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Rockbox mail archiveSubject: Re: Battery usage indications?Re: Battery usage indications?
From: Andreas Zwirtes <zwirtes_at_gmx.de>
Date: Fri, 18 Oct 2002 03:37:10 +0200 Since my first set of batteries is slowly giving up after a year of intense usage, I tried the second one. The Archos didn't even spin up the hd with this set, even it was fully charged. That was due to the inner resistance of one defective cell. While trying to spin up, the over all supply voltage dropped below 4V (scope-metered). I've measured the capacity of the batteries and they all had abot 1420-1430mAh. Only one of them dropped slightly below, it had only 1350mAh. I thought that this wouldn't make much of a difference, but it did. In the beginning, they were all very bad, but three of them recovered after cycling them 10-15 times in a battery analyzer. The one with 1350 is dead and useless, even thogh it has (now) nearly full capacity. TO EVERYBODY: If you've got your second set still in the blister package, unpack it and use it minimum every 2-3 month (complete discharge/charge). So you keep it fresh and usefull. The one battery in my set very likely died from self-discharge. NOTE: You shouldn't replace one single battery in a set, if it is defective. That is for a good reason: In a normal fresh set of batteries, all batteries have very similar capacity and discharge behaviour. Once the batteries are empty, that causes the all-over battery voltage to go down very fast, because all of them are empty at once. If you replace only one, it will hold its voltage much longer than the others and also the voltage of the maybe 8/10 empty battery is much higher than the voltage of the empty ones. So the overall voltage of the pack is significantly higher than it should be. This makes the device think it has almost 3/4 empty batteries and calculate a wrong remaining time. Also the three other batteries are heavily drained before shutdown and it is very likely that they fail after a few cycles. This is a common "n-batteries in a row" problem. QUESTION: I'd want to ask you all a big favour: If you've got a defective set (it should be a complete set of drained original or replacement batteries), I'd be very happy if you could send it to me. I'd pay the postal service, if you're not sure about (should be in Europe, otherwise it would be too expensive). If you send batteries , they should be in optically ok condition. What this is for: I want to do some tests with single batteries and battery sets regarding their charge/discharge behaviour under varying conditions. Also I'd like to do some tests on overcharging with different currents and total drainage. That would be very expensive, if I bought new batteries for this, as you might guess :) It hope, that this text has at least been usefull for some people who wonder about the miracles of battery cycles. If you want to help me, just drop me a message. Thank you very much in advance, Andreas Zwirtes Bradley Alexander schrieb: >On Wed, 2002-10-16 at 15:28, Josh (Norm) Audette wrote: > > >><NORM> >> How old are your batteries? Also, do you use a charger when you're in >> >> > >The batteries came with the unit, >1 yr old. I bought it secondhand from >a coworker, and she said that she had never used the second set of >batteries (which are in there now). I used to use a car charger, but do >not at present. (it was a cheap charger, and died on me.) > > > >> the car? Rechargeable batteries alter their charge/discharge cycle >> when you don't charge and discharge them fully. If you get into your >> car and plug in the charger whenever you drive, you'll start to alter >> your batteries' discharge characteristics. You can fix this by fully >> discharging and then charging it a few times. Also, have you tried >> running it on another set of batteries? >> >> > >This is the second (unused) set of batteries. > > > > Received on 2002-10-18 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |