We all own more battery powered products than ever before, and in most cases those batteries are rechargeable. Laptops, music players, phones - they all have rechargeable power packs, almost all of them using lithium. These batteries don't last forever. No matter what you do, their capacity to hold charge will decline over time …
For really long life, never below 80%
Not practical, sadly, but if you've ever wondered how the batteries in a satellite last through literally tens of thousands of cycles (see LEO satellite eclipse experience), or for that matter how the Mars Rovers keep ticking after 5 years, it's because their batteries are sized such that they're never substantially depleted. They're never run down below where they have perhaps 80% of nominal capacity remaining. Less movement of "stuff" in the battery equals longer preservation of cell geometry.
Unfortunately that would mean a huge battery pack for a laptop if you wanted to use it for more than an hour or so.
Hubble engineers discovered a few years ago that conditioning the batteries on the telescope was actually ruining the batteries. Since abandoning the conditioning process the batteries on the spacecraft have lost little if any capacity, after losing something like 30% largely due to following conventional wisdom on conditioning.
A wonderful battery technology we're leaving untapped is simply improving the quality of software construction so that we don't need to have bomb-like batteries to accomplish things that would need less juice if software were better made...
What a fascinating and informative article, thanks Reg! More of this sort of thing please!
"Contrast that with the netbook battery sitting next to us, which although less than a year old will discharge from full in under 20 minutes."
Woah! What laptop was that, so I can stay away from it? Even considering you "abused" it, only 20 minutes is frightening... If my 1000HE's battery starts performing like that in a year or two, I'd be really pissed off...
I agree with Doug Bostrom
New laptop battery life seems to have been pegged around the 1.5-3hr mark for the past 5/6 years and I reckon it's because of bloat in OS and software negate any advancements in battery tech.
I always try and remove the battery when I use it plugged in at work. But when I got my latest laptop 4/5 yrs ago the battery supplied went to 0 within weeks, probably with poor usage patterns. But I've been caning my current battery for the past few years, running it down to maybe 50-60% daily on a 1hr commute and it still seems to work pretty well.
What I really want though, is the ability to hot-swap batteries without shutting down. So some sort of internal battery that gives you like 2mins. That would be cool.
Looking forward to getting hold of one of those 9hr EEEs next
The article sounds good and says "deep discharge (down as far as you can) your battery twice a week for best life".
The first comment sounds good and says "never deep discharge your batttery, it knackers them".
Would someone like to buy me a 2nd laptop so I can do a comparison?
My PowerBook battery maintained 80% of its capacity for nearly 4 years. It is still at 75% after 5 years 2 months. I still get nearly 2 hours useful life out of it which, depressingly, is more than many laptops manage now, even when they are brand new.
All I did was follow the advice here:
It isn't too dissimilar to the article.
I thought that ni-cads were the batteries which suffered from memory effect, & that lithium batteries didn't need cycling at all?
This article seems to indicate that lithium still suffers, albeit to a lesser degree. Hmmm....
Look no further for a hot-swap battery. Get yourself one of the old Psion netBooks. When the battery warning comes on, close the lid, slip out the old battery, and slip in a fresh one. Open the lid and continue your work. Oh, and you won't need to do it again for ten hours or so.
Got me one o' those 17 inchers
A few years back.
Battery life could suck start a Harley with bad piston rings right out of the box.
That hasn't changed.
My travelmate is roughly five years old and still keeps charge for approx an hour (and it had less than two hours when new). My cycle model is "never use the bloody battery unless you have to" :-)
A colleague bought a similar machine and would telework from the pub over a long lunch on batteries. His machine was dead in less than two years - alough it could be because it was a more modern machine?
So IMHO do not use the battery - keep it on full charge seems to work very well for me.
And yes - this is NOT the point of a laptop but I am a home based teleworker who often moves to the patio table "office" in the summer and a laptop is ideal for such travels. And before you ask we have a waterproof powerpoint and Rj35 on the patio :-)
The other advantage of a laptop is the built in UPS - who is going to lug one of those small suitcase sized bricks outside?
I keep getting asked when I am going to replace that "tatty heap of junk" when I travel on site but its just amazing how often thier new machines seem to die just past the warrany period - like it was designed in!
This article is pretty good. Also taking into account Mr.Bostrom's comment seems wise.
I've burned through two batteries so far, both only saw one year of life before crapping out. Interestingly, the replacements are lasting much (>4 years) longer.
Kinda reminds one of the cartridges you receive with a new ink-jet printer doesn't it, those always run down much quicker than a replacement pair. ;)
Speaking of long run-times.. anyone know where you can still (reliably) buy a new Asus Eee 901 in the UK? preferably from a company that will ship to an address outside the UK.
Laptops Direct never replied when I asked them about shipping :P
@Ben Bradley - such a thing exists
Quoth the Bradley: "What I really want though, is the ability to hot-swap batteries without shutting down. So some sort of internal battery that gives you like 2mins. That would be cool."
Many laptops have batteries that fit in their expansion bays (I have experience both of Thinkpads and Dells that have these). Although less capacious than the primary battery, they do allow exactly the kind of hot-swapping you describe.
I have two different laptops...
...both well over four years old, one Samsung and one Acer, and the batteries will still run the machines for more than 100 minutes, the original time on both when new was a little under two hours. No special storage methods have been used. What I have done is charge the batteries fully every two weeks, then used the laptops on battery power until the battery low warning comes up (around 30% power remaining). Then the batteries have been removed, and left on the shelf until needed, then charged fully ready to use. I have never used them on mains power with the batteries installed unless I was charging them.
So, to summarise, I recommend charging every fortnight, running the laptop on battery power until down to around 30%, then remove the battery and put somewhere safe until needed. When you know you will need to use the battery, simply charge it fully and away you go. Never leave the battery installed when using on mains power except for charging purposes.
I know many other people who use this method, and all have had excellent results.
Very good points and it sounds very feasible, but what battery technology do satellites/Mars Rovers use?
1) The old fashioned lead-acid battery in a car/bike is kept at nearly 100% charge most of its life, apart from cold morning (non)starting and accidental "oops-I-forgot-to-switch-off-the-lights" moments and usually lasts 5+ years, despite massive current drains for a couple of seconds each time the engine is started.
2) I have a NiCad powered automatic light in a cupboard that gets discharged to 0% regularly, and those batteries haven't failed in 5 years, and still seem to last as long between charges.
So two absolutely opposed charging scenarios, both of which work, but using appropriate technology.
I am just saying that what works for Hubble, won't necessarily work for a laptop.
Thank you. This helps explain why my MacBook battery only lasts ten minutes - I thought I was taking care of it by almost exclusively using it plugged in for the past couple of years.
I'm surprised the manufacturers (or operating system designers) haven't created better software management that takes battery care in mind. If I could tell OSX or Windows that I won't need the battery charged ALL the time, the laptop could manage a regular drain cycle itself without me ever unplugging it; and then I could turn this feature off when I go travelling. Or is that too sensible...?
Oh right, any excuse to bash Apple is it?
>"Apple machines are an exception, and others may be too: they auto-underclock the processor when the battery's removed, so despite being connected to the mains, they won't run at full strength. We think that's daft, "
That's not daft, it's obviously a very sensible move to conserve electricity so that you'll still get maximum operating duration even in the case where you've removed the battery while not plugged into the mains! Apple are just trying to be helpful!
@The Voice of Reason
Lithium's don't have the memory effect like Nicads, so only half discharging won't knacker the battery to the extent you end up with only half capacity in a very short time.
However discharge cycles are part of the lifespan of the battery regardless. So as the article says, it's the number of cycles that counts. Doesn't matter whether it's a full discharge or a cumulation of partial discharges that count for a whole.
But as also said, the other lifespan limit is time itself and nothing can stop that.
As for 20 mins on a laptop. Yep, my old Acer laptop got down to only 20 mins after 3 years :(. I did however have it on mains most of the time.
p.s. good article. Pretty much spot on what I've understood to be the case with Lithiums.
That has got to be the most boring, inconclusive article I've ever read. Wiring my fingers to a car battery would have been more entertaining (remember kiddies, always negative to left index, positive to right)
In fact, why am I even reading this website??!
@Wolf Clostermann @Ben Bradley
I think what Mr.Bradley meant was more along the lines of what many PDA devices such as the well known 'Pocket PC' devices from a certain deceased (in body but not in name) computer manufacturer featured in their days: these had an internal capacitor/li-ion cell with enough storage capacity to tide the device over while you swapped out the main battery for another.
Given the advances in capacitor technology (think 'Gold cap', 'Super cap', 'Ultra cap', 'Green cap' and the likes of extreme capacity capacitors) it would be entirely possible to add enough grunt with such a device to make a laptop able to survive a main battery swap while in suspend to RAM mode.
Perhaps when fuel cells for laptops become common place..
Keep your battery cool...?
This goes against my understanding of batteries losing there charge when exposed to cold temperatures. Think of your car battery on a cold winters morning. It will have just enough charge to fire the engine, even though it was healthy and fully charged the evening before.
On another note, I like to keep batties healthy and since onwning my first mobile phone, I do not charge it until it dies. Only then do I get the charger out. All of my phones held their full charge as well as it did when new. Even now, my 18 month old Blackberry battery will keep the phone powered for 5 days with average useage - the same as the day it was purchased, and yet many mobile users moan about having to charge their battery every other day, mainly due to charging them at irregular intervals when they still have plenty of current remaining.
When it's time to get a replacement..
Li-ion batteries also start to decay from the moment they're made. So that cute netBook that's spent 6 months in the back of the shop and probably the battery has spent 3 months before it was fitted to the netBook in the first place has already lost a good part of a year of its life when you buy it.
