Date: Sat, 13 Oct 2001 17:06:53 -0400 From: "Paul Wright" <[EMAIL PROTECTED]> Subject: Lithium Batteries - charging, usage, adapting, etc.
Disclaimer # 1 - I am not a scientific expert in this. [but I play one on TV?] No, really. I worked with some of the experts though. Discliamer # 2 - This is based on my observations of general practice. There are sure to be some exceptions. I worked for a US government agency that had a fairly large safety program specifically for lithium batteries. Lithium batteries contain a significant amount of energy in a small package. Like anything else which that might describe (explosives, high pressure gasses, etc.) there are certain potential hazards. Early designs of lithium batteries were as happy delivering their energy as heat and noxious gasses as they were in putting out electricity. Things have improved over the years, largely by a triumph of development over design. Still, Apple had some problems 5 years ago. I think the most recent problems have been the fault of the chargers rather than the cells. Anyhow, modern lithium batteries, especially the rechargeable types, have an amazing amount of hidden technology incorporated. Even the little AAAs have monitoring circuitry built into them. These circuits do amazing things, considering their size and placement and obviously contain programmed functions. If you look at battery packs, do you notice that most have multiple contacts? Only two contacts are physically necessary for discharge/recharge. The rest provide safety and monitoring capabilities. Some are contacts that must have power to them before other contacts will allow the charging process to occur. Others monitor individual cells or modules for signs of reversing polarity (or other bad things) and will irreversibly shut down a battery pack that is malfunctioning. This is why most packs either work fine or not-at-all and may go from one state to the next in a single charge cycle. (There have been rumors that some packs were designed to be recharged X number of times and then shut down. Never proven. Now, if MS made battery packs I might believe it.) Designs are mostly proprietary. Even with the awesome power of the US government, we could only develop tests for what happened under certain conditions. The manufacturers would not tell us what was designed to happen under the hood. Oh, and apparently identical battery packs bought 6 months apart would have different cells and modules inside. The technology is still developing rapidly and manufacturers are incorporating it on the fly. So, anyhow, if you dismantle a battery pack and replace cells with apparently identical ones (even from the same company), the circuitry may not recognize the new cells (win 3.1 vs win 95 software). Or, if they do work, some of the safety features may not be compatible. You really don't want to melt down your fanny pack/bum bag. Anyhow, my points are thusly: The odds of a jerry rigged battery pack working are low. The chances of a safety problem are significant. If you can't afford an official battery, I suggest an external pack of unmodified cells with an approved charger. -----Paul----- ************************************************************** http://libretto.basiclink.com - Libretto mailing list http://libretto.basiclink.com/archive - Archives http://www.picante.com/~gtaylor/portable/faq.html - FAQ -------TO UNSUBSCRIBE------- Reply to any of the list messages. The reply mail should be addressed to: [EMAIL PROTECTED] - Then replace any text on the message's subject line: cmd:unsubscribe --------TO UNSUBSCRIBE DIGEST------ Do above but with this on subject line: cmd:unsubscribe digest **************************************************************
