK.COM (Brian Rhodefer) (11/21/89)
In article <31730@buckaroo.mips.COM> vaso@mips.COM (Vaso Bovan) writes: >In article <7200043@silver> commgrp@silver.bacs.indiana.edu writes: >> >>Remember to put a silicon diode in series to block ... reverse leakage, >>and remember that about 0.6 volt is lost in the diode's forward conduction. > >Germanium diodes (0.3V) and some schottky diodes are more efficient than >silicon diodes in low voltage charging circuits. Power MOSFETs are available with on-resistances down into the tens of milliohms nowadays. One of these, with suitable CMOS "smarts" to make it imitate a rectifier, would cut the forward losses below even those obtainable with germanium diodes. Brian Rhodefer
cook@stout.ucar.edu (Forrest Cook) (11/22/89)
In article <7200043@silver> commgrp@silver.bacs.indiana.edu writes: >>I am looking for a solar-energy driven battery charger, ... >Remember to put a silicon diode in series to block reverse >leakage through the solar array when it's dark, and remember that >about 0.6 volt is lost in the diode's forward conduction. For a slightly more efficient setup, use a schottky diode, the drop is around .3 volts or so and you should be able to find one that can handle moderate current. DigiKey has some in their catalog. ^ ^ Forrest Cook - Beware of programmers who carry screwdrivers - LB /|\ /|\ cook@stout.ucar.edu (The preceeding was all my OPINION) /|\ /|\ {husc6|rutgers|ames|gatech}!ncar!stout!cook /|\ /|\ {uunet|ucbvax|allegra|cbosgd}!nbires!ncar!stout!cook
johnson@ncrons.StPaul.NCR.COM (Wayne D. Johnson) (11/23/89)
>>I am looking for a solar-energy driven battery charger,
I seem to remember seeing a solar battery charger for a car at our
local TARGET store. It cost about $30 and claimed to re-charge your
car's battery through the cigarette lighter.
If Target has them, they should be showing up in Kmart, Wall-Mart, and
most other discount stores as well as auto parts stores.
--
Wayne Johnson | Is a baby's life worth more than the right to
NCR Comten, Inc. | make a choice? Babies are people too.
Roseville MN 55113 +-----------------------------------------------------
(Voice) 612-638-7665 (E-MAIL) W.Johnson@StPaul.NCR.COM