battery charging

I know that my laptop battery wont last forever, so i want to get the most out of it. What is better, leaving my laptop plugged in and 100% charged while i use it or just unplug it at 100%, let it die then charge again?
What is best?

 

As I was saying previously in another post. Fully discharge your batteries before recharging.

http://www.hardwarehell.com/battery.htm

 

ya but also, does it hurt the battery if i just leave it charging at 100% while i use it?

 

No, it doesn't hurt the battery. You're drawing power from the AC adapter and not through the battery. In addition you essentially have a battery back up in the battery. If your power goes out the battery will keep your laptop powered on so you can save your work or you can continue working.

You can choose to run your laptop from the AC but then your laptop battery will be slowly discharging over time. When you put it back in it will recharge from whatever point it has discharged to.... if you do this repeatedly it'd form a memory.

 

NO!!!!!

You put a LOT of strain on your batteries if you fully discharge and then fully recharge. This is the OPPOSITE of doing good for your battery! It kills it faster than charging at smaller intervals! Lithium Ion batteries aren't like that at all.

 

Polarix.... there's a lot of contradictory information about this. This is a good discussion though.

8. Take care of your battery - Exercise the Battery. Do not leave a charged battery dormant for long periods of time. Once charged, you should at least use the battery at least once every two to three weeks. Also, do not let a Li-On battery completely discharge. (Discharing is only for older batteries with memory effects)

http://www.friedbeef.com/top-15-ways-to-extend-your-laptop-battery-life/

It's best to use (and especially charge) your batteries at room temperatures. Extreme conditions can drain your battery quickly. Also, avoid partial charges and use the battery until it is dead. Battery experts liken partial charges — and discharges — to eating a cup of lard every day. It significantly shortens your battery's life. Considering that a lithium-ion battery can explode if it's improperly used, it could also shorten your life.

http://www.microsoft.com/smallbusin...y.aspx#tipstoextendthelifeofyourlaptopbattery

 

If possible, one wants to avoid discharging a Lith-ion battery completely. They are happy down to around 40%.

For what its worth, the battery on my Inspiron 1520 has been in the laptop running on AC Power for a year now and I still have good capacity with it.

 

Not with the current technology. Full discharges are bad.

 

Down to only 40% seconded.

 

Where are you getting this information from? Sources would be nice.

The last laptop battery I had a problem with was an Inspiron 9300 and that was from never being used. The battery sat around for several years (I purchased it as a backup) and when I went on battery power it could hardly hold any charge.

My xps m1730 has no battery life but that doesn't count... I think I would need a portable generator.

 

I've heard both things too. However, I had a problem with my MBP battery lasting only 20 minutes and the way I fixed it was by draining it completely and then recharging it (as told by Apple support) and that seemed to fix it.

 

http://www.batteryuniversity.com/
ENOUGH. so many myths around this.
DO NOT FULLY DISCHARGE A LITHIUM-ION BATTERY.
to storage, charge/discharge it at 40% and store it in a cold environment. (ideal 5ºC 0% humidity).

If you are using your laptop with a AC, REMOVE the battery and store it.
DO NOT LEAVE IT PLUGGED AT 100%.
If you want to fully charge the battery, unplug the charger at 100%. If you leave it charging every time (over night for example) at 100% the battery capacity drops about 50% in about 6months.
ALSO it's VERY important to charge batteries in a cold environment. (ideal 5ºC 0% humidity).
A battery in a 60ºC environment lasts less 50% then in a 30ºC.

ALSO NOTE: Li-ion batteries are a LOT different from NI-MH ones. They require a different maintenance. Li-ion batteries don't have memory effect. Even if the manufacture of the Li-ion battery says to fully charge and uncharged due to memory effects that's NOT true.
Uncharged a Li-ion battery only to calibrate it.

 

Yeah, sometimes they need recalibrated which a full drain will do. However, constantly draining the battery is going to ruin it.

 

A very good site for info on batteries.

Yes. Most of them are based on how NiCad and NiMH batteries should be treated.

But that is a myth. The site you quote states to "Avoid frequent full discharges". Occasional full discharges are necessary for some batteries to calibrate the battery level gauge. If you had said not to fully discharge a LiIon cell, I would have agreed. And this is the reason that all LiIon batteries have a protection circuit built into them (to protect the individual cells voltage from dropping to low and being damaged).

There is another myth here. Firstly, yes, heat is bad. The more heat the shorter the battery life.

But, once a LiIon battery has reached 100% charge, the charger will turn off. So, they cannot be left "charging". In fact, the charger won't turn on again until the battery level drops to a certain point. For the laptops I have checked, this is 95%. If you unplug the laptop, let the battery charge level drop to 96% and plug back in again, the charger will not switch on. Let it drop to 94%, and it will.

