Should I Run Laptop On Mains Or Battery Power ?

[Trevor]

My power transformer goes quite cool once the battery is charged. Should I disconnect and run on battery, or possibly pull the battery slightly off its contacts, in order to maximize life? In that case, are batteries best kept unused charged or discharged? Thanks.

[Guest Reimar]

My power transformer goes quite cool once the battery is charged. Should I disconnect and run on battery, or possibly pull the battery slightly off its contacts, in order to maximize life? In that case, are batteries best kept unused charged or discharged? Thanks.

If you run on Battery, the speed of the laptop slows down. Keep the battery charged and disconnect the battery if you use the laptop at home but keep in mind that the system will down directly by power cuts!

I use my laptop at office and home without battery but connected the power supply to an UPS. That works fine and safe!

[Phil Conners]

With the new Ni-Ion type batteries the biggest problem you'll face is if you run it all the way down, they don't like that and sometime die an instant death when it happens. I don't think there is any point in disconnecting it, a new battery is cheaper than a UPS

[phazey]

Run the battery nearly down. then recharge. the thing about batteries is that they have a memory - so if you part discharge and recharge, it seems to think this is the starting point for the next recharge. over time your total usage will deplete (my old compaq went from 4 hours down to 10 minutes over the period of 3 years). it's a trick also used in RC stuff....always discharge completely before recharge.

i do it once a week just to be sure with the new lappy.

[backflip]

The industry standard Li-Ion batteries do not have a memory, so that isn't a problem. The batteries have a life of 400-500 complete charge/discharge cycles. If you run on the battery only, you'll use up a battery pretty quickly. You can use AC power only, but there is another problem. If a Li-Ion battery is COMPLETELY discharged, it can become unstable and you might find that:

- you cannot recharge the battery

- the battery reverses polarity, and things go pear-shaped quickly after that

To prevent any of this, it's best to run on AC with the battery installed.

[oooooo]

i couldnt agree with backflip anymore other than that i would recommend using full charge/discharge cycles. major manufacturers actually recommend complete battery drains before recharging.

[Simmo]

As backflip mentioned Li-Ion batteries have no memory effect so any advice about discharging and charging cycles is completely useless. The major problem with Li-Ion batteries is their limited lifespan. A laptop battery can lose 50% of it's capacity in as little as 2 years depending on storage temperature.

Remember all the Ipod battery fuss a few years back , that's what it was about.

When buying a laptop battery always check the manufacture date.

[chingching]

I have read that batteries will have the longest life (WHEN UNUSED) if kept at 40% of their charge

[Firefoxx]

1. Memory effect only affects certain older battery types. Not the ones used in modern laptops (usually lithium ion or lithium polymer). The longest life at 40% thing applies to these batteries, but only when stored unused for very long periods of time. They *cannot* be deep discharged because of protection circuitry.

2. Batteries used in modern laptops have both a finite number of charge cycles (around 500) and a usable life (around 2 years), after which the capacity begins to drop.

If you charge your battery and then unplug and use only the battery, you're using up one of its finite charge cycles, which means you're shortening the battery life (and you're running slower on battery power). You could go to the extreme and always unplug the battery when on mains, but that's a bit troublesome, and the battery will run out of usable life no matter how you conserve it. Basically just use it as you would normally use it, and plug it when you have a plug. With normal use, you'd need to change the battery within a few years (if you want to have the same capacity).

[backflip]

"major manufacturers actually recommend complete battery drains before recharging"

Hmmm, I worked in the Apple PowerBook, iBook, and iPod divisions for a dozen years, and Dell notebook division for a couple years, and I never read that.

After a complete discharge, it is imperative that the battery is recharged within 24 hours...else you can damage the battery as I mentioned.

[drake]

Firefox explain it correct.

Let the Notebook if possible with Battery on Power line.

A Notebook-Battery consist of few single Cells, each controlled by special IC.

more info (basically for OEM's ) at:

www.panasonic.com/industrial/battery/oem/images/pdf/Panasonic_LiIon_Charging.pdf

and

www.panasonic.com/industrial/battery/oem/chem/lithion/index.html

cu drake

[nikster]

good info guys...

alternately, you could do like me and use the battery in the worst way possible so it dies within the 1 year warranty, then get a new one for free.

i don't do it on purpose but my usage pattern seems to be such that this happens every time

[Guest Reimar]

With the new Ni-Ion type batteries the biggest problem you'll face is if you run it all the way down, they don't like that and sometime die an instant death when it happens. I don't think there is any point in disconnecting it, a new battery is cheaper than a UPS

Phil,

you maybe never bought a Laptop Battery?! Most of the Laptop batteries starting above Baht 4,000.00 while a UPS with 800 VA cost below Baht 2,000.00.

But it is true that the power supply/charger for the laptop gets quite hot with battery connected and is mor cool without! On my old Compaq Presario 2500, I used until last October, I had 2 PW's down with battery connected but after I used the laptop without battery the PW was never a problem. My new Acer 5593 I used in my office and at home on PW only. With battery connected the PW get that hot that you want hold them more than 30 sec. in your hand! But as wrote in my first answer, keep the battery charged before you disconnection and preiodly charge the battery maybe once a month.

[RAZZELL]

I use my MacBookPro "plugged in" with a battery connected...

Although I have two batteries and swap them over every week or so to prolong their life...

RAZZ

[elkangorito]

Most alkaline batteries (Nickel) have a much greater tolerance of complete discharge & over-charge compared to that of acid electrolyte cells. Not withstanding this, it is never a good idea to completely discharge a battery. A battery is simply stored energy, for which you have paid. By not using it, you will lose money as every battery has something called 'local action', which is the self discharging of the battery. Chemistry is a complex subject but chemical reactions all behave similarly to heat ie an increase in heat = an increased chemical reaction. Therefore, if you wish to preserve your battery when not in use, put it in the fridge (not freezer). But don't forget to allow it to come up to ambient temperature before using it.

The basic idea is to use your battery for what it is before it dies, otherwise you have wasted your money. Not withstanding this, it is always good practice to 'exercise' your battery by using it WITHOUT it being plugged into a charger.

Edited March 9, 2007 by elkangorito