Hi So, according to some of my colleagues, it is common knowledge that you should not leave your laptop on charge for extended periods as that will reduce the life of the battery. But according to results from Google, this "common knowledge" is out-of-date or just plain wrong. Has anyone got links to any real results or would care to otherwise comment? Ta.
There's a lot of sophistication in the control of charging for laptops and phones (not in the charger itself, but inside the device). Sometimes they will partially discharge batteries before charging. Some will learn at what times they are likely to be plugged/unplugged/ used, and adapt their charging behaviour accordingly.
Unless the manufacturer has specific instructions to the contrary, just use it as a normal person would - as that is the usage pattern it will have been designed for.
Lithium batteries are known to last longest when half charged and cool.
You can work out the rest.
One theory is that it's to do with being a shade too hot for a long time which has a detrimental effect on batteries...
But batteries will degrade anyway and charging technolgoy is always improving. If the whole unit doesn't feel hot to the touch it's probably OK.
My old (well 4-5 years now) Acer 5050 is still going strong and gets the best part of 2 hours on a charge, but my slightly newer Acer Aspire One is down to about an hour now after nearly 2 years. I'll probably spend
30-40 quid on a new one for it as there's life in it yet (I upgraded the RAM recently too)Gordon
Most laptop batteries are now Lithium Ion. You can find a lot of information on maintaining L.ion batteries by doing a Google.
Lot of info here:
"The question is often asked: Should I disconnect my laptop from the power grid when not in use? Under normal circumstances this should not be necessary because once the lithium-ion battery is full, a correctly functioning charger will discontinue the charge and will only engage when the battery voltage drops to a low level. Most users do not remove the AC power, and I like to believe that this practice is safe."
From perusing a number of websites it appears that fully discharging a L.ion batter can permanently damage it. They have no 'memory effect' and so recharging after just a small discharge will have no deterimental effect.
I keep my laptop plugged into the mains all day every day - although I shut down the device and switch off the power overnight.
Well my not that old Acer laptop needs a new battery. And it has hardly ever been used on the battery. But left plugged in to the powered up PS pretty well permanently. So either these batteries have a short life, or the charging circuit is rubbish.
Grumps explained :
I would suggest that you ought to occasionally run it from batteries and that you should never leave it on charge as a permanent thing.
I use mine only very rarely, when I'm busy researching something maybe late at night in bed. Between uses I remove the AC power and only plug it in when actually being used. I've run it like this for a couple of years and battery life is still close to original.
Epirical evidence regularly shows that Li-Ion batteries left fully charged lose their capacity in very short order. The cavalcade of year old laptops (& phones & MP3 players) I see that will run for 10 minutes on a 'full charge' is legion.
My 5 year old laptop battery which is kept half charged in a drawer has almost all of its original run-time when I use it.
*If* there is an amendment to 'common knowledge' it'll be to do with a more intelligent charging algorithms (Li-Ion doesn't like heat, fast charging (which causes heat) being over-charged or over-discharged) or a different set of wear conditions in the replacements (Li-Poly or thin-film versions etc.)+1
All chargers are in effect voltage limited, so a 'base camp' charger is one that pushes current in until the cells reach full charge voltage, and leaves them there.
This is not ideal for long term life, but it does mean that when unplugged, the battery is full.
Since is is not possible to predict when this will happen, there is no algorithm that will ensure optimal battery life without human intervention.
Ideally the battery would be maintained at half charge all the time except just before it was due to be used off mains.
I suspect therefore that it is less that chargers have changed markedly, and more that the battery technology has been tweaked to nullify, or at least minimise, this problem. I.e. instead off going for capacity, low weight or high discharge and cycle rates, the development focusses on long life at very modest cycle requirements.
Ha! I wish I could work that one out for my own use. Takes mine (4.5Ah) about 3hrs to do a full charge so 1.5hrs to top up out of the drawer but I never realise I want it until about 5mins before I step out of the door!
For historical reasons, now I'm retired, I have a whole bunch of laptops. The one I'm typing on now is permanently plugged in, it's a few years old and still keeps a reasonable charge - about an hour, I'd guess. The others are plugged in as needed, and left plugged in for at least the rest of the day.
The ones that are hopeless are the older ones that are hardly ever plugged in and just used to pull data off or to see if they still work. In general I need to keep them because they have, for example, development software on them from defunct companies that can't be transferred because I can't get registration codes.
My guess has always been that the chargers are fairly crude, but the charging circuits inside the machines are pretty high tech. Somewhere in a drawer I have a replacement charger chip for one of the older machines. It has a lot of pins. I showed it and the problem motherboard to a local approved mobile phone repairer, we discussed and I replaced the machine rather than give him the stress of attempting repair.
Yes, but the battery's control circuitry won't allow you to fully discharge the cells. Because it can damage it, and because it's difficult to recharge fully discharged cells.
Modern Li Ion batteries are not just a collection of cells plus some metal connecting them together. There's also control circuitry that's integral to the battery.
You could virtualise them. That way you dont need to keep lots of laptops, just their image and run it within another machine when you need to access the software on it.
Alan
Some are :-)
The stuff you fly model aircraft on are exactly that.
And boy, did they push the limits and establish what made them explode...
There's also control circuitry that's
Only on consumer goods where catching fire is not an acceptable failure mode :-)
My 4.5 year old laptop battery which has spent most of its life in a laptop connected to the mains still has a fairly high capacity, so I suspect the ones failing within a year are low quality.
That's running on mains with the battery in place. Any laptop charger will reduce the charge to a trickle when the battery is charged. Just feel the temp of the charger when charging and when charged.
MBQ
Some chargers don't fully charge the Li Ion battery, enhancing its life. It seems the higher the terminal voltage, the faster the deterioration of the battery. Li Ion batteries have a terminal voltage dependent on the state of charge.
Some laptops have the option in the BIOS to only enable charging up to "80%" for just this reason.
very good idea.
In message , AlanC writes
This is mainly audio development software plus C++ hardware control and other stuff and I have always shied away from virtualisation with any of that as I've thought you have to run new and complicated hardware that can pass interrupts to the virtual machine. As is obvious, I know very little about the subject.
It does seem like a good idea, though.
Actually, there is one more reason - the older machines have separate audio boards that are good enough to carry out performance tests on equipment. Newer machines with the AC97 and HD Audio abortions mean I also have to take along an audio interface as well as the machine and isolating/balancing transformers.
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