How to make sure your laptop battery lasts long

[Too Smart]

Here is some information about laptop batteries I have compiled over time after searching a lot about it on the internet. This information applies only to lithium ion batteries. Pretty much every laptop being built these days uses this type of battery.

1) Li-ion batteries have a life of about 400-500 recharge cycles, or about 3 years, whichever comes first. After that, they don't work at all, or too poorly to be of any use.

2) People who have been using laptops since the days of NiCd batteries are used to having to fully discharge their batteries before charging them. You should not do this with Li-ion batteries, this will actually reduce their life. However, you should still discharge them fully every 50 charge cycles or so, otherwise the battery may not report the correct amount of charge remaining in it.

3) The number one killer of Li-ion batteries is heat. Storing batteries in hot places (like a car in the summer) for long periods of time will reduce their life. Also, if you're using your laptop on AC power and the battery is fully charged, it is better to take the battery out of the laptop than leave it in, due to the heat. But do not let dirt or dust or whatever get in the laptop where the battery goes.

4) If a Li-ion battery will not be used for a long time, it is best to store it with 30-40% charge remaining. Then when you need to use it again, charge it fully before using. Also, store it somewhere where it's cool. One website even recommended storing it in your fridge (but not the freezer).

5) Although it should take about 3 hours to fully charge a laptop battery, the majority of the charging happens in the first hour. You might notice your battery charges up to about 90% pretty quickly, but then it takes a really long time to charge that remaining 5 or 10%. It is not harmful to the battery to not charge it all the way to 100% every time if you don't want to (although when it's new, you should charge it to 100% the first 3 or 4 times to break it in).

There is no standardization of laptop batteries, so once a battery dies, you will have a difficult time finding a replacement because a battery from one laptop brand will not fit into another laptop. So your only source of a replacement is your manufacturer, however by the time your laptop battery is old enough to not work, your manufacturer will probably have stopped manufacturing the type of battery you need a long time ago, and even if they have some batteries remaining to sell you, the batteries will not last as long as new batteries because Li-ion batteries only work for about 3 years after they are built. For this reason, some people are pushing for a standardization of laptop batteries, ie for all laptop manufacturers to design batteries of the same size and shape so that one will fit all. Here is an interesting petition which describes this in detail which I really recommend to be read by anyone interested in this: http://www.hanno.de/laptop-petition/

[Albuquerque]

I find that a brand new Li-Ion battery needs about three full charge / full drain cycles to properly report it's true full capacity. Case in point: Brand new 4000mAh battery I purchased online for my TP600E. When I first got it fully charged, it's rated capacity and total capcity were both ~4300mah. After a complete drain (Prime95 in torture mode, turned all power management features off) and then a complete charge again, the total charge capacity hopped to ~4700mAh. One more cycle of the same, and the total charge capacity is now just a scant few milliamphours shy of 4900.

I use a utility called MobileMeter to view the battery's charge status.

[Icedfire101]

I have also noticed with my own laptop that if i only let it disharge higher then 85% and then try to charge i sometimes doesn't want to go all the way back to 100% untill i discharge it past 85% again... a rule for me is to always drain my battery past 85%...

[ozzlo]

the only things I can think of to help prolong your battery are

keep it cool (probbably the best thing for your battery)

don't burn cd's while on battery power (even though You could it puts major major load on battery)
dont drop it
when not using it store it at 30-50% charge
even though it's stated that you don't have to i still like to give it a full discharge at least once a week...

[Flamingtaco]

I've seen some aftermarket battery suppliers; they may make replacements for older batteries.

When purchasing a replacement rechargeable battery, ALWAYS check the MFG date on it! If it's older than 2-3 months, I'll take them back. You shouldn't see them older than 4-5 months, though. The mfgs and distributors know their is a short shelf life, and they try to avoid overproduction.

While the battery pack (batteries inside a purty case) as a whole is not standardized, if you peel off the plastic label that contains all the info printed on the battery pack, or crack open the case, you will find that inside the cells are standardized primary cells. You can go to places like Batteries Plus, and they will rebuild packs for you, although the cost might not warrant it, it just depends on the outlet. For those that are slightly electrically inclined, you can order the cells yourself and rebuild the pack.

On a slight tangent, Li-on cells have a "problem" that can be fixed most times. The anode or cathode, I forget, developes a resistance due to the deposition of material at the junction. This deposit develops anytime the battery is sitting at room temperature and not being used. Fortunately, charging and discharging the battery removes these deposits. UNFORTUNATELY, electronic devices exaggerate the problem because they tend to shut down when the voltage reaches a certain level, preventing you from deep-discharging the Li-on cells.

This is NOT to be confused with the neccesity to deep-discharge Ni-cad batteries! Li-on cells do not need constant deep-discharges to retain their capacity. However, performing a few deep-discharge/recharge cycles every six months has proven to extend the life of Li-on batteries, and performing multiple deep discharge/recharge cycles can bring "dead" Li-on batteries back to life.

The key to this is to actually getting the batteries deep-discharged. With a single cell, it is as simple as connecting a 10W resistor or a light bulb to the battery and letting it drain to 10% capacity or less. You camera or laptop will not let you do this. Some battery packs will shut down the juice if voltage drops to a certain point, so you may have to discombobulate the pack to get it done.

Another note: I've opened many battery packs to find one or two out of 6-12 batteries actually dead, and causing all the trouble. Replace just those batteries, and voila! The pack is back! ;)

A last note: Heat kills batteries, so if you are using the computer on the plug (power) for extended periods, take the battery out! If you plan on having the battery out for extended periods (months on end), discharge it below 50%, then place it in the refrigerator. NOT THE FREEZER.

Attached (hopefully) is an image of the inside of the pack from my HP N5420L. I took it apart just so I could show you what I am talking about. I immediately noted something very disturbing upon opening the pack... HP shorted me 33% of possible power! The batteries are arranged in a 2x3 formation... three series of two batteries in parallel... it looks like this:

-☻- -☻- -☻-
| | | |
-☻- -☻- -☻-

Imagine all the lines are actually connected together...

Now, if you look at the batteries, you will notice there are three plastic cylinders mixed in with them. These cylinders are EXACTLY the size of the batteries that were used, and if one were to replace them with actual cells, you would end up with the same voltage, except in a 3x3 configuration, adding another 1800mAH to the battery! How lame! The battery could be 5400mAH instead of 3600, and give my laptop 30% more life! What a bunch of cheap-butts!

So, It seems my third laptop project will be rebuilding the pack. Not only will I add the three extra cells, but I am also going to seek out higher capacity cells. I believe I've seen 2400mAH cells in that size. A 7200mAH battery for the laptop would rock. I built a pack for my video camera, which came with a 4" LCD screen, no view finder, and a cheesy-as-can-be 2800mAH battery that fits INSIDE the camera (can't use oversize batteries). I purchased 6 8,000mAH C-cell NiMH's and built a pack for it. I spliced a connector onto the A/C adaptor (the connector for the camera looks like a battery and goes in the battery cage!) and voila! I've got a 16,000mAH battery pack that runs the camera all day long, literally.

On a last tangent note, back in the day (1991), I bought a brand-new Sony portable CD-player. It came with a battery pack that attached to the bottom of the player, and was the entire width and breadth of the unit. If the laptop companies standardize the batteries (Oh, please, please, start using NiMH C or D-cells, please!!!), or at least the connectors, companies can make mega battery packs that will run the laptops for several days straight. What is surprising, is that someone is not already making them. You could make a pack that has an A/C inverter that plugs into the A/C plug on the laptop. Seems someone would have jumped on this by now, as long as people have been complaining about short battery life on these laptops. Yes, these packs would be very heavy. I've been toying with the idea of making one. There's a perfect place in my laptop's case for a big pack, and room for 5-10' of cord.

Just some thoughts...

[Too Smart]

You could make a pack that has an A/C inverter that plugs into the A/C plug on the laptop.
Yeah that's a good idea, you'd think someone would have designed that by now, I'm sure they'd be hot sellers. Although I think they wouldn't be quite as convenient as the standard battery which plugs neatly into the laptop so you don't have to carry anything externally. But if such a device could be built, it shouldn't have to be any larger or heavier than a laptop battery, right? Then it would have a wire going from itself to the AC plug.

[ozzlo]

^^^^ they do allready.... you buy this battery for $120 and then you get an adapter tip that has the right resistance to supply the correct voltage for your laptop I seen em at best buy. it plugs straight into the adapter port and can make a p4 last an extra 2-3 hours... load

[Too Smart]

Really, I had never seen that before. I'm gonna look for it next time I'm at Best Buy.

[Sjaak]

Good stuff to read, but most should be common knowledge for users who work with mobile stuff :)

I just got a replacement a week ago for my dying Laptop battery (after about three years). Its a 4400mAh NiMh Cell.

Bad thing is i move my laptop around alot..so i cannot afford to unplug the accu everytime i have it on the net charger. Well, in three years i'll have a new laptop anyway.

[Albuquerque]

You guys talking about the high capacity laptop batteries that plug into the AC port might want to look into Electrovaya's PowerPad offerings that come in 80Wh (http://www.electrovaya.com/product/powerpad80.html), 120Wh (http://www.electrovaya.com/product/powerpad120.html) or the 160Wh (http://www.electrovaya.com/product/powerpad160.html) flavors. These are lightweight Lithium Polymer pads that have taken quite a beating from our international travellers at my office. We have a good handful of the PowerPad 120's and 160's. With one of the 160's, I've had my Thinkpad R50 powered for as much as twelve hours...

[Icedfire101]

ya i have read alot of about the powerpads, the only downside to them is that you should take your battary pack out when using it (as it will try and charge the battary and run your computer at the same time which will decrease battary power in the powerpad) and you can't really tell how much is left in the powerpad (yes there is a little strip of leds, but for that kinda money i would think putting a usb cable on it to report the remaining battery level would have been to hard)

[ps2cho]

thats some interesting information that applies to all laptops.
this should be made a sticky imo.

[Foxie3a]

Wow, a good read. Not something you come across everyday.

What is the difference between the Li-ion and the Ni-mh(I think that's what the second is called, or atleast something similar)?

I'm starting to use my laptop more and more, and when I'm thinking is that we don't need better batteries, we need better power sources.

I know the technology just isn't here yet for mainstream use, but maybe recharging the battery through solar panels which are on the lid of the laptop. Or maybe something that converts heat to power. It'd be nice to take all of the heat from my laptop and convert it into power. Maybe someday. But for now I'm stuck with my 20 minute long battery.

Oh, and I agree about CD's. They BURN through my battery like crazy. Don't they spin at like 10K RPM? My 40gb in my laptop takes 0.8a on the 5v rail, and I was looking at a DVD drive similar to mine in the laptop that was 2a on the 12v rail!

[Sjaak]

What is the difference between the Li-ion and the Ni-mh(I think that's what the second is called, or atleast something similar)?


The Li-Ion batteries are newer (the used to be more expensive but that has dropped now), and they don't suffer from the 'memory effect' as bad as NiCD batteries. NiMH is somewhere in between of them.

[Dylruss]

It is a good read and something mobile users should know, if they don't already.

I know that keeping them charged is the best way to let them last longer.

[Slimmy]

Nice info! I just bought a lappy. So this will help alot. Thanks.

[Albuquerque]

ya i have read alot of about the powerpads, the only downside to them is that you should take your battary pack out when using it (as it will try and charge the battary and run your computer at the same time which will decrease battary power in the powerpad)
Nonsense. They specifically TELL you to leave your battery in. Your battery will not "try to charge" unless it isn't fully charged anyway. For obvious maximum power opportunities, you should have your onboard battery charged and use the powerpad first and then begin draining your onboard battery next.

and you can't really tell how much is left in the powerpad (yes there is a little strip of leds, but for that kinda money i would think putting a usb cable on it to report the remaining battery level would have been to hard)
Yeah, I can generally agree with this, but when used like it's supposed to, it doesn't really matter. If you see you're on the last red LED and then suddenly your laptop beeps, you know it died ;) Having used one probably four dozen times, I've never had it "surprise me" simply because it's always more than enough power anyway. The one time that I used it for twelve hours was during a road trip, and while I had a DC/AC inverter with me, I was just curious how far I could get it to go.

[Mr B]

thats some interesting information that applies to all laptops.
this should be made a sticky imo.

I've been toying off and on about doing just that with this thread...I think now I will. ;)

B.

[Pc geek]

Wow great thread!

[Flamingtaco]

NiMH are newer than Li-on batteries, at least market-wise. I'm not sure which type NASA came up with first, but I'm fairly certain that NiMH is their newer technology. I've got a camcorder built in '99 that takes Li-on. NiMH have "come onto the scene" within just the past 2-3 years.

Technically, neither Li-on nor NiMH have any "memory affects" like the NiCD batteries. When used properly and frequently, the Li-on's will not see capacity drop except for normal wear, and the NiMH's have no know capacity issues other than normal wear to date. Like I stated previously, though, you do need to do full drains on the Li-ons several times a year, and the electronic devices do not allow us to do this, so you need to do the resistor drain thing. The NiMH's have no need to deep-discharge, although doing so at first use does seem to improve their capacity.

I checked out the Electrovaya battery packs and WHOA! $550 for their smallest battery! That's nuts! Looks like they are going by the average, well over-charged rate we have to pay for the oem batteries. $100 will net you that same 80AH, but in NiMH D-cells. I could build an output regulator for about $20, $15 for a nice fiberglass case, and $10 for battery holders. $150 Vs $550... talk about disparity! Not to mention the fact that Electrovaya does not even have a unit for the HP's yet. I know some of us can afford that, but I think most people didn't pay much more than $550 for their laptop, and can't conceive of paying that much for a big battery. I don't have time right now, but maybe later this year I'll look into the feasability of producing battery packs. Considering what my cost would be, I could easily come in WAY under Electrovaya's price. $550 is just too much for 80AH.

LOL... I just though of something... I could provide long-life batteries right now for just $160!

Large car battery - $80
Your mfg's 12V adaptor - $30
High current 12V recharger - $50

Oh, wait, I need some profit... Get them now at the cheap price of just $299!!!

[four4875]

i felt compelled to rip opem my "14 cell" battery, so i did. suprised to find 8 cells, not 14. and the small circuit with the charge lights thing, it has a temp probe on it im gonan shap a few shots with the webcam. battery is to a compaq evo N115 aka presario 700, and fits a few others.

[four4875]

heres a shot of the temp probe lifted up

im guessing its so that the laptop can monitor the temp of the battery while charging, some pretty sophistcated stuff if ya ask me. i need to figure out the wiring setup (series parallel and all) and see if i can play around with ths

[Penel]

Good sticky! For XPS owners like myself, just carry a generator with you :D

[eXCeSS]

Good sticky! For XPS owners like myself, just carry a generator with you :D

LOL

Great info, thanks!

[Sjaak]

Good sticky! For XPS owners like myself, just carry a generator with you :D

Ive seen some Yamaha generators of about 600 VA (or more?) that would fit in a large bag...only the noise :p

[Flamingtaco]

heres a shot of the temp probe lifted up

im guessing its so that the laptop can monitor the temp of the battery while charging, some pretty sophistcated stuff if ya ask me. i need to figure out the wiring setup (series parallel and all) and see if i can play around with ths
The temp is monitored to determine the charge condition of the batteries. Batteries put out varying levels of heat, depending upon how much charge they are taking. You can also use it to determine that there are individual cells that are dying, and some mfg's use this to generate imminent failure warnings.

[TheGreySpectre]

Most laptops have an auto screen contrast/brightness drop when they shift into battery mode, leave this or even turn it down further if your on battery. On my 9300 the differcebetween max screen brightness/contrast and and min brightness/contrast is about 1hour 15 min

[Eric1285]

Great guide, I can't think of anything that wasn't mentioned in the thread already.

[Stoanhart]

How much does each of those cells produce, voltage wise? Is that standardized? If it is close to an AA battery, since that's what they look like, it would be neat to take the shell and interface of a dead battery, and make a sort of mounting system for 8 rechargable AA's.

Then buy an 8 battery charger and 16 batteries. Put 8 in while you charge the others, swap as necessary. Worth a shot... The battery is dead anyways. I guess you would have to be careful not to plug the AC in when you have the home made battery in, because I don't think the laptop's charger could properly handle the new battery.

[chrism131]

Great Thread, I really needed this information because I just bought a new battery. Thanks :)

[Cowboy X]

Here is some more info on the same sort of stuff :

http://www.mobilityguru.com/2005/11/02/squeezing_more_life_out_of_your_notebook/

or skip to the recommendations :

http://www.mobilityguru.com/2005/11/02/squeezing_more_life_out_of_your_notebook/page28.html

The first article is here :

http://www.mobilityguru.com/2005/10/25/squeezing_more_life_out_of_your_notebook/

[chame]

I have some information about Li-Ion batt.
In Ni-Mh or Ni-Cd, the charge stops depending on the current.
There are two types of Li-Ion, the standard stops charging when the "controller" detects at 4.1 volts per cell.
The new ones are called Li-Polymer. In this case they stops charging when each cell reach 4.2v.
I did some experiment with my laptop Batt. I purchase 3 cells of Li-Polymer 3,7v 5Ah. Then I remove the old Cells and soldered the new ones. The "controller" stops charging at 4.1v (its an old laptop), so the new cells are charged only in 20%.
I calculated based on the time laptop runs.

Then I Used the same pack in the standard DC power plug in the back of the laptop. The laptop works at 19v in that plug, I used 6 cells in serial. The voltage is 4.2v x 6 = 25.2v the first 20 min(risk for the laptop, but It worked for months without problems) , then it stabilizes to 3.7v x 6 = 22.2v for about 10 hours, and finally it goes slowly down 30 min more till 17v = 2.8v per cell. The the laptop turns off.

I think that you can replace the batteries inside the laptop battery, in the case you find the proper cells, similar size, same technology.

Here you can see the discharge rate for li-polymer batteries
http://newlist.ru/battery/Images/li_discharge.gif

And the batteries I used, they are big (13cm x 4cm x 0.5cm), but you can find smaller ones.
http://www.rcmaterial.com/HowLipoPackES_files/image011.jpg http://www.rcmaterial.com/HowLipoPackES_files/image025.jpg

[Flamingtaco]

I'm back...

I finally got around to purchasing 9 18650 cells to rebuild my pack. Here's the lowdown on the specs:

Original batteries = 1800mAh
Replacements = 2400mAh

Original packs:
Standard, two-stick pack = 3600mAh
Three-stick extended life pack = 5400mAh

Rebuilt pack = 7200mAh

Double capacity of the standard pack, 35% more than the extended pack.

This comes to 78Wh. If the laptop consumes at it's max of 70Wh, I get just about an hours worth of run time. That's max screen brightness, max CPU load, CPU fan on, HDD, DVD and floppy spinning, PC cards talking up a storm. Powering junk via USB. I don't think you can run a test that strenuous.

I'm going to build a carbon fiber case that will sit beneath the laptop and house at least four sticks of five 18650's. The cost to do this will be near the "big" battery packs, but instead of 110Wh, I'll get 180. That will provide 2.5 hours of max load. Probably enough power for a full day's activities. It will be a better pack, too, with an individual PCB per stick rather than one for the whole pack like the big battery makers use.

[Flamingtaco]

Found out the original batteries are not bad at all. The pack controller flaked out on me. Now I HAVE to purchase a new battery. Looks like I'll be using the nine I purchased to make a big pack soon. I think I'll do three series of 5 to start. Should be enough juice to run it all day long on battery.

[flamerail]

thanks for the tips!

[Cudor]

I picked up the Asus s96j. My dealer, who was quite knowledgeable compared to regular dealers who don't know what they're talking bout, suggested I recharge and completely drain out the battery for the first 10 charges, which will thereby elongate the battery life, and keep it at it's max charge capacity.

Any truth to this?

[K15]

The Li-Ion batteries are newer (the used to be more expensive but that has dropped now), and they don't suffer from the 'memory effect' as bad as NiCD batteries. NiMH is somewhere in between of them.


Ni-MH batteries suffer fewer drawbacks than Li-Ion (little danger in slight overcharge, no danger in trying to charge a full-dead Ni-MH, negating the need for controllers and switches to disable the battery.)
One problem though, Ni-MH does not have the density of Li-Ion, they are much bigger for a given amount of current. In fact, the miniturization of cell phones was not so much the electronics, it was the batteries. Look how thin and tiny the Li-Ion batteries are now in cell phones, consider the idle life (my phone lasts 3 days+ idle.) and then look at the NiCad or Ni-MH phones in years past, HUGE batteries. However, Li-Ion continues to improve in life, reliability and density. Improper use and heat are the big killers of Li-Ion batteries. Using the laptop plugged in all the time with the battery at 100% is not good.
1. Li-Ion does not like being at 100% charge.
2. Laptops are hot.
Li-Ion suffer ZERO memory effect what-so-ever. The closest thing to such a thing is the "fuel gauge" on the laptop or phone, completely unrelated to the battery.
Unless i'm mistaken, the fuel gauge problem happens due to the permanent loss of capacity in the battery, through abuse or normal use.
I don't know that though, so don't quote me:confused:

Something that was difficult and is STILL difficult for me to grasp is the fact that we can (and SHOULD) recharge Li-Ions often and without fully discharging them. I grew up with NiCads and the "fully discharge, fully charge" idea was drilled into me. LiIons not only don't need to do that, they shouldn't, or should as little as is possible.