After 3 years of ownership you'll need to budget for a replacement any way.
Buying 'compatible' replacements are real dodgy as they're usually old batteries slipped by the manufacturers into their grey channel for some profit.
Makes you wonder how often you need to replace the Li-ion batteries in a electric car.
Well here's looking forward to Li-Sulphate batteries due out soon.Twice the capacity of Li-ion we're told. Then there's the nano-tubes versions also due out 'any day soon' promising another doubling of capacity.
You have to wonder about the design of charging circuits in laptops. Every other Lithium--powered device* I've owned, and some are 9 or 10 years old, has gone on working fine, but the laptops all seems to run out of puff after two or three.
*Electric drill (so old, it may even be NiMH), mobile phones, PDA's, MP3's and four cameras.
If I was cynical, I'd suspect it was deliberate...
350 cycles, 96%!
Oh yeah! 350 cycles and still showing 96% on an 18 month old MacBook. Key was and is to let the machine run down to 5-10% every couple of days, and then hook back up to the mains, just as the article says.
Re: Keep your battery cool
Kevin; NiMH and NiCd are both allergic to cold, but most batteries based on a lithium chemistry generally handle it fairly well.
Store li-ion @ 40% charged at ~freezing.
The only thing I didn't see mentioned here is manufacturing date, most lithium-ion batteries start to fade after a couple of years, regardless of the charge cycles/patterns applied.
NiMH was probably the best chemistry for long term use, but unfortunately they're heavier for the same power output. Short term thinking being the default these days means it was doomed.
Re: Keep your battery cool...?
My experience of the effect of cold on batteries (though mostly NiMH) from using phones and cameras up a mountain whilst skiing, is that the apparent charge does indeed drop dramatically in the cold.
However that doesn't mean it's lost charge. Take it back down the mountain and into the warm and it's back up to a decent charge.
i.e. the cold effects the performance of a battery, but not the charge.
Lithiums I'm not so sure. I've used Lithium based DSLRs up a mountain and never had a problem, but then DSLRs generally have very low drain on their batteries anyway.
would use disposables.
Apple kills batteries after a while - our battery dropped from 4.5 to 3.5 hours in two years (excellent! comparing with Dell that is now at 30 min instead of 4 hours) just suddenly stopped working. It had been recharged around 350 times (3 times a week), so I don't know if it is good idea to use it up to 95% few times a week.
Since when did rapid warming cause condensation?
>Rapid warming could cause condensation, and you don't want moisture forming inside your battery pack or laptop
Since when did rapid warming cause condensation?
You're taking a cold battery from a fridge into a warm and possible humid room.
The moisture in the air will condense on the cold battery. Warming it rapidly will actually reduce the amount of condensation present as the evaporation due to heat will start sooner.
However there is no way of telling how much condensation has formed inside the battery, rapid warming or not. Leaving the battery for a few hours first gives it time to warm up to room temperature and also for the condensation to evaporate.
Now all that's needed is putting it into practice
Fascinating. My first laptop was invariably kept with the battery left in and the notebook used on mains charge. Then I took it away and tried to use it on the battery - it lasted about 5 minutes. And THEN I discovered how much Sony charged for replacement batteries.
Since then I have (i) avoided Sony notebooks (and after other experiences, nearly all Sony products) and (ii) tried to preserve the life of the battery by leaving it out of the laptop except for the occasional need to take it off the mains.
Sounds like that's as bad as leaving it in all the time :(
However, I can't help wondering whether the procedures described in the article don't come under the heading of "more trouble than they're worth." Though, I suppose we should all be doing everything we can to maximise resources, and I do hate the thought of shelling out for a new battery to keep an old laptop running.
There's also the question of how welcome a spare battery would be in the fridge ...
I have a 3 and a half year old Compaq R4000 which is a desktop replacement laptop with a full desktop Athlon 4000 cpu in it (no sexy low power mobile CPU here).
It also has the standard 6 cell battery and not the bigger capacity which is available.
I use it on power regularly but I always make sure at least once a week I use it on battery till it hits around 15-17% battery left and then charge it up the next time.
After all this time I still get around an hour battery life. Not bad for its age and power usage.
I will get a new battery some time in the future.
23 months old
100% capacity available
High heat kills batteries...
...and is a particular problem if you own an Apple laptop which seem to be made for climates with an average temperate of 15C or assume that everyone will be using their laptop in a (cold) airconditioned office.
I live in the sub-tropics and given Apple's unhealthy obsession with 'thin', there is simply no way to keep their batteries cool, even with a cooling pad, a bit cooler yes, but cool, not possible. In the sub-tropics, these batteries get super-hot.
My oldish 17" Powerbook (1.33GHz G4) will quickly build up so much heat it will freeze or shut down entirely if I don't have it sitting on a cooling pad. Even with the cooling pad it killed a new battery within 6 months.
Just out of curiosity, has anyone else had this problem with this laptop model?
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