On 25/9/03, [EMAIL PROTECTED] disgorged: >I think you mean "the nonexistent memory effect". :-) There is an >enormous amount of misinformation floating about concerning NiCd (and >NiMH) cells, but the low-down is this: > >The "memory effect" has been demonstrated, but it's not easy to >achieve. You need to discharge the pack to the exact same level many >times in a row to do it. After a large number of such charge cycles, >you then try to discharge beyond that level -- and you will see a >marked voltage drop as you pass it. Modern cells probably aren't >susceptible to it anyway: it's been decades since this was discovered, >and that was in a solar powered satellite, which is why the repeated, >exactly equivalent discharges came about. > >A related issue is voltage depression due to lengthy overcharging. >This shows up when a pack has been on a slow charger for a very long >time (like, say, in a portable device that's always hooked up to the >mains, so the battery pack is being continuously charged). After >sufficient such abuse, the pack will be found to supply power at a >lower than normal voltage when you try to use it. > >Both of these conditions (memory effect and voltage depression) are >repaired in the same way: one full discharge/recharge cycle. > >In normal use, both NiCd and NiMH should be treated the same way: >charge them and use them as you see fit, but try not to leave them >connected to a charger "forever", and try to remember to run them down >in a controlled fashion now and then (say, every three or four >months), to reassure yourself that they're still working well. When >you do this, and discover that the pack lasts a significantly shorter >time than it used to, it's time to replace it before it fails on you >at a time of its own choosing. > >Both types of cell have limitations on the useful life you can expect, >in calendar time number of discharge/recharge cycles. (Note that if >you discharge and recharge needlessly, you're using up battery life!) > >For more information about rechargeable batteries, check out "Red" >Scholefield's excellent web site at <http://www.rcbatteryclinic.com/>. > >-tih
I've left the reply above unsnipped in case anyone missed the excellent info it conveys. Thanks Tom, I have learned a great deal there. What about Litium Ion batteries with regard to all the above.....? Thanks, Cheers, Cotty ___/\__ || (O) | People, Places, Pastiche ||=====| www.macads.co.uk/snaps _____________________________ Free UK Mac Ads www.macads.co.uk
