laptop battery life on mains

Balfa

Me mammy's laptop (acer) manual says that if using the laptop on mains power for extended periods, to remove battery, as battery life will be SEVERELY shortened by leaving the battery in fully charged and running off mains.

I've never heard of this before. Is it specific to some laptops? or does it happen all laptops? or is it complete billox?

i use my dell almost exclusively on mains and never remove the battery, and i hope i haven't been killing my battery all this time!

tomk

I can tell you from personal experience that your mummy's manual is right, and that you've probably fried your own battery - sorry.

I used my laptop almost exclusively on mains for 2 years, and got a nasty shock when I discovered that my battery's life was about 30 minutes. I had to go and buy a replacement battery, and I am now obsessive about removing it when on mains.

Goodshape

Havn't heared this before. Is it a common 'feature' on laptops?

I run on mains almost all the time, but the cable isn't the most secure - if I had to take the battery out it would be powering down half the times I move the machine forward.

Saruman

Most laptops suffer from this i think.. you know it would not be too hard to have a cut off to stop it overcharging!!!

NotMe

That's crap. I use my laptop on mains all the time. It would be a pain to keep taking the battery out because the mains wire often comes out and that would mean the machine rebooting.

tomk

Goodshape wrote:

Havn't heared this before. Is it a common 'feature' on laptops?

It's a 'feature' of rechargeable batteries wherever they are used.

Goodshape wrote:

I run on mains almost all the time, but the cable isn't the most secure - if I had to take the battery out it would be powering down half the times I move the machine forward.

NotMe wrote:

That's crap. I use my laptop on mains all the time. It would be a pain to keep taking the battery out because the mains wire often comes out and that would mean the machine rebooting.

Goodshape, NotMe - how long have you been doing it, and when's the last time you checked your battery life?

I reckon you'd find a similar warning in your own manuals, if you still have them....

RicardoSmith

Recently found this out myself and my battery life which used to be an hour (its a desktop replacment so it was never good) a year ago is now about 30 mins. I haven't bothered taking the battery out since though as I only use it on battery to move from one location to another in the house without rebooting. So 5 mins would be enough. I might source some cheap replacment batteries in the future. Its a pain though as the batteries in mine are not easily removed.

What you need is a charging station and always use the laptop on the battery. Or a cut off switch.

Is this why iPod batteries don't last? Since they recharge if plugged in all the time?

dearg_doom

Yep it's a feature of all rechargeable batteries.

It's to do with the chemistry inside the battery,

Most r/c batteries will be optimised for a given number of charges befrore the max possible charge becomes approx half of what it was when new.

eg for most phones the batteries will be optimised for approx 500 charges.

which should provide for over 3 years of reasonable charge, ie the battery will be plugged in approx once every 3days.

This obviously used to be a lot more of an issue than it is now due to tech advances etc...

Also it is related to how many times the battery is connected to the mains (plugged in)

it has nothing to do with how much the battery is charged at any one time

Which means that if you were to plug the phone in my example above in 3 times a day, every day, you will only get one years use out of the battery!

I think this was the main cause of the iPod's problems.

Balfa

i have the same problem with a dodgy power connector that sometimes just falls out. that's why i haven't been taking the battery out even after i heard this. they need to make the connectors much better.

and it really should be easy to cut power to the battery once it's charged

It looks like my battery still has almost two hours of life on gentle browsing. i think it had almost three hours when i got it, so that's not too horriffic a loss, but it does mean any flights i take are going to be one hour boreder than before

Mothman

In my manual (Dell 510m)

"You can leave the battery in the computer as long as you like. The battery's internal circuitry prevents the battery from overcharging."

My mains connection also disconnects easily, but from the reading of my manual, I don't need to remove my battery when I'm on the mains.

Tar.Aldarion

my acer battery life is like an hour which is so pathetic.i never take out the battery.oops!

stagolee

Mothman wrote:

In my manual (Dell 510m)

"You can leave the battery in the computer as long as you like. The battery's internal circuitry prevents the battery from overcharging."

My mains connection also disconnects easily, but from the reading of my manual, I don't need to remove my battery when I'm on the mains.

:eek: i hope thats the same for my inspiron 8600
id heard of this with phones but i didnt realize it also applied to laptops

forbairt

hmm... I think this would explain why suddenly .. the gf's laptop has a very short battery life span ... oh duck!! .. :eek:

lomb

i think the better dells disconnect the battery when its fully charged.
i suppose u get what ya pay for.

Capt'n Midnight

Sealed Lead Acid batteries (never used on laptops) can be killed by overcharging. A UPS should be tested every few months because of this. If you use the laptop on battery at regular intervals then that reduces the chance of overcharging, and it's probably a good idea to let the battery run down most of the way once in a while to get a deep discharge.

lomb

Capt'n Midnight wrote:

Sealed Lead Acid batteries (never used on laptops) can be killed by overcharging. A UPS should be tested every few months because of this. If you use the laptop on battery at regular intervals then that reduces the chance of overcharging, and it's probably a good idea to let the battery run down most of the way once in a while to get a deep discharge.

i thought it was never a good idea to run down li ion batteries below 50% as to do so markedly shortens their life.
a full run down is only needed when the battery level indicator is faulty and running down the cell resets it.

most liion batteries at 2.5 years have lost 50% of their capacity. therefore laptop batteries are unfortunately a replaceable item...............

