On Sun, 2007-07-29 at 08:25 -0500, Aaron Konstam wrote: > On Sun, 2007-07-29 at 19:03 +0930, Tim wrote: > > Tim: > > >> It's generally a good idea to make use of rechargable batteries - run > > >> the device they're meant for, using the batteries, from time to time. > > >> Quite apart from the technical reasons, of keeping the batteries > > >> alive, there's not much point owning them (and paying for them) if you > > >> don't make use of them. > > > > Aaron Konstam: > > > Au contraire , there is lots o reasons. One is when I am running the > > > machine at home for 3 hours with a battery that runs it for 2 hrs and 14 > > > minutes. On DELL D810 it is designed to run that way so why not? > > > > I'm not quite sure what you're disagreeing with. > > > > One of my points was that I don't see much sense in paying for a battery > > if you're not going to use it as a battery, they're not cheap. That > > doesn't mean you have to use it all the time, but using some times would > > do it good. > > > > Batteries generally last the best when made use of. Ones that sit there > > unused, or always being charged, usually suffer. Ones that sit in > > equipment are often slightly discharging through the equipment, and > > being trickled charged, constantly. Consider yourself lucky if yours is > > fine in those conditions. > > > > Chargers are *sometimes* are fine to leave connected, as *some* are > > designed *not* to keep on charging a battery needlessly. Others are not > > so intelligently designed. (Whether that be the box you plug into the > > wall, or circuitry in the laptop between battery and the power brick.) > > > > Some laptops are not really good to run continuously, they may have not > > so brilliant cooling. They may use a laptop drive that's been designed > > to last being turned on and off a lot, but not so much for continuous > > running. The opposite of most desktop drives. > > > > There's a multitude f factors, and it's hard to say what's best for > > some, it's even harder to attempt to say what's best for all. > > > I have a terrible urge to send replies to your private address even if > they are rejected. > > So what are you suggesting. That when I run the laptop on power I remove > the battery. Well here is my didactic statement for the day. I would not > buy a laptop that could not be run on wall power even if the battery is > installed. I always thought Toshiba made high class laptops. If I found > my Toshiba laptop needed to have the battery removed when I ran it on > wall power I would sell it the next day. Would you buy a cell phone that > did not stop charging when the battery was fully charged. I would not. > We are in the 21th century and we know how to construct a device with a > battery that works correctly. > -- Unfortunately, Aaron, no one knows how to defeat the basic physics that make batteries work. Each form of battery has its own quirks, and the longest lasting ones and most robust are phosphate based lithium ion. And they appear to have a charge cycle rating of about 10000 (about 10x a lead acid battery and about 3x that of a nimh.) The purity of the materials, the physical construction, and the form of interaction that charges and discharges the battery all have effects that limit the life in one form or another. Chargers are all designed to put current through the battery, which with luck and proper design reverses the chemical reaction, resulting in charging. Some of that energy is lost in heat, in building internal fields, in fighting the resistance of the materials in the battery and connections, so the process is lossy, and generates heat in ways that are also limiting to the battery's operation. In short nothing lasts forever. There are very good tutorials on the Trojan Battery website: http://www.trojan-battery.com/ And here is the link to the Wikipedia entry about nimh: http://en.wikipedia.org/wiki/Nickel_metal_hydride_battery And from the Wikipedia, the reference for DuraCell NiMH: http://www.duracell.com/oem/rechargeable/Nickel/nickel_metal_tech.asp Another source, for the lithium phosphate technology is: http://www.valence.com/ Note that the Valence technology is a relative newcomer and quite expensive, but it is literally the bulletproof battery, and you can read on their website about why shorts do not affect them and see the photograph and test results of a bullet penetrated battery. In short all battery have batteries have two major limitations: aging reducing capacity and cycle lifetime, typically rated at the 50% capacity life. With daily cycling the goal is currently 3 years, with most batteries reaching two or slightly longer. Continuously charging a battery develops a "memory" of shallow discharge, which shortens both cycle life and capacity. Hope this helps you understand the technical issues. Regards, Les H
