New Laptop Battery

Hi guys, I just recently purchased a HP dv9640us laptop. I heard that if you run the battery dead several times in a row and recharge it, it will increase the lifespan of the battery. Is this true?
Thanks,
-BEaver 2

Nup. Perhaps that advice dates back to really old NiMH laptop batteries.

Did that with my IBM ThinkPad. Ran the batteries down several times and now it won't hold a charge more than 1/2 hour or so. Best to remove lap top batteries when you are using it like a PC. Install battery when you are writing up something important so you don't lose it if power goes out.

Bill

A lot of battery monitoring hardware/software needs to know what the bottom point is before it can give you any meaningful measure of remaining capacity for your usage. I suspect this is why most manufacturers recommend a deep discharge early in the pack's life.

This is speculation by the way. But most cells / packs are not intended to be run flat in other usage and laptops are particularly hard on their batteries anyway. I did once dramatically improve the life of a laptop pack by running it dead, it went from not being able to boot the machine to being able to boot the machine but not long enough to shut it down again. About a 200% improvement but still useless.

dulridge has the skinny on this. Since you can't measure the voltage of a LiIon cell and figure out how much power is in it, the chips in the batteries actually measure power in vs out! So in order to calibrate the off point you have to run them all the way till the computer goes to sleep. Apple specifically explains this for their batteries, but other companies work the same way.

So initially, and once in a while as the batteries capacity declines over use and time you have to let it go all the way down to recalibrate the counter that knows how much power is left.

But this doesn't really affect how much power the LiIon will hold, only tells the computer to get it's estimates more accurate. And when they say "deep discharge" it is NOT a deep discharge as far as the battery is concerned. At least not in the higher quality machines Some cheap laptops really dont keep track of the battery very well and running them all the way down can reach levels for the battery, at least in my limited experience and anecdote hunting. But a machine that properly manages it's battery will not allow a deep discharge but will put the computer to sleep before it begins to reach a point that will damage the battery.

My ThinkPad pack is rated 14.4V 4AH. Run time was excellent after purchasing it. I let it run down too much, I think. Now within 10 minutes the % box shows 60% or so, and dropping. Anyway to bring this pack back?

I just removed pack and tested it. Reads 16.50 volts, so 8.25 X2, I replaced battery pack leaving AC attached and box reads 90%. Removed cord quilckly and box reads 100%. Now letting in run on battery only, Two minutes= 87%. 15min= 45%. 23min= 14% and warning. Pulled battery pack and read voltage quickly =15.87V. Let rest and it now reads 16.08V. Well, it appears my little % box is reading wrong and I have plenty of life left in my pack. How to correct my laptops battery info?

Bill

Thanks for the help guys.
Bullzbill, I was just this article from from Battery University.
I believe your laptop is suffereing from a digital memory problem.

Although lithium-ion is memory-free in terms of performance deterioration, batteries with fuel gauges exhibit what engineers refer to as "digital memory". Here is the reason: Short discharges with subsequent recharges do not provide the periodic calibration needed to synchronize the fuel gauge with the battery's state-of-charge. A deliberate full discharge and recharge every 30 charges corrects this problem. Letting the battery run down to the cut-off point in the equipment will do this. If ignored, the fuel gauge will become increasingly less accurate. (Read more in 'Choosing the right battery for portable computing', Part Two.)

Click to expand...

If you let your laptop run down completely, it should correct this problem. When I say run down completely, I mean that you should let computer keep running despite when its a 3% or 5%. Most PCs automatically turn off at that point, therefore you have to go to
Control Panel>Power Options> Advance tab
Here you should be able to stop the computer from automatically turning off. When I did this, my older laptop ran for around 20 minutes on 0%!
Hope that helps,
-Beaver_2
P.S. Make sure to have all your work saved on your laptop before running it down so you don't lose anything.

Hello Bill,

While agree with "the Beaver," (Sorry Beaver 2, but this just reminded me of the old TV show Leave It To Beaver. Please do not be offended by this offhanded comment...) it could also be that your pack has a bad cell in it.

Your total voltage off the charger was 16.5 volts. You have 4 cells in series, and they could have voltages of 4.2, 4.2, 4.2, and 3.9 volts. Obviously the 3.9 volt cell is not doing well, and could be bringing the whole pack down.

It is too bad you can't conveniently open the pack up to measure the individual cell voltages...

Try the digital reset first, but if that is not successful, you may want to consider a new pack.

Tom

Beaver_2 said:

Thanks for the help guys.
Bullzbill, I was just this article from from Battery University.
I believe your laptop is suffereing from a digital memory problem.



