Calibrating your battery?

[archcommus]

My school told me we should calibrate our laptop batteries once a month, which involve charging it completely, then letting it sit on and drain the battery completely, and finally charge it fully again. They said this 1) makes the battery more accurately predict how much battery time is left, and 2) extends the life of the battery.

This doesn't seem like a very good way to "calibrate" anything. Can any of you attest to the benefits of doing this? Will it actually extend my battery's life?

 

[Hacp]

Won't extend battery life but will help improve battery life prediction. It might extend battery life in that you know exactly when the battery is full or not full, so you get a full charge all the time.

 

[archcommus]

Originally posted by: Hacp
Won't extend battery life but will help improve battery life prediction. It might extend battery life in that you know exactly when the battery is full or not full, so you get a full charge all the time.

Well, I didn't mean extending my battery's life during one session, I meant extending its life over the course of many years, i.e., make it work better for longer. They said our batteries might not last well all four years of school if we don't calibrate monthly.

I'm thinking, how the hell does doing that increase the battery's effectiveness over many years?

 

[eriqesque]

Originally posted by: archcommus

Originally posted by: Hacp
Won't extend battery life but will help improve battery life prediction. It might extend battery life in that you know exactly when the battery is full or not full, so you get a full charge all the time.

Well, I didn't mean extending my battery's life during one session, I meant extending its life over the course of many years, i.e., make it work better for longer. They said our batteries might not last well all four years of school if we don't calibrate monthly.

I'm thinking, how the hell does doing that increase the battery's effectiveness over many years?

It won't
If this is a Li-Ion battery and I assume it is.
Then it will actually harm the battery if you discharge it deeply.
Li-Ion batteries prefer shallow more frequent chargings and dischargings.

 

[archcommus]

According to hp.com, it has a 6-cell high capacity Lithium-Ion (52Wh) battery. So if what you say is true, I'm amazed the school recommends doing this.

 

[archcommus]

Bump for further opinions.

 

[fbrdphreak]

Originally posted by: eriqesque
It won't
If this is a Li-Ion battery and I assume it is.
Then it will actually harm the battery if you discharge it deeply. Actually it doesn't "harm" the battery from what I have read.
Li-Ion batteries prefer shallow more frequent chargings and dischargings. Now this is true. Just keep the battery charged as much as you can for as long as you can. Once or twice a month, you can deep discharge it to "calibrate" the battery, but I wouldn't say it is "necessary."

 

[archcommus]

Differing opinions now. I'll wait for more comments. I need to decide soon if I'm going to do this or not. If it won't extend my battery's effectiveness over four years I really have no care to do this.

 

[eriqesque]

Answers to all your questions

You will definatly loose capcity if you discharge deeply and that's what I meant by harm.
Also though, if discharched to deeply and the voltage drops to low it can harm the saftey circuit

 

[archcommus]

Thanks for the link.

The website says to AVOID full discharges, however it also says to DO a full discharge every 30 charges to improve the accuracy of the battery life indicator.

Hmm...

 

[archcommus]

Oh, the battery's not fully charged until the light goes out? I thought it was fully charged when it went green. Guess I've been unplugging it at around 80-90% charge for a bit now.

 

[archcommus]

Anyone else do this calibration thing with their Li-I batteries?

 

[Mike01]

I wrote a long post a while back on lithium batteries, but I don't know if it's still around.

To sum it up, much of this "knowledge" that's floating around and being distruted by everyone from colleges to battery manufacturers is dead wrong, at least for lithium batteries.

"Calibrating" is something that benefits nickel based batteries (NiCDs and NiMH). I don't know of a single laptop manufacturer that still uses this technology.

If you want, find my old post and give it someone in your college. Of course the odds of those university morons admitting their mistake is the same as me winning the lotto this week, but good luck.

 

[archcommus]

Originally posted by: Mike01
I wrote a long post a while back on lithium batteries, but I don't know if it's still around.

To sum it up, much of this "knowledge" that's floating around and being distruted by everyone from colleges to battery manufacturers is dead wrong, at least for lithium batteries.

"Calibrating" is something that benefits nickel based batteries (NiCDs and NiMH). I don't know of a single laptop manufacturer that still uses this technology.

If you want, find my old post and give it someone in your college. Of course the odds of those university morons admitting their mistake is the same as me winning the lotto this week, but good luck.

Well actually, it is not the recommendation of some college IT staff, it is the recommendation of the professor of the head of the department.

And it did say on the website linked above that calibrating is good to do for Lithium-ion batteries.

So we have some contradictions.

 

[Mike01]

Calibrating is not good for Lithium batteries, absolutely not, no matter what anyone says. Lithium batteries, like all batteries, have a limited cycle life. That is, with each deep discharge cycle, the battery weakens a little. Even nickel based batteries have a limited cycle life and are harmed in the long term by deep discharging, though it will usually yield (with those types of batteries) better short term performance in the form of a higher average voltage (during discharge) and a slight gain in mAh output, especially in higher amp draw applications.

