some say tethered laptop breaks battery; others say overcharging is impossible - what's the SD?

I have seen statements to the effect that keeping a laptop with a full battery plugged into the grid damages the battery here at the forum. I am also seeing claims online that “overcharging” is impossible thanks to latest technical improvements in the charger gadget, e.g. here http://answers.yahoo.com/question/index?qid=20101222230406AASINiA

Are both of these statements true at the same time? Is the process of damaging the tethered battery essentially separate and distinct from the process of damaging battery via overcharging?

If they improved the charger to deal with overcharging, why don’t they similarly improve it to deal with tethered full battery? E.g. why doesn’t the charger disconnect a full battery from the grid completely?

To my knowledge, it is not possible to overcharge a properly functioning modern laptop battery. They all have a built-in charge controller that prevents it from being overcharged and explode. I can see that in action on my laptop: If I check the Windows Power Meter, I can see that a fully charged battery will be allowed to naturally ‘leak’ over time and will not be constantly charged. The charger will automatically kicks in once the charge drops to somewhere a little over 90%.

Dell laptops have a reputation for over heating the battery pack. That can shorten it’s lifespan. Some recommend leaving the battery pack out unless it’s needed.

I tried that for awhile. The problem is that crappy plug in cord. It’s doesn’t take much for it to come half way out and crash the laptop. I reluctantly started keeping the battery pack in. Even though 90% of the time I’m running it plugged into electricity.

Eventually, that battery pack pretty much died. So what I do is keep my new battery pack charged and in a drawer. The old battery pack has just enough juice to survive a few minutes if the laptop comes unplugged. That way I get the best of both worlds.

This has been covered before in one of your other threads.
The problem is this: Fully charged Lithium batteries have a shorter storage life than partially charged ones. It has nothing to do with “overcharging.” The current state of the art of battery technology has no solution to this problem (although there are a new crop of batteries which are about twice as good with respect to charging cycles). That’s just the way it is.

ok, so why doesn’t the charger automatically stop charging slightly below the “fully charged” level? Let’s say this could be regulated programmatically - if I really care about the last minute of work, the OS will direct the battery to be fully charged, but if I don’t they should be partially charged by default.

That makes sense. Most laptops have all sorts of user-settable battery options. One could be the “I rarely unplug my laptop so keep it at the optimal level for battery life” setting.

Geeze - this has been covered, too!

It’s because nobody (except possibly you) want’s to micro-mange their battery charging routine like this. They want a fully-charged battery. Period.

does nobody (except possibly me) want to have their battery remain functional without replacement rather than lose an hour worth of charge capacity after a year of use? Period?

What planet are you from?
On my planet (Earth) every product that the dominant technologically-advanced species (Humans) designs involves price/performance/usability tradeoffs. In this specific case, the designers have determined that the vast, vast majority of their users would rather trade 50% of the initial battery life* at the end of three years* than have only 50% of battery life for 5 years.

So, yes, most people would rather have a laptop that gives 5 hours of battery life for 1 year and then 4, 3, 2 hours for years 2, 3, 4 rather than one that gives 2.5 hours of battery life for 5 years. Period.

Since this thread is about tethered use, just take than damn battery out if you are so concerned about it’s usable life.

I’ve watched you start a number of threads about trying to solve non-problems. If you think your idea is so great -** DO IT**. Maybe there’s a huge pent-up demand for battery charge controllers for OCD users. Maybe.

I’d use Tim R. Mortiss’s “I rarely unplug my laptop so keep it at the optimal level for battery life” setting if it were available.

I can just imagine the customer-service calls such a setting would inspire:

User: This laptop sucks!
CS: I’m sorry, sir - could you be more specific?
User: Yeah - you advertised 5 hours of battery life, but I only got 1 hour yesterday! My laptop went dead in the middle of an important presentation that I was unexpectedly called to, and I lost a big job because of it! I’m going to sue you guys for false advertising!
CS: I’m very sorry about that, sir. Did you happen to have “Optimize battery life” checked?
User: Of course.
CS: Well, that’s the issue - that setting only charges the battery to 25% to increase it’s useful life by 40%.
User: What a stupid feature - I want 5 hour battery life AND 5 years between battery replacements.
CS: I’m sorry sir, but that’s not possible with current technology.
User: That’s not my problem, and I’m still going to sue you!

My Dell battery is toast after only one year of mostly plugged-in use. That’s complete crap.

It’s a Dell, Dude(ette).

Look, it’s either “no one’s going to use it”, or “they’re going to get a bunch of complaints about it”. You can’t have both.

OK, sorry about the hyperbole - I’ll amend my statement to: “Almost no-one will use it, and the ones who do will regret their decision the first time they need their laptop for an unexpected off-grid trip, and then will turn it off.”
How’s that?

My battery on my dell didn’t die after a year or so, my power cord did, this is apparently a big problem. If your charging light on your dell keeps coming on and going off very fast, it’s most likely a power cord problem.

My Asus is currently at 97% charged but not charging, I rarely see it 100% charged, it winds down to 90% or so then charges back up. Its a dinosaur, almost 2 years old, but it’s battery still works fine on those rare occasions when the power goes out that it’s not drawing power, it has never been unplugged.

Much better. I think your more reasonable statement is still incorrect, though. I just asked my wife if she’d use a setting that kept her battery charged to 60 percent if it would increase the battery lifetime, and she said “Yes, definitely.” I smell a poll…

I had this problem on my Compaq (the cord from the brick to the laptop, not the wall cord) after two or three years, shorting out the brick. Bought an off-brand replacement, and that even-lower-quality cord wore out in under a year. I was able to wire the old cord to the new brick, and now I’m really careful about letting that cord bend.

ok, now, is the number 50% of full charge used by beowulf a random one or is it actually accurate? Does anybody know just what maximum percentage of the full charge can be used to avoid the lifespan reduction of a “full” battery?

If the charge to lifespan relationship is actually described by a complex nonlinear function, then our ignorance of it as well as of its possible simpler rule-of-thumb approximations could be fought as well :slight_smile:

I mostly use my Asus laptop as a work machine. I rarely take it off the desk. It has been powered on pretty much since I got it, over two years ago now. It’s nearly always plugged in, and when I do unplug it to travel, I generally sleep it (not hibernate). I see no perceptible change in battery life since I got it.

Read the link I posted in your previous thread.