On 22 July 2014 15:36, James Cameron wrote: > On Mon, Jul 21, 2014 at 08:16:34PM -0700, Alan wrote: > > And also, from Zetex - in English. > > http://www.diodes.com/datasheets/ZXLD383.pdf > > > > These are nifty little things, they isolate the solar cell from the > > battery and turn on the light when dark. And all with a single > > NiCad. And with only one other part, a simple inductor. > > Agreed, a nifty design. > > Also explains why the units I've tested tend to chew up their NiMH > batteries quickly in the Australian desert; no discharge protection, > no overcharge protection. > > Caherg control is not the iC's concern. This can be implemented independently if desired. Some have enable pins which allow use of undervoltage cutout as well. Most of these ICs will enthusiastically suck essentially all the charge out of a battery (down to say 0.7V operation) so LV cutout is necessary in a serious product. Some US yard lights are changing to LiFePO4 and there are capable charger ICs available at OK prices. Bottom end one may use an eg TL431 to cut off charging completely when the battery reaches target voltage. This is effective in protecting against overcharge. It also eliminates the CV part of the CC CV charge cyclethereby reducing battery available capacity but extending battery life. LiFePO4 is different than LiIon in that you can 'safely' remain in CC and charge to much higher terminal voltages than the usual CV cutoff level, then drop out of CC with no CV stage. A TI LiFePO4 charger IC does this. I am unsure of the merits of this scheme and there is very little information (that I can find) on the underlying electrochemical aspects. This is of significant intertest IF it can be done without reducing cycle life. Doing this with LiIon would damage the battery rapidly and risk conflagration. Russell > -- > James Cameron > http://quozl.linux.org.au/ > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .