Laptop batteries - wasteful ?

Channel Hopper

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Without putting a meter on hidden connections, can anyone give me an answer ?

The wifes laptop is now in need of a new battery, the old one works for about ten minutes before the critical/shutdown message appears.

Since the machine still works fine on mains power, is the supply still being used all the time it is running to provide a charge to a knackered battery, or is there a cut off point at which the laptop knows there is no point in diverting energy from the power source, which is just going to waste ?
 

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I think the charger just keeps on pumping electricity into the battery - the laptop will probably keep working even if you take the battery out completely, which is the equivalent of a completely knackered unit.

Laptop batteries should be considered as consumables that need replacing every so often.
 

PaulR

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I always advise people who use a laptop as their main computer to take the battery out and run on the PSU alone.

Lion batteries have a lifetime determined by the number of charge cycles they are put through. Leaving them in means they are permanently on charge and will have their lives frittered away for no purpose. I totally knackered the battery in my old HP laptop this way until it literally held no charge at all. Most of the laptops in school have their batteries left in while they're on PSUs and they're useless in a year or so.
 

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Just awaiting a new Lion for my Netbook - it is down to 50% capacity after about 800 cycles: Interestingly, unlike NiMH which should be deep-discharged every now and again, I discovered whilst Googling to check whether my Netbook Battery had had a good life that you should NOT run them right down, nor should you leave a fully-charged one in place when using Mains Power.

For Lion, charging from about 40% is apparently best.

That said, mine is used for several hours a day on Battery, including two discharge cycles, so for £22 to replace it with one of twice the capacity (4400mAH instead of 2200) is good value.
 

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I've given up with batteries in my Acer Aspire netbook. I just use it now plugged into the mains. THe first one refused to charge up after leaving it off for a few days, and the second new battery didn't charge up at all untill I updated the BIOS (a known problem with this netbook). Then the battery just died after a couple of days even though it was supposed to be charging up.
 

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I've managed to knacker the batteries on every laptop I've owned.
 

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Analoguesat said:
I think the charger just keeps on pumping electricity into the battery...

That's what I was hoping to confirm by asking. I suppose I can verify by checking the current consumption at the wall socket, with battery out of the circuit, in but dishcarged, and then fully charged, to see if there are changes.
 

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Received my replacement battery yesterday: Old one was 3 cell 2200mAH and down to less than 50% efficiency.

New one is 6 cell and 5200mAH capacity.

Charged it up and my battery monitor estimated 6.5hr endurance, which has gone up to around 8hr as it accumulated better actual consumption data.

Also, I have done some more reading about LIon batteries in the wake of the comment earlier in the Thread that they should be removed except when needed: The charging circuits actually determine from the attained charge when the battery is "full" and then turn off, so there is no trickle charge, in effect.

That said, various articles contradict each other, so a reliable modus operandum is hard to judge.

In my case, I have mistakenly been deep-discharging both my Netbook and SWMBO's Laptop batteries and there is agreement that that is not a good thing to do.

So my M-O will be to leave the batteries in place, discharge them only to around 40% and, if I ever do take them out, make sure they are charged to between 40-100% before storing.

Edit: Now up to 9hr endurance after using it on battery alone for thirty mins. last night and another thirty or so just now. Showing 89% full.

Looking good - Even if it only lasts a year, £23 is good value.
 

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Tivù said:
The charging circuits actually determine from the attained charge when the battery is "full" and then turn off, so there is no trickle charge, in effect.
I suppose that it's possible that not all Lion batteries, especially when they were first introduced, have this circuitry but my practical experience with everything else, including a Macbook Pro, is that they don't.
Tivù said:
So my M-O will be to leave the batteries in place, discharge them only to around 40% and, if I ever do take them out, make sure they are charged to between 40-100% before storing.
Sounds like what I do except that I'm not fussy about not letting them get below 40%.
 
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