You cannot avoid this, and there is no way to help it...the battery will die no matter what you do. The least you can do, however, is to avoid unnecessary deep discharge cycles.

Calibrating is, however, good for one thing with lithium batteries, and that is the ability of the OS to predict battery life and provide good estimates as to how much time is left.

That may be worth it to you, especially if you have a Best Buy PSP and get a new battery every year. It may not be.

It's up to you.

My knowledge of batteries comes from competive RC 1/10th scale touring car racing, where it is not uncommon to invest several thousand dollars in batteries and chargers and to do extensive research into the performance and limitations of various types of batteries, since a .1 second per lap advantage is enough to win a race.

 

[Mike01]

I just read that link you mentioned. I was familiar with battery university, they have decent general information although some of their more technical info is not correct for some battery types (can't blame them, there's a lot to know).

However, this is what they say about lithium batteries:

Avoid full cycle because of wear. 80% depth-of-discharge recommended. Re- charge more often. Avoid full discharge. Low voltage may cut off safety circuit

I would point this out to your college professor and I suggest you take this as a life lesson. A professor is just a dude that stayed in school longer than most people and is bound to know a good deal about the subject he teaches. His knowldege in other areas is as suspect as yours and mine. If he is a professor of electrical engineering, I suggest you take everything he says with a grain of salt if he told you to deep discharge your lithium batteries once a month. Does he perchance own stock in a battery company?

 

[archcommus]

Yes, BatteryUniversity.com does say:

Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for lithium-ion than one deep one. Recharging a partially charged lithium-ion does not cause harm because there is no memory. (In this respect, lithium-ion differs from nickel-based batteries.) Short battery life in a laptop is mainly cause by heat rather than charge / discharge patterns.

However, below that, it says:

Batteries with fuel gauge (laptops) should be calibrated by applying a deliberate full discharge once every 30 charges. Running the pack down in the equipment does this. If ignored, the fuel gauge will become increasingly less accurate and in some cases cut off the device prematurely.

So I think they're saying to do it monthly but no more frequently than that? I dunno. If the bolded part is true that's definitely good reason to do it.

 

[Mike01]

It all boils down to a choice. What's more important, long battery life or accurate time remaining estimates?

I calibrate my battery once every six months without any problems, which I like to look at as a compromise between battery life and accuracy.

I'm not sure yet, since I have yet to get a new battery under Best Buy's PSP, if you get to keep your old one or not. If not, I may calibrate more frequently since I only need a year of life out of it. If you're stuck with one battery for the life of the notebook, I'd do it less often.

It's up to you. Remember that whenever you run down the battery under normal use until your notebook hibernates, you're "calibrating" it. So unless you hardly use the battery, there is little point in deliberate calibration.

 

[archcommus]

Well, I definitely want this battery to last as long as possible. I've had the laptop for almost two weeks now and just calibrated last night. So perhaps I won't do it again for a long time instead of monthly like they recommend. Thanks for your opinions.

Now, say in my junior year I would like a new battery. Is there any official source for buying them? If not, and if I can't find any on eBay, would I be screwed?

 

[Mike01]

Manufacturers sell replacement batteries. If you take care of yours, it should last for about four years above 70-80% capacity, which is still pretty good.

The worst thing, the absolute worst thing, that you can ever do to a lithium based battery is to leave it alone for a very long time. Worse still is to leave it alone in a discharged state for a very long time. If you do so, it may die, and even if it doesn't, it will be damaged. By long time I mean a month or more. However....leaving it alone in a discharged state for even a few days may be harmfull.

Don't do that, avoid deep discharges and you should be okay.

 

[archcommus]

Well like I said, I deep discharged and recharged to calibrate last night, but I won't do that again for awhile.

HOWEVER, I'm often out of my dorm using the laptop for 3-4 hours at a time. Just now, for example, I was working in a group for a couple hours. My battery got down to 30%. Sometimes that's just going to happen, because I'm using the laptop what it's intended for, work outside of the dorm. Is going down this low on a regular basis okay? How low is considered a "deep discharge"?

 

[Mike01]

A deep discharge is when the battery goes down to under 10%. Different people have different opinions, but that's a general rule.

You brought up a very good point. The laptop battery exists so that you can use it, not so it can preserve itself. Just do the best you can and don't worry about it.

The thing with calibration is, it isn't necessary. It's one thing to abuse the battery in the course of using your laptop, but just to do it for no reason is like rubbing salt in the wound.

It's cool that you care about your equipment and I'm sure everything will be fine. Worst come to worst, you'll fork over 100 bucks for a new battery in a couple of years.

 

[archcommus]

I'll probably just do a calibration every six months or so. Thanks for your help, very appreciated.

 

[Conroy9]

hmm
if a lack of calibration causes the fuel gauge to be off and "cut the device off prematurely", how will you be able to discharge it past that point to recalibrate it?

 

[archcommus]

That is a very good question.