If you let your laptop run down completely, it should correct this problem. When I say run down completely, I mean that you should let computer keep running despite when its a 3% or 5%. Most PCs automatically turn off at that point, therefore you have to go to
Control Panel>Power Options> Advance tab
Here you should be able to stop the computer from automatically turning off. When I did this, my older laptop ran for around 20 minutes on 0%!
Hope that helps,
-Beaver_2
P.S. Make sure to have all your work saved on your laptop before running it down so you don't lose anything.

Click to expand...

Exactly what I am doing. I let it run, batttery only, even when warning came on and meter said 5% (one minute remaining). It ran for one hour at 5%, I upped cpu's and it dropped to 0%, but still running. I took off all turn off controls, including hibernating and it is still running, almost two hours since earlier post. I am waiting for protection circuit to cut it off. Then I will recharge.

Bill

E

I ran many times my ThinkPad Li-Ion battery pack until it shut down (0%) with no apparent ill effect. My pack is over 2 years old and has around 130 cycles If I calculate the ratio real capacity/design capacity, it is now at 78% of the original capacity. I don't consider this that bad!

Bullzeyebill said:

Exactly what I am doing. I let it run, batttery only, even when warning came on and meter said 5% (one minute remaining). It ran for one hour at 5%, I upped cpu's and it dropped to 0%, but still running. I took off all turn off controls, including hibernating and it is still running, almost two hours since earlier post. I am waiting for protection circuit to cut it off. Then I will recharge.

Bill

E

Click to expand...

I ran the battery down till it shut the laptop down, a total of 2 1/2 hours, two hours with scale saying 5%, then 0%. I recharged and now up to 99% but not going higher. I will run it for awhile without cord and see if it drops like a rock, as before. Running 15 minutes with battery pack and % scale says 26% and 3 minutes remaining. Still lying to me. Now 11% and Low Battery warning. How to reset remaining battery time? As I stated, I have run the battery down till protection circuit shut down computer and recharged back to 99%.

Bill

Bullzeyebill said:

I ran the battery down till it shut the laptop down, a total of 2 1/2 hours, two hours with scale saying 5%, then 0%. I recharged and now up to 99% but not going higher. I will run it for awhile without cord and see if it drops like a rock, as before. Running 15 minutes with battery pack and % scale says 26% and 3 minutes remaining. Still lying to me. Now 11% and Low Battery warning. How to reset remaining battery time? As I stated, I have run the battery down till protection circuit shut down computer and recharged back to 99%.

Bill

Click to expand...

Maybe HP have a battery reset utility available somewhere on their website. Failing that, I'd try to reset the CMOS which may well reset the "fuel gauge". How you do this, varies from laptop to laptop. I know that Apple do provide just such a program for theirs. The fundamental problem is that voltage isn't a hugely reliable guide to the state of lithium battery packs as the cells age, though this shouldn't apply to new packs.

For a "fuel gauge" to do any good, it must contain some non-volatile memory and this is not terribly likely to be stored in the battery pack, though it could be, hence my recommendation to reset the CMOS.

Bullzeyebill said:

I just removed pack and tested it. Reads 16.50 volts, so 8.25 X2, I replaced battery pack leaving AC attached and box reads 90%. Removed cord quilckly and box reads 100%. Now letting in run on battery only, Two minutes= 87%. 15min= 45%. 23min= 14% and warning. Pulled battery pack and read voltage quickly =15.87V. Let rest and it now reads 16.08V. Well, it appears my little % box is reading wrong and I have plenty of life left in my pack. How to correct my laptops battery info?

Bill

Click to expand...

I've also noticed that my laptop's life indicator drops quickly, and can sit on 0% or something very low for quite a while. But laptop batteries do eventually die, and if that's the case you measuring a non-loaded battery won't give accurate results.

I am getting well over two hours with my battery pack, but fuel gauge drops quickly. Non loaded LiIons are pretty good indicator of remaining capacity.

Bill

dulridge said:

Maybe HP have a battery reset utility available somewhere on their website. Failing that, I'd try to reset the CMOS which may well reset the "fuel gauge". How you do this, varies from laptop to laptop. I know that Apple do provide just such a program for theirs. The fundamental problem is that voltage isn't a hugely reliable guide to the state of lithium battery packs as the cells age, though this shouldn't apply to new packs.

For a "fuel gauge" to do any good, it must contain some non-volatile memory and this is not terribly likely to be stored in the battery pack, though it could be, hence my recommendation to reset the CMOS.

Click to expand...

How to reset CMOS? I discharged to cutoff and fully recharged. Fuel gauge still not woriking.

Bill

I'm not actually suggesting you do this, because i have no idea what the internals are like in the particular battery that you're having trouble with.

In the not too distant past there was a fix to reboot the chip on some Apple batteries. You actually had to short out the battery for a second. This caused the internal protection of the pack to kick in and completely disconnect the battery for a moