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Old 07-06-07, 09:45 AM   #1
phantomcow2
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Dead laptop battery?

I am 99% sure that I've got a dead laptop battery here, but I thought I'd post the symptoms here in hopes of some confirmation.
Basically, I am getting no longevity out of them. I'll charge them up to 100%, and switch to battery power. It will say "2 hours remaining" or something close to that. It will fairly quickly (over the course of 10-15 minutes) drop to 84% life. It should still be good for a while at 84% though, but it shouldn't decline 16% in 10-15 minutes. Then, for seemingly no reason at all, it will fall to 11%. It won't even go through everything in between, it'll just go to 11% immediately. Then I get "Low battery warning". This battery is probably almost 4 years old, and I am pretty sure it's culpable here. Is there anything else that might be causing this? Especially the rapid drop in remaining charge?
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Old 07-06-07, 09:50 AM   #2
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You have a bad battery.

Happened to The Woman's Powerbook G4 a month ago. I would always remind her that leaving the damn thing plugged in 24/7 would ruin it. Cypress = Win
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Old 07-06-07, 09:54 AM   #3
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So leaving it in all the time is BAD for it?! Damn, lol. I got this thing used last August, and it still managed to get 1.5 hours off a charge. I leave laptop plugged into AC all the time, while using it or not. The little green light goes on and tells me that I am fully charged. I always thought I was trickle charging it from there. Maybe I am the primary cause of my batteries moribund state .
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Old 07-06-07, 10:56 AM   #4
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Batteries DO wear out! The older NiCad batteries CANNOT be left on charging all the time, they'll only discharged to their previous state. So if you plug it in when it's only 50% discharged, the next time, it'll only discharge to 50% and stop (you've cut run-time in half). On those, you MUST discharge them completely before plugging them back into the charger.

Newer NiMH and LiON batteries don't have that kind of memory and comes with a smart recharging circuit that prevents overcharging. Even then, there have been some big blunders. Case in point are the Sony batteries used on the Dell laptops that caught on fire due to using LiON batteries with a NiMH charging circuit. The voltage to charge-state curve may be very similar, but are not the same.

Most laptop batteries use 18650 cells. I just buy replacement cells on ebay and disassemble the battery-pack and solder in the new cells.
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Old 07-06-07, 10:57 AM   #5
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So leaving it in all the time is BAD for it?! Damn, lol. I got this thing used last August, and it still managed to get 1.5 hours off a charge. I leave laptop plugged into AC all the time, while using it or not. The little green light goes on and tells me that I am fully charged. I always thought I was trickle charging it from there. Maybe I am the primary cause of my batteries moribund state .

recharageable batteries have a tendency to develop a "memory". if they're used to receiving AC power constantly, they get used to not needing to use their full capacity and will begin to lose that capacity. i'm as guilty as you, though. when i first got my laptop, i'd get a few hours or so out of a battery charge. now, i'm lucky to get 10 or 15 minutes. i've got a spare battery somewhere, but it's still packed away in all the crap i brought home from baghdad. and i'm too lazy to go find it... so i deal. my laptop just lives plugged in.


in the future, the best way i know of to avoid this again is to not leave the laptop plugged in while the battery is installed. either a) take the battery out once it's charged or b) let it run on the battery every now and again to use up the whole charge. plug it back in, recharge and go again. it doesn't need to always run on the battery, but let it cycle once in a while.

YMMV.
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Old 07-06-07, 09:07 PM   #6
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Interesting. Well, this is a Li-Ion battery pack, made by gateway. I paid 60 bucks for a brand new battery with more capacity than my original, so that isn't too bad. I think I'll just take it out when I am on AC power and the battery is charged fully.
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Old 07-06-07, 09:17 PM   #7
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When you get it out of the box, kill it, then fully cycle it at least 2 times.


Try not to ruin it this time!
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Old 07-06-07, 11:18 PM   #8
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I thought that you could leave lithium ion battery packs plugged in all the time. The lithium batteries for my digital camera can be left in the charger without harm or loss of capacity. Are the laptop lithium cells different?
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Old 07-06-07, 11:38 PM   #9
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In any case, for some reason battery packs, no matter if they are NiCad, LiIon, or whatnot die after 3 years regardless of charging habits or use. Most places warranty batteries for a year, maximum. It does help, if your laptop has a recalibrate battery function, to run that every couple months, and you can usually see the battery losing charge capacity over time. Ironically, the batteries I have that still hold a charge after almost a decade are some lithium ion AA batteries which I use to power a couple digital cameras.

If its a "mission critical" appliance like a UPS, I'd consider a preventative battery yank yearly.
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Old 07-07-07, 05:18 AM   #10
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DON'T BUY GENERIC BATTER PACKS.