RicardoSmith

Mothman wrote:

In my manual (Dell 510m)

"You can leave the battery in the computer as long as you like. The battery's internal circuitry prevents the battery from overcharging."

My mains connection also disconnects easily, but from the reading of my manual, I don't need to remove my battery when I'm on the mains.

My understanding is that overcharging (charging a battery too much/too long) is a different issue than charging/draining a battery too often. Its the latter we are talking about here. Though I'm not very knowledgeable about batteries and the different types etc. Is this the same as the memory effect on phones? or is it simply that the battery wears out, loses the ability to hold a charge.

Capt'n Midnight

lomb wrote:

most liion batteries at 2.5 years have lost 50% of their capacity. therefore laptop batteries are unfortunately a replaceable item...............

Off Topic
Sealed Lead Acid are deep discharge and can go down to 20% happily
The other type of Lead Acids in cars is for cranking and shouldn't drop below 80% full charge.
Must ask Mr. Google about Li-ion, though that sounds strange in light of the use of them in Hybrid cars.
No one guarantees batteries beyond a year anyway and yeah they are treated as consumables , bit like the photoconducter in laser printers

lomb

deep discharge indeed damages them see here http://www.electronics-lab.com/articles/Li_Ion_reconstruct/

Capt'n Midnight

Nice link Ta. - PDF version 1.6MB How to rebuild a Li-Ion battery packhttp://www.electronics-lab.com/articles/Li_Ion_reconstruct/How to rebuild a Li-Ion pack.pdf

Looks like a little trip in to power management is in order - hibernate earlier than 2%

Tip: To increase battery life store it at 40% level at low temperatures (even to the refrigerator but not below 0 degrees Celsius) and never discharge it full. Charge it early and often. Excess heat can damage the battery. Also charge once a year to prevent overdischarge.

lomb

hmm seems most batteries have panasonic liion cells and can be repaired for 60 euros inc postage and a bit of soldering.
to put it in perspective a targa laptop battery is 170 euro inc postage.

norbert64

Sadly read about this a few weeks back, using your laptop on mains pretty much all the time, will indeed harm the battery somewhat.

I guess it prolly depends on the make of laptop & battery though.

zAbbo

hmmm 4.5hrs on my powerbook, would be lucky to get 2hrs on my hp windows thing

lomb

any centrino laptop can match the powerbooks for stamina. the intel pentium desktop laptops are hopeless, the amd 64bit ones are too power hungry too. i believe aqmd are coming out with a centrino beater soon.

oneweb

The worst thing you can do with the newer rechargeable batteries is let them run to empty - you're better off topping them up regularly - the days of letting them run dry are GONE! I've also heard that leaving a battery in constantly while a laptop is plugged in can reduce the battery life. I found this with sis' laptop - used to have about an hour's power but now it's max 30 seconds :-/ (it's a few years old tho so the technology will have improved) Still, I'd rather take it out when I don't need it.

norbert64

Silly me, could have easily just removed the flippin battery from my laptop.

Gonna do that now.

NotMe

There should be a switch on the bottom of the laptop to disable the battery.

SouperComputer

Mothman wrote:

In my manual (Dell 510m)

"You can leave the battery in the computer as long as you like. The battery's internal circuitry prevents the battery from overcharging."

My mains connection also disconnects easily, but from the reading of my manual, I don't need to remove my battery when I'm on the mains.

its not overcharging thats the problem. Li cells have to be kept exercised and within certain voltages. keeping any battery at 100% will kill the cells. some manufactuers seem to have built a system into the PMU whereby when it reaches 100% its allows it to discharge to about 95

in any case, "strecthing" the battery occasionally, letting it run down fully and or storing it at 40% charge will help it live much longer.

NotMe

So if I'm using my computer for a long time would I be better off running on battery power until it gets to say 50% and then plugging it in until the battery gets up to 100% again and then unplugging again etc..?

Sparky

I have a Dell Inspiron 9100 and since its a desktop replacement the batteries are always connected and the battery even has a sub woofer in it, surly a company like dell would have a small relay to disco the battery power,
this issue also explans why in my packard bell laptop which spent most of its time connected to mains, one day just started bleeping after 5mins, i though mabey the power connector was not in fully hence less battery life, but it drans from 100% to 65% in a blink of an eye, packard bells place in portugal were looking for €100 of me for a new battery 50 quid for the battery (not bad) and 50 for delievery. but i still hav'nt ordered it yet.

stagolee

NotMe wrote:

There should be a switch on the bottom of the laptop to disable the battery.

you would think it would be automatic when it hit 100%
i prefer running mine on mains whenever possible as the screen is much brighter that way.the battery is now out of the machine for the first time in its life

RicardoSmith

stagolee wrote:

you would think it would be automatic when it hit 100%
i prefer running mine on mains whenever possible as the screen is much brighter that way.the battery is now out of the machine for the first time in its life

How would they get you to buy batteries more often then?

Change your power settings...

dawballz

stagolee wrote:

you would think it would be automatic when it hit 100%
i prefer running mine on mains whenever possible as the screen is much brighter that way.the battery is now out of the machine for the first time in its life

You can change how bright the screen is whenever on my laptop by pressing the FN key and another key(left/right arrow to be exact). Also on my lappy this setting can be changed in the BIOS(i think).
Methinks we need a laptop forum