Li-Ion Laptop Battery Question

[JSWrightOC]

For those of you here who are familiar with Lithium Ion chemistry batteries, I have a question about the performance of mine.

Recently, my laptop battery began not taking a charge beyond 63%. That is, the charging indicator on the computer would go out, but the battery meter in Windows would show 63% and not go any higher.

Deep cycling the battery brought capacity back (both in percentage and actual runtime) a few percent at a time and I now have it up to 76%. What could possibly cause this, how can I condition the battery, and, most importantly...how can I keep it from happening again?

Thanks for any input!!

 

[NCBirdHunter]

Hello fellow Charlottean...

How old is the battery? If you've had it for a couple of years, it may just be reaching the end of its useful life. For a great website -- with tons of helpful info regarding batteries -- check out Batteries in a Portable World. For a discussion specific to Li Ion batteries, go to this page.

As I'm sure you are aware, Li Ion batteries do not have the 'memory effect' made famous by NiCads, but they DO have a useful life (typically measured in the number of charge/discharge cycles -- even though the battery may never actually get fully discharged).

I have had my Toshiba Portege for about two years and the battery has pretty much lost its useful life -- it will only last about 30 minutes on a full charge. (On a side note, I work for one of the 'big banks' here and our IT group will charge my cost center $400 to replace my old battery with new one -- even though I can order one online for less than $100, but company policy prohibits it!! And we think the government is bureaucratic!).

OzMan

 

[stevendao]

http://www.bealecorner.com/trv900/lithium.html
I found this site showing how to restore a dead Infolithium battery for Sony camcorder. It may be applied to the laptop computer since both use the same individual cell (18650) inside the pack.
I already tried with my sony battery and it works.
Steven D.

 

[JSWrightOC]

Thanks for the help, guys.

OzMan,

The battery is about 1.5 years old, and has seen moderate use--nothing very heavy. Even though the runtime is less than what it should be, I can still get an hour and a half out of it easily.

That's sad, about the battery purchase. I say get a replacement and just don't tell anyone! /ubbthreads/images/graemlins/wink.gif However, I guess that depends if you think it's worth $100 of your personal money or not.

After reading the link stevendao posted, you might want to try that as an option!

stevendao,

Wow! That's an interesting story. I might have to rig a discharge resistor to the pack and try that out. I am almost certain the pack has overdischarge protection (what Li-Ion packs don't these days?) so it might be an experiment worth trying, at least once.

I have an old Sony Digital Mavica that came with an NP-F330 battery, and I also purchased an NP-F550 pack for it--both seem to be working fine. If I ever have any problems with them, however, I'll know what to do. /ubbthreads/images/graemlins/smile.gif

You are probably right, most likely two 1800~1850mAh cells in parallel x 4, to reach the stated 14.4V and 3600mAh. The pack is a model BTP-34A1, but that is the only real identifying information on it (the rest of the printed information consists of cautionary statements in three languages). Cells made in Japan, assembled in Taiwan. The laptop is an Acer TravelMate TM529TXV...and I think Acer stopped selling replacements. /ubbthreads/images/graemlins/frown.gif

 

[Floating Spots]

[ QUOTE ]
JSWrightOC said:

That is, the charging indicator on the computer would go out, but the battery meter in Windows would show 63% and not go any higher.


[/ QUOTE ]

By deep cycling, are you letting the computer go to the point it shuts itself down?
Windows used to require that you run the battery completely dead (til the computer shuts off). Recharge it all the way and do it again. That used to calibrate Windows to the actual battery level. Maybe that is what you have already done?

 

[BF Hammer]

The Li Ion battery in my Sony computer started giving shorter run time cycles when it was about 1.5 years old, and it gave out entirely this last March after just under 2.5 years service. All it did at the end was get very hot (internal short) while charging. I did take notice that the internal shorting happened to a small degree a couple of days after flying to another city (computer was X-rayed at security checkpoint) and became so bad as to be unusable with battery power the day after flying home (again through the X-ray machine). I've never read any information about X-rays affecting Li Ion batteries, but I have my suspicions now - especially if the battery is getting weak.

