Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!purdue!iuvax!silver!commgrp
From: commgrp@silver.bacs.indiana.edu
Newsgroups: sci.electronics
Subject: Re: Photovoltaic charger for NiCads
Message-ID: <7200043@silver>
Date: 19 Nov 89 20:39:00 GMT
References: <1749@lafcol.UUCP>
Organization: Indiana University CSCI, Bloomington
Lines: 27
Nf-ID: #R:lafcol.UUCP:-174900:silver:7200043:000:1080
Nf-From: silver.bacs.indiana.edu!commgrp    Nov 19 15:39:00 1989




>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