[john_hk]

No advertising.

[DayUSeX]

damn spammer

anyways my laptop battery says 44% wear, and i never do anythign like discharge it, how would I go about getting it back up. Becuase currently I have about like 1:30 left on my batter when I unplug it when I used to get something like 4-5 hours =/

[ozzlo]

I would reccomend some Full deep cycles... Start at 100% drain it to zero and do it again... It dosen't always work, kinda depends on the battery like if it's a "memory"(kinda rare nowadays) thing or an actual internal corrosion thing

[pizzapieguy]

I have a question, is it good to leave the battery charger connected and still charging to laptop even though it has 100% battery life.

[Foolios]

I have a question, is it good to leave the battery charger connected and still charging to laptop even though it has 100% battery life.

If the battery is fully charged and you don't plan to use it anytime soon. I would suggest removing it as long as it doesn't pose a hassle to do so.

The reason being; heat is the enemy of the battery. The less exposure to it, the happier it will be. On the other hand, you could buy a laptop cooler and feel worry free. They will blow air under the laptop to help keep it cooler.

Anyone have any other suggestions?

[Foolios]

I do have a question about trying to revitalize what appears to be a dead battery. I have this one battery that won't charge up. I read that putting it in the freezer over night could fix it. It's a Li-on type. Think it'll work? If not, you know what might?

Thanks in advance.

[Bjm2587]

Good thread. I didn't know it was recommended to remove the battery if you plan on keeping it plugged in. I never move my laptop and it always sits on my chill mat plugged in and 100%. So just take it out at 100% and power it through the ac or should I discharge it first?

[Kittyhawk]

Please note that modding Li-ion battery packs is risky. Li-ion battery cells can EXPLODE or catch fire if overcharged or mistreated!

That makes them alot more dangerous than NiCd or NiMH batteries.

[Foolios]

Good thread. I didn't know it was recommended to remove the battery if you plan on keeping it plugged in. I never move my laptop and it always sits on my chill mat plugged in and 100%. So just take it out at 100% and power it through the ac or should I discharge it first?

I would take the battery out after it was fully charged until you needed it. Just don't leave it out for longer than a month without use. It's a good idea to use the battery up and recharge it at least each month. Keeps it in condition.

If it's on a cooler/chill matt, it should be fine to leave in all the time. But I would still use up the battery and recharge each month.

[doomtuba]

Oh man, you're not supposed to let the battery drain all the way every time these days? At least I know this now!

[myststix]

Switch to an LED screen, improves battery life by a ton!

[grishenko45]

great thread guys, i'm considering my 1st lappy, so this was helpful :)

[IgnitedX]

Maybe I ask what constitute as a "charge cycle"? If I charge til 80%, use it on battery down to 79%, charge it back up to 80% again, is it charge cycle? Obviously I am not doing that... just wanted to get some answers here. Right now I am still really confused in what to do to keep my battery healthy.

Which one should I be doing, given the choices:
1. charge til 80%, unplug, use til 20%, charge back up to 80%, repeat
2. charge til 80%, leave plugged but not charging (it actually says "plugged in, not charging" in Windows)

I am thinking 2 is probably the right choice, but I also don't know if Microsoft is lying to me or not... and it'll be too late when I find out if it is.

Also, if I leave my laptop unplugged for a day, and it loses 1% charge while powered off and I plug it back in when I use it to get it back up to 80%, that's a charge cycle? (only get 400-500 of these according to OP) :confused:

Advice? Excuse my noobness on batteries....:chair:

[cheapskates]

Wow so much info to take in... perhaps Too Smart, if you're willing, can you do a summary and update your first post? :D in order of most important to least important? Or if anyone else is up to the challenge!?