Path: csiph.com!weretis.net!feeder6.news.weretis.net!news.glorb.com!peer03.iad!feed-me.highwinds-media.com!news.highwinds-media.com!spln!extra.newsguy.com!newsp.newsguy.com!drn From: Winfield Hill Newsgroups: sci.electronics.design Subject: Re: Simple Low Voltage Shut Down Date: 30 Mar 2017 14:31:40 -0700 Organization: Rowland Institute Lines: 31 Message-ID: References: <-vWdnXOqofBu8kDFnZ2dnUU7-RednZ2d@giganews.com> NNTP-Posting-Host: p330419941b90cf00d5d83e9022e0075a69271a28276b1365.newsdawg.com User-Agent: Direct Read News 5.60 X-Received-Bytes: 1668 X-Received-Body-CRC: 1404401661 Xref: csiph.com sci.electronics.design:454275 Tim Wescott wrote... > >On Thu, 30 Mar 2017 13:18:33 -0700, Winfield Hill wrote: > >> Tim Wescott wrote... >>> >>>Second, you want some hysteresis, or at a certain level of charge the >>>thing will start madly turning on and off. Without hysteresis the >>>current will get shut off, the battery voltage will rebound, the circuit >>>will turn on, the battery voltage will get pulled low, and the cycle >>>will repeat. >> >> True, but a 1-volt battery with no load doesn't rebound very much. If >> the hysteresis is, say, 0.25V, it should stay off. > >An Internet acquaintance of mine who used to be a battery engineer for GE >claimed that nearly-fully-discharged NiCd cells would rebound to 1.2V if >you gave them enough time, even if they couldn't deliver any significant >charge. > >But -- I'd have to test that theory on alkalines. Alkalines are rather different, in a useful way. Their open-circuit voltage drops from 1.55V to 1.0 or 0.9V, etc, as they're depleted, providing a convenient way to evaluate their condition. -- Thanks, - Win