This forum is in permanent archive mode. Our new active community can be found here.

Now I am scared

edited June 2008 in Technology
I've been trying to find a battery calibration mode for my notebook computer and I finally found it.

In the past my notebook PCs always had an area in the BIOS for battery calibration and testing. The one I have now does not.

So, what does the manufacturer have to say about calibrating the battery in my notebook?

Step 1: Fully charge battery.
Step 2: Turn off all power saving features.
Step 3: Leave computer on battery power until it runs out of juice.
Step 4: Plug it in and recharge the battery completely.

Um... Yeah... My computer manufacturer wants you to just run the computer out of juice to calibrate the battery. I don't know what to say. I'm used to calibration routines that allow me to watch the battery charge and discharge while telling me the amount of juice the cells can hold. The laptop I gave my daughter had a very nice system that would tell you exactly how many mah of juice the thing would hold. This one does not even tell me that! Yeah, I got what I paid for.

Comments

  • That's the way I know for keeping up a battery's health. Doesn't it seem logical to completely empty and fully recharge it?
  • The complete discharge/recharge cycle for calibration is necessary due to the inherent properties of Lithium-ion battery technology.
  • The complete discharge/recharge cycle for calibration is necessary due to the inherent properties of Lithium-ion battery technology.
    I thought that Lion didn't need that? I thought only NMH and NiCad needed those discharge cycles?
  • edited June 2008
    The complete discharge/recharge cycle for calibration is necessary due to the inherent properties of Lithium-ion battery technology.
    I thought that Lion didn't need that? I thought only NMH and NiCad needed those discharge cycles?
    Careful. You're talking about a guy who is so smart that he knows water can boil on Mars.

    Lion batteries have no memory effect. It is better to partially charge them versus a full charge.

    My understanding is that these periodic calibration tests have more to do with the laptop recognizing how the battery is doing so it can give you an accurate assessment as to how much power remains in the battery at any given time.
    Post edited by Kilarney on
  • Um, I clearly said for calibration. For getting the maximum life out of the battery, it is a different story.
  • due to the inherent properties of Lithium-ion battery technology.
    For callibration, isn't this true for pretty much any type of battery?
  • For callibration, isn't this true for pretty much any type of battery?
    No. For normal everyday Alkaline batteries, AA, AAA, etc. you can figure out how much juice they have left with a simple battery tester.
  • No. For normal everyday Alkaline batteries, AA, AAA, etc. you can figure out how much juice they have left with a simple battery tester.
    Your smartness remains.
  • I guess I should comment on this one, considering that I write the code that goes into some of those monitoring chips that track the battery charge ;)
    No. For normal everyday Alkaline batteries, AA, AAA, etc. you can figure out how much juice they have left with a simple battery tester.
    This is actually true about Lithium as well, and some of the chips even make use of this. The problem here is that you only have part of the picture. Testing voltage to determine the capacity in the battery only works with an open circuit. Once you put the battery under load, the voltage will drop proportionally to the load. This is why in things like your cell phone, or your Nintendo DS you may see the battery dip low in a call (or go orange when you play a GBA game), but then go back up/turn green later. There are battery chips out there that "calibrate" based on this open circuit voltage when you remove the load from the pack. They however are more expensive and so are not in most consumer laptops.
    Lion batteries have no memory effect. It isbetter to partially charge themversus a full charge.
    Yes, it is better for the lifetime of laptop batteries to not discharge them fully. Since the laptop software uses the information provided by the battery chip to know time remaining and when to shut down. In most consumer laptops, this chip keeps track of the battery charge by monitoring the charge going in and the charge going out (and estimating the "self discharge" of the battery over time). The problem here is that the chips need two points of reference in order to know the true capacity of the battery over time. The battery has to be discharged from full to empty (based on a voltage check) to update the capacity available in the battery. So while it is technically bad to discharge lithium ion batteries fully, it is needed on occasion to learn the capacity in the pack as the cells age. It is also bad for Lithium batteries to be on the charger constantly. The way most packs are programmed by the manufacturer, it will recharge the battery to full after it self discharges to around 95%. If you leave your laptop plugged in, these shallow cycles damage the cells. Lithium cells are best stored around 50% charged.

    My ideal laptop battery controller would actually refuse to re-charge your battery until it drops below 50%, so I can run it plugged in most of the time, and do some activities on battery without causing a lot of extra charge cycles. I would also want a button to press to trigger a charge, so when I know I am going to be out and about for a long time I push the button to trigger a full charge without waiting for the 50% mark. Of course they will never do this, it is way to confusing for most users.
  • If you leave your laptop plugged in, these shallow cycles damage the cells. Lithium cells are best stored around 50% charged.
    0.0 Maybe this is why I've had two battery pack die on my laptop recently. I always leave it on my dock and rarely use battery power...
  • I just took both batteries out of my laptop while it was running, but I left it plugged into the AC adapter. I'm posting this forum post from it right now. Sure, if I plug it into the wall, and the batteries are not fully charged, it will recharge them. However, it won't continuously discharge and recharge the batteries if I leave it plugged into the wall when they are already full, it will just leave the batteries alone and use the AC directly for any power it needs, unless the AC gets unplugged. However, you are correct that if you take your laptop, use it a bit on battery, then plug it in, then unplug it, the constant recharging phenomena will occur.

    Also, so people know, we tried to get James on the show to talk about batteries, but he denied us.
  • Good information in this post. My laptop runs almost 24/7 so it is almost always plugged in. It is my main computer and I have a small "laptop desk" that it sits on.

    I would unplug it once it completes charging and then run it on battery but then I would also want to have a spare battery with a full charge in it in case I have to go somewhere. I would be very pissed if I got up to go somewhere and my battery was under 50% charge. Why can't they build in a software setting where you can tell the computer not to charge the battery (even if plugged in) unless it hits a certain threshold?
  • A simple way to get around the shallow charge problem is already in use in most laptops. Instead of starting to charge when the battery dips below 100%, the battery instead begins charging when the battery is below 90-95%. While it doesn't eliminate shallow charging altogether, it drastically cuts the number of shallow charges performed, extending the life of the battery by an order of magnitude past what an old laptop would be able to manage.
    Why can't they build in a software setting where you can tell the computer not to charge the battery (even if plugged in) unless it hits a certain threshold?
    This setting is almost always set on a hardware level, simply because otherwise you'd need to boot your laptop to charge it. New HP laptops actually have an option to turn this feature off in BIOS, but I haven't seen anything that lets you change the value yet.
  • I just took both batteries out of my laptop while it was running, but I left it plugged into the AC adapter. I'm posting this forum post from it right now. Sure, if I plug it into the wall, and the batteries are not fully charged, it will recharge them. However, it won't continuously discharge and recharge the batteries if I leave it plugged into the wall when they are already full, it will just leave the batteries alone and use the AC directly for any power it needs, unless the AC gets unplugged.
    Correct, the laptop is not using the battery. The cycles I was referring to are caused by a combination of battery self discharge and the load of the battery monitoring chip.
    A simple way to get around the shallow charge problem is already in use in most laptops. Instead of starting to charge when the battery dips below 100%, the battery instead begins charging when the battery is below 90-95%. While it doesn't eliminate shallow charging altogether, it drastically cuts the number of shallow charges performed, extending the life of the battery by an order of magnitude past what an old laptop would be able to manage.
    It is exactly these short cycles that I am talking about. Charging lithium batteries to 100% is not really good for the chemistry either as far as longevity is concerned.

    As usual, the behavior of the battery is programmed based on the best interests of the marketing folk, not the best interest of the battery chemistry.
Sign In or Register to comment.