If there is a problem, it is because the battery is being kept hot by the heat of the laptop. I haven't seen figures as bad as you quote. The Battery University has a chart that shows keeping the battery at 40ºC will drop the charge level to 65% after a year. But, for the laptops I have used, when I have removed a fully charged battery from a running laptop, it feels like it is at room temperature. There will still be some loss of life, but not as dramatic as at higher temperatures.

That's not a particularly useful piece of advice. I know the only time that happens to me (just north of Sydney, Australia) is a couple of days in the middle of winter. Also, I haven't seen this suggestion before. If it is on the Battery University, I can't see it.

Yes, heat is bad.

I generally agree with this. But, my personal opinion of how to handle a LiIon battery in a laptop is simple: Put it in the laptop and forget about it.

Why?

The efforts you have to go to delay the inevitable death of the battery is to much for the gains seen. And the advantage of having the battery in the laptop far outweighs this loss of life.

 

OK davidfor said it. To other where are you going to get a 0% humidity environment? Also if you leave your notebook plugged in all the time it will stop charging just as it will not undercharge so those points are mute. Their is no problem doing a full discharge if needed as much as you want.

To the question should I plug in and when fully charged should I unplug? That is the absolute worse thing you could do. Even worse than heat. The battery has a limited number of cycles. Say 300 to 500 on notebooks. Those are full discharges. If you discharge to 50% twice? It counts as 1 cycle. If you do fully discharge once it counts as 1 cycle.

This site has a better guide than Batt U, it does get some info from it but goes further. Battery Guide.

 

Just leave the battery installed in your system.
Removing the battery from the system and storing it at 40% charge is all a scam. The reason batteries die is because of heat, or the internal circuitry of the battery, which is coded to kill the battery.
LION battery can last much longer than you think. I have a bunch of batteries of 7 years old which still hold perfect charge today, and they were never removed from my systems.

The only reason you should remove the battery from the system, is if the battery is getting hot from normal operation. I know on my Lenovo, the battery sits in the back, next to the cpu cooling system, so the battery normally heats up even when the system is just running on ac power.
The heat will slowly degrade the cells of the battery, so removing the battery would be beneficial.
However if the battery on your system does not get hot from normal usage, than removing the battery is not going to be detrimental in any way.

The 300-500 cycles of the battery is also BS.
The lifetime of the battery is precoded by the manufacturer, and can be reset by shorting the microcontroller inside of the battery. Dell has been known to do this in their batteries, and after owning a lot of dell batteries, I just simply take the battery apart and reset the chip inside, and the battery is practically new again

K-TRON

 

K-T we have had this conversation before. And with all you say? All I know is from books. So well that says. As in the past I will only remind you as to what was even more upfront in the past. Batteries and blowing up? Consider? Don't know if it applies or not?

 

I can't completely agree with this. Firstly, I have no hassle with the idea that heat is reducing the life of the batteries. The evidence points to it, and it is a reasonable assumption that heat would be bad.

I have worn out several batteries in an couple of old C-series Dells. I used these daily for about an hour on the commute home from work. The "death" wasn't a sudden thing that would happen if there was a programmed number of charge cycles. It was a gradual reduction in the amount of charge held meaning the life went from somewhere over two hours to the point where it was only last ten minutes. The design of the laptops put the battery at the front well away from any heat sources. As I have stated elsewhere, whenever I pulled the fully charged batteries out of the running laptop, they never felt warm. So, they were at room temperature. If Dell was putting cut-off circuits in them, they were putting some clever code in the circuits to hide the fact. The Thinkpad T40 that I had form work for 18 months behaved the same.

Also, looking at the mobiles phones we have had in the house. These also have LiIon cells. Guess what the battery life profile appears over the years looked like? It fit perfectly with the loss of described by the aging and number recharge cycles described on the Battery University site. Again, heat can't be blamed for the first two phones. One was carried in my wifes handbag and the other in my backpack. Neither have been subjected to constant heat sources.

As to old batteries, the only laptop battery I have that is over two years old and still has a decent life, is the only one that has been in a laptop that has been off for most of the last 18 months (it's plugged in but is normally hibernating between occasional uses as DVD player). I have another that is about two years old where the laptop was constantly plugged in (only unplugged to move to a different room). I can't test that batteries life at the moment as the laptop had a "bath" and doesn't want to work any more.

Overall, what I am saying is that my experience matches that described by the Battery University. That is one of the reasons I point to it when discussing laptop batteries (though I generally point to the guide here unless the person wants more details). You say your experience is different. And you make some other claims. Do you have any links to back these up?

David