Path: utzoo!attcan!uunet!dalcs!lane From: lane@dalcs.UUCP (John Wright/Dr. Pat Lane) Newsgroups: comp.sys.ibm.pc Subject: Overcharging NiCad batteries? Keywords: NiCad rechargeable batteries, laptops, foreign power Message-ID: <3008@dalcs.UUCP> Date: 25 Sep 88 07:38:18 GMT Organization: Math, Stats & CS, Dalhousie University, Halifax, NS, Canada Lines: 68 I just noticed in the User's Manual for my Zenith 183 some rather critical operating information buried in the middle (well, on page 1 of chapter 3). And no, I didn't read the whole thing when I got the machine...shame on me :-) (seriously, it's the thickest, most detailed User's Guide for a computer I've ever seen). Anyway, they say that there is a considerable danger in overcharging the NiCad batteries and that repeated overcharging will reduce the length of time the batteries will hold a charge to virtually nil. They recommend charging for 8 to 10 hours and *no* more. I've, of course, been leaving mine plugged in virtually all the time (ulp!). Further, they say that damage can be done by charging the batteries before they are fully exhausted. They suggest the following operating cycle: 1. Run the thing on batteries alone till the battery low beeper sounds 2. Save your stuff and continue operating on batteries (listening to the annoying beep every few seconds!) until the screen goes (yeah, right!) 3. Then plug it in...it's unclear whether you have to save your stuff (if you can!) and turn it off at this point. To me, this sounds wierd as h*ll. Are they for real about this? I'd be interested to know how other people use their laptops and other NiCad battery operated equipment. I'd also be interested in hearing from the technically knowledgeable on the subject. Specific questions: 1. The 8 to 10 hours recharging time...is that affected by whether the machine is on? Would that mean that you should not use the machine on and plugged in for more than 10 hours...after 10 hours, unplug and use the batteries till they're gone, then go back to external power for another 10 hours and so on...till you give up and go get some sleep :-) 2. Should you plug and unlplug the external power while the machine is on or power down for the switch to and from batteries...if the latter, does this not make Zenith's advise about running on batteries till the machine packs it in rather risky for saving your work? 3. Would this all not apply equally to all equipment using NiCad's (such as the Diconex 150 I also use)...funny this is the first place I've seen these warnings. 4. As I said, I've been leaving my machine plugged in alot, while I'm using it and otherwise, and I'm getting about two hours on batteries before it starts beeping at me. Given the relatively large backlit screen and 20Meg HD, this did not seem that unreasonable and I've notice no degradation in this since I got the machine but I wonder if I should be getting longer battery life. Side issue: I have a car cigarette-lighter adapter as well. The instructions warn against having the laptop on and plugged in when starting the vehicle which seems sensible. They also say that the battery cannot be charged while the machine is on when running from a car battery because there is not enough power. I was curious about this because (I could be wrong here) I thought the regular ext. power adapter supplies 12V-DC and if the voltage is the same, would the laptop not try to draw enough amps to run the machine and charge the batteries both? How would the machine know it was in a car? Another side issue: A friend with the same system is going to Europe and was wondering about his options. We both thought it should be safe to use one of those cheap voltage converters (that do not change the 50 cycle line frequency) with the external power adapter (which converts the juice to DC so the freq. should not matter) for both charging the batteries and actually running. Are we right? Sorry about the length of the article and appreciate any advise/comments. -- John Wright ///////////////// Phone: 902-424-3805 or 902-424-6527 Post: c/o Dr Pat Lane, Biology Dept, Dalhousie U, Halifax N.S., CANADA B3H-4H8 Cdn/Bitnet: lane@cs.dal.cdn Arpa: lane%dalcs.uucp@uunet.uu.net Uucp: lane@dalcs.uucp or {uunet,watmath,utai,garfield}!dalcs!lane