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Laptop Battery Saving Strategy
Old 07-04-2008, 08:19 AM   #1
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Laptop Battery Saving Strategy

The Li-ion battery on my 1.5-year-old Dell laptop can hold a charge for 14 minutes. This deterioration is most likely due to the thigh-frying temperature that my laptop runs at.
At a 100% charge level, a typical Li-ion laptop battery that is full most of the time at 25 degrees Celsius or 77 degrees Fahrenheit will irreversibly lose approximately 20% capacity per year. However, a battery stored inside a poorly ventilated laptop may be subject to a prolonged exposure to much higher temperatures than 25 C, which will significantly shorten its life. The capacity loss begins from the time the battery was manufactured, and occurs even when the battery is unused. Different storage temperatures produce different loss results: 6% loss at 0 C (32 F), 20% at 25 C (77 F), and 35% at 40 C (104 F). When stored at 40% - 60% charge level, these figures are reduced to 2%, 4%, 15% at 0, 25 and 40 degrees Celsius respectively.

So I was thinking that to reduce the deterioration of the battery in DW's new laptop, which she always uses on AC power, I'd take out her battery and store it in the fridge. That is, she'll use the laptop without the battery in it.

I guess the main disadvantage is that if the power goes out,
she could lose her work.

Thoughts?
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Old 07-04-2008, 08:38 AM   #2
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I wasn't aware that a laptop could be run on A/C without the battery in it, due to the circuitry!!

But then, what do I know.
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Old 07-04-2008, 09:10 AM   #3
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Yep that'll work Al. Most laptops will run fine with their battery out and even with a removable drive bay cd/dvd/floppy drive removed.

A little bumpier on the bottom.

You could also use a USB powered laptop coolerpad, or go the route I went. A 50c flat cookie sheet a little larger than the laptop. Prevents blocking of the air vents on the bottom, gives a little space, and the cookie sheet absorbs and heatsinks all the excess heat away.
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Old 07-04-2008, 10:04 AM   #4
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T-AL, maybe you should investigate the 'thigh-frying' temperatures - are they typical for that model/usage?

My daughter recently told me that her laptop fan seemed to be running more than usual, and that the battery didn't last as long. I looked, and one of the cores was running at 100% while everything was just idle. I traced it down to something 'stuck' in the printer queue that was trying to print to some network printer that it no longer had access to. I killed the print job, and I could hear the fans slow down in just a few seconds. All better.

My sons 3 YO battery seems to be fine (the laptop is 4 YO, the first battery was part of a recall/replace). I don't know what is typical, but 1.5 yrs seems short, but maybe you got a marginal one.

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Old 07-04-2008, 12:15 PM   #5
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My IBook battery deteriorated rapidly so I went on Ebay and bought a new one for only $50. Works great. Before spending alot of effort on fixes, you might consider a new battery.
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Old 07-04-2008, 12:52 PM   #6
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My IBook battery deteriorated rapidly so I went on Ebay and bought a new one for only $50. Works great. Before spending alot of effort on fixes, you might consider a new battery.
Except, if he does have a run-away process that is sucking up CPU cycles, a new battery won't 'fix' anything. It's pretty simple to look into the Activity Monitor (or whatever the Windows equiv. is called these days) and see if things look OK. At idle, there should not be a lot of activity.

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Old 07-04-2008, 06:09 PM   #7
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Al,
....You do know about lithium batteries in laptops blowing up occasionally? Over on CandlePower forums (yes, 10000 flashlight maniacs have a website) there are lots of people using rechargeable lithiums and "lithium cells venting with flames" gets posted fairly often. Typically failures are temperature and sometimes condensation related. I would be careful going in an out of refrigerator with the possibility of condensation leading to corrosion and lithium cell case degradation. I have rechargeable 123 size lithium ion cells and take them to the recycling place first time they do not charge and last up to par.
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Old 07-04-2008, 06:22 PM   #8
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DW put the kibosh on anyway, saying that she sometimes needs to take the computer upstairs to print something.

Quote:
yes, 10000 flashlight maniacs have a website
Wow.
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Old 07-04-2008, 06:56 PM   #9
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yes, 10000 Flashlight Maniacs Have A Website
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wow.
10,001?
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Old 07-05-2008, 12:47 AM   #10
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10,001?
I used to spend too much time reading and posting there. I finally realized that I have several lifetimes worth of flashlights and stopped getting any more of them. It actually is a pretty good website. Mostly young folks and very international. Many of them are electronics and gadget nuts and they come up with some pretty cool "science projects".
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Old 07-05-2008, 12:59 AM   #11
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The best way to store them is at low temperature and low state of charge.

