Back about 20 years ago, NiCd batteries were notorious for having a pronounced memory effect caused by a special type of crystal formation within the battery. This particular mechanism has been eliminated in current NiCd cells but our memory of it, so to speak, is long.

Today's batteries all have some kind of memory in which the capacity of the battery changes with patterns and depths of discharge. Each type of battery chemistry exhibits this effect for different reasons - some types stronger than others. Unfortunately, it's also referred to as a "memory effect" which is confusing to those of us who remember the old "memory effect." Nothing like calling two different things by the same name to generate a lot of confusion!

Because this effect varies with battery type, blanket statements about it are unwise. Isidor Buchmann's *excellent* and very readable book, Batteries In a Portable World, and its sibling website, www.batteryuniversity.com, tackle the full spectrum of battery types and how to apply them. On the website, I highly recommend taking the opportunity to read the section "How to Prolong Battery Life." The book is available from the ARRL Store and other book sellers. Both should put a charge into your understanding of this important energy source that is crucial to effective emcomm operation. Good luck and may your batteries live long and prosper!

-- Ward Silver, N0AX, Contributing Editor, QST; ARRL Contest Update Editor; St. Charles, Missouri

www.arrl.org/ares-el?issue=2013-03-20#toc02