 

[James S]

LiIon batts definitely have a useful life and they drop off VERY quickly at the end of that. 1.5 to 2 years is very good life. Longer depending on usage but much more you will not get.

The rundown thing doesn't calibrate windows, and it doesn't bring any real capacity back to the battery it calibrates the chip in the smart battery packs. You can't get a percent left kind of reading on a LiIon pack by watching battery voltage or anything like that. There is a chip in there that actually measures the amount of power that goes in and out of the pack. When you run it all the way down that chip starts counting from zero again on the next charge cycle. So it knows how much energy is actually in there and can report it to windows or MacOS or whatever. (you didn't ever wonder why your battery pack has so many more connections than just +&-? One of them is a serial line!)

It is possible that the power manager part of the computer will stop the charge when the chip thinks it's absorbed 100% of the rated power rather than continue to charge beyond that. So if the number is off it may not be getting fully charged by the laptop.

There was some talk on some Mac trouble shooting boards recently that shorting out the pack for a fraction of a second would reset this. The reason that this may also help is that once you short it the packs over discharge circuit kicks in and basically cuts the power completely from the pack. Resetting the charge sensor in the process. But this is dangerous! These things put out a lot of current, and if there happens to be something wrong with that protection circuit those cells can catch fire and explode in not too many more seconds. So this particular technique is not for the feint of heart!

My own batteries are starting to show their age. I wish I could get some more of these:

anybody know a source that will sell me them? They want $130 for a new pack and thats just WAY too much.

 

[JSWrightOC]

By deep cycling, I mean operating the computer until the over-discharge protection circuitry disconnects the output. If I boot the comptuer and enter BIOS setup, power management does not apply; the current drawn by the LCD, hard drive, and the little bit by the processor (which is mostly idle at this point) sip away at the battery until it is absolutely dead. After I perform this operation and it shuts off, the computer will not even turn on.

Yes, the percent charge remaining indication is derived from a battery controller chip inside the pack, not Windows. Since I was gaining both percentage *and* actual runtime (it lasted a longer period of time) I am led to believe that I actually was conditioning the cells. The links posted by OzMan and stevendao proved to be quite useful. Thanks again, guys! As for the actual lifespan (in years) of the pack, that depends a lot on what kind of temperatures you store, charge, and operate it in. Higher temps equals shorter life. When storing them, I knew there had to be a reason why Dell (maker of my old old laptop) said that you should store the batteries mostly (but not completely) dead (<40%).

James S:

Those cells look just like the ones in an old laptop battery that I tore apart once. For all I know they are all the same. Have lots of fun finding replacements, because I don't think you can get them anywhere except straight from the manufacturer, and then you better have a contract with them, signed waivers, etc. It boils down to the manufacturer doesn't want to sell the end user a bare battery, even though we may know a lot more about safety precuations than the average consumer. To them however, we are all the same.

$140 sounds right, that's about what you would pay for anybody's 14.4V 3600mAh Li-Ion pack. Either way it's still a ripoff though.

 

[FalconFX]

James, those look like 18650 Li-Ions... Are they? If they are, I think you can order the cells directly from either Panasonic, Sony, Sanyo or places like onlybatteries.com...

 

[paulr]

Those look like the cells in the Ultra-extended Nokia 51xx cellular phone packs that various dealers are selling for $10 or so on ebay (they have two cells inside). You can also get them from www.newegg.com for $10.99:

http://www.newegg.com/app/viewproduct.asp?description=75-201-007&DEPA=2

 

[Blikbok]

There are two things at work in a laptop battery pack, the Li-Ion cells, and the "Smart" circuitry. Cycling the battery may recalibrate the smart circuitry, especially if the battery was always used for shallow discharges. But cycling the battery won't resuccitate the cells themselves. They age irrepairably over time.

You don't have to completely kill the battery to recalibrate the smarts in it. Just unplug the laptop from the wall and use it until it shuts off. Charge the battery with the laptop off until it claims to be full, and then start the laptop again.

What the computer says about the charge might be true. I don't know how your charge indicator works. It may be counting actual current in and out. But if the battery itself is giving you about 50% of it's original capacity, look into replacing it.