The is usually inconvenient for computers and phones but may help for things like camcorders.

I suggest discharging it completely in what ever device you are using it for (the electronics should prevent over discharge) and then charging it for maybe five minutes before putting it in the freezer.

Allow enough time to first allow it to warm up before charging because some cells are sensitive cold charging.

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Old 07-05-2008, 10:00 AM   #12
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Here ya go Al. $5 after rebate.

FRYS.com*|*Antec
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Old 07-05-2008, 12:14 PM   #13
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I think I've got that exact Antec cooler and it works very well.
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Old 07-05-2008, 02:24 PM   #14
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The best way to store them is at low temperature and low state of charge.

The is usually inconvenient for computers and phones but may help for things like camcorders.

I suggest discharging it completely in what ever device you are using it for (the electronics should prevent over discharge) and then charging it for maybe five minutes before putting it in the freezer.

Allow enough time to first allow it to warm up before charging because some cells are sensitive cold charging.

MB
MB,
....Your storage recommendations may be right for other batteries but they are wrong for Lithium batteries. Have a look at
How to prolong lithium-based batteries
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Old 07-05-2008, 03:20 PM   #15
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MB,
....Your storage recommendations may be right for other batteries but they are wrong for Lithium batteries. Have a look at
How to prolong lithium-based batteries
jclarksnakes,

I have looked at this site before but only scanned it this time. As far as I can tell he basically agrees with me. This is the key point from BatteryUniversity.com:

Quote:
Figure 1: Permanent capacity loss of lithium-ion as a function of temperature and charge level.
High charge levels and elevated temperatures hasten permanent capacity loss. Improvements in chemistry have increased the storage performance of lithium-ion batteries.



Is there a specific discrepancy between what I said and what is on the web site that I misssed?

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Old 07-06-2008, 12:58 AM   #16
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mb,
..The website says to not freeze them but to instead put them in the refirgerator. The website also says to store them at 40% of charge. The five minutes of charging from complete discharge you mentioned would probably not bring them up to 40% of charge though admittedly it might..
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Old 07-06-2008, 04:35 PM   #17
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mb,
..The website says to not freeze them but to instead put them in the refirgerator. The website also says to store them at 40% of charge. The five minutes of charging from complete discharge you mentioned would probably not bring them up to 40% of charge though admittedly it might..
Jeff
OK thanks I didn't read it very closely. Thanks for pointing this out.

I'll make a couple of comments at the risk of giving you more detail than you really want.

His recommendations are a bit more conservative. I don't think the differences are that significant. His recommendations are fine. Mine are more aggressive but they should also be ok.

As a bit of background about myself I have a Ph.D. in chemical engineering and have experience in battery, fuel cell and supercapacitor R/D including Li-ion.

You are correct, 5 minutes will not get them up to 40% state of charge. The risk of very low state of charge (<<<40%) is that the self discharge will decrease the voltage to the point that the negative electrode current collector corrodes. This will destroy the battery. But the true self discharge in these batteries is very low and it is even lower at low temp and low state of charge. I have stored batteries with cells similar to those in your laptop or cell phone at essentially 0% state of charge and a temperature of 0C with no recharge since 2000 and they are fine.

The issue with freezing them is if it gets cold enough to freeze the electrolye or if the seal leaks at low temperature. The electrolyte freezes at between -20C and -40C depending on which particular blend of solvents are used. I'm not aware of any electrolyte that freezes above -20C. Also I would be very surprised if there are any commencial cells out there that are not designed to tolerate temperatures of 0C for storage.

So follow Mr Buchmann's recommendations and you will be fine and they will last longer than if you stored them fully charged at room temperature. Follow my recommendations and they may last a bit longer than for Mr. Buchmann's recommendations but to tell the truth you will probably not notice the difference. But perhaps like the attorneys and FAs I should add that you follow my advice at your own risk

MB
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Old 07-06-2008, 11:25 PM   #18
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MB,
....Thanks for the info. I am thinking that over the next few years there will be lots of people learning about lithium ion battery technology. You mention super capacitor and Lithium Ion R&D pretty close together there? As in super capacitors in combination with lithium ion cells for automobile power applications?
Jeff
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