laptop batteries

[ghorjus]

i've been searching around the web whether laptops should be unplugged or continuously plugged <if AC is available> to properly take care of the batteries. i've heard that the batteries should be cycled <near empty then charge> and some say that laptops should be plugged given the chance. both says that it helps prolong the battery life.

the question now is: what is it really? got an old laptop which has a dead batt after years of use. know a few friends that had laptops that had their batteries almost dead in just a few years..

thanks!

[bozodog]

I found a bunch of understanding and knowledge at battery university.

[ghorjus]

thanks!

I will read this stuff...

[Pete_C]

I do not recommend leaving the laptop plugged in and powered off if the battery is fully charged. While modern rechargeable batteries (LiON) do not suffer from the"memory" issues early NiCad batteries did (where if you recharged it before it was fully discharged, it might eventually remember that level of charge as being all it can take resulting in a weaker and weaker battery each time it was charged), no battery is infinitely rechargeable and there is a risk if protection circuitry fails and the battery gets overcharged. Plugging it in while you work so that the battery is maintained should not cause any real issue, none the less you should periodically run it on battery alone and let it fully discharge and then fully recharge it to make sure the electronic battery meter is reset and recalibrates correctly. Otherwise you can wind up with a situation similar to the memory issue where it charges the battery less and less each cycle until it barely gives it any charge and it is as if you have a dead battery.

I also prefer to recommend going for the heavier duty battery pack (12 cell versus 6 cell for example) when available. More milli amp hours of power is good, just like buying a bigger battery for your car. If your car requires 350 cold cranking amps and you buy a 450 CCA battery which is expected to decline to half power in five years, then it may only last two years before it has trouble starting your car and will need a jump if it does not start on the first try. But if you start out with an 850CCA battery , then even after five years if it is outputting 425CCA it can still start your car.

[isteve]

I take care of 90 laptops used by school students in classrooms. I keep the laptops plugged in and powered off whenever they are not in use. Sometime during breaks this can be weeks or even months during the summer. We have never had a battery overcharge. We also have some that still have the original batteries that are going on five years old.

With all the students and teacher laptops we service probably over 1000, I find most batteries last about three to four years.

[marsh_0x]

I do not recommend leaving the laptop plugged in and powered off if the battery is fully charged.

Hi Pete, could this be the 1st time to ever disagree with you my friend ?

All my laptops have been on charge almost 24/7, mostly desktop replacements, occasional war drive's on the cig/pipe lighter.

Ni/Cad is a bird of a different feather, great for maintaining the high voltage level before the voltage drop off curve takes a deep dive.

Example 20 years ago as a ham with ARES (Amateur Radio Emergency Service) said to another ham/pilot, I topped off my battery packs, the memory effect, admitted he did the same and of course broke the rule but critical to maintain ground contact in the CAP (Civil Air Patrol) plane, searching for lost soul later found 2,000 miles away, but we tried.

Lead-acid as in vehicles demands a trickle to maintain a charge and loves it for years.

NiMH (nickel-metal hydride) remains a favorite for return on the money, discharge/recharge a thousand times, loves a top off anytime.

Shelf life (longevity to maintain a charge) is amazing.

Now comes lithium-ion, my favorite

Built into each pack, the protection circuit limits the peak voltage of each cell during charge and prevents the cell voltage from dropping too low on discharge

My laptops fail long before the battery does, IE a Toshiba from 7 years ago $2,200 still maintains a charge tho the GPU is gone.

Not a guess what the future holds with battery transportation cars.

Hi Steve, you understand well with experience...

Marsh

Edited January 27, 2011 by marsh_0x