Do what Danno does....fix a manufacturer pack. The charging circuits are far better designed, so you are far less likely to have problems from it (I've seen a bad charging circuit cause a small battery fire), and you are sure to have hte right voltage design (one generic I bought for my LS was putting out 4V too much, which will actually cause accelrated wear on the systemboard....that's bad, batteries are easier to find than that specific systemboard version, far cheaper too).
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Old 07-07-07, 05:29 AM   #11
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You know, rebuilding this pack doesn't sound like a bad idea. I think I'll go ahead and try it, and call it a spare.
So when all is said and done, what is the ideal habit to extend the life of htis Li-Ion battery pack? Is it periodic full charges and discharges? Half discharges and then fully charge?
I do not believe that my laptop will overcharge the battery. The LED glows orange while the battery is being charged, and green while it is fully charged. It might trickle, I don't know.
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Old 07-07-07, 05:33 AM   #12
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Best bet is to never let the battery heavily discharge. Once a Li-Ion cell goes to 0, it cannot be recharged.

Also keep in mind Li-Ion bateries destroy themselves through usage....there is a current limit that once it's been delivered, that's it...no more battery. And they also have a high decay rate, so the batteries do die off after a few years regardless of use.

Basically, batteries will die, it's just a fact of life....to maximize laptop battery life, just don't use the battery all the time. It can stay in the laptop, you just shouldn't use the laptop wirelessly just because you can. Only do it when you need to.
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Old 07-07-07, 05:35 AM   #13
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Go to battery station, they have all the generic cells you need.

I don't know about cypress but i've kept my mobile workstation plugged in for like, the past 2 years, taking it off line voltage for 2-3 days a week with the battery just left in it and it still works like new. All lithium packs have a protection circuit inside to prevent deep discharge pass a certain voltage.
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Old 07-07-07, 05:36 AM   #14
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Danno, how many of those batteries do you typically use to replace a battery pack's internals? My laptop battery is 14.8v output, and 4400mAh capacity. So, if I am right, that means I would need 8 of those things. I guess I'll take apart my original to be sure of what it is.
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Old 07-07-07, 05:37 AM   #15
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True, but the problem is often that those batteries have a high discharge rate when unplugged and not used (about 1% a day), so if it's not plugged in within two weeks, you can 0 out a cell.


PC2, just test the cells out...charge it to "full", then read out each individual cell....the one that reads far lwoer is the bad one. Replace just that one cell and all should be fine for a while.

If you want to be picky replace any that are a certain percentage below nominal specs.
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Old 07-07-07, 09:57 AM   #16
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Quote:
Originally Posted by Cypress
You have a bad battery.

Happened to The Woman's Powerbook G4 a month ago. I would always remind her that leaving the damn thing plugged in 24/7 would ruin it. Cypress = Win
As far as i know most new computers come with a sort of overcharge protection.
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Old 07-07-07, 10:11 AM   #17
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Quote:
Originally Posted by phantomcow2
Danno, how many of those batteries do you typically use to replace a battery pack's internals? My laptop battery is 14.8v output, and 4400mAh capacity. So, if I am right, that means I would need 8 of those things. I guess I'll take apart my original to be sure of what it is.
You need at minimum 4 for the proper voltage (4x3.6=14.4v). On my Dell, it had an 8-cell battery using two sets of 4x3.6v to double capacity. So individual cells were 1600mah arranged 4 in serial for a 14.4v 1600ma battery and this pack was set up in parallel with a second set of 4 to double capacity to 3200ma. I replaced all the cells with 2200ma Panasonic batteries to get 50% more runtime.
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Old 07-07-07, 01:00 PM   #18
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So I checked inside that dead pack. It looks like they are using 8 of the 18650 cells, all neatly arranged. I think each cell is 1800mAh, giving me the 3600 network. Looks like all the ones around are 2200, which is why the new battery pack I got is 4400mAh. I'll give this a go
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Old 07-07-07, 01:18 PM   #19
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Not to belabor this, but it has been quite a while since NiCad batteries have had a
memory problem. We have used them for uears in the TV industry and I can't remember memory problems for the past 4-5 years.

We have never had memory problems with NiMH (Nickel Metal Hydride), but they are limited to three years or about 200 charge/discharge cycles.

Our cross town rivals use LiOn and have yet to have any memory problems, but again are only getting about 200 charge/discharge cycles.

And no, Hydrogen fuel cells are not the answer. What a pain in the buttt. And when the Hydrogen alarm goes off......we vacate the building.

Lastly, I admit I am talking about camera batteries, not laptop batteries, but at about $600 each we are not talking cheap batteries.
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Old 07-07-07, 01:36 PM   #20
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I wish the chatter about batteries like the capacitor battery that is jabbered about on slashdot and other places would actually get into production. Then, you just plug in whatever gizmo you have for 5-10 seconds, and you have a full charge for the rest of the day or week, or whatever. Since its a capacitor, it doesn't lose charge over time and need replacing so often.

Reference: http://peswiki.com/index.php/Directo...uper_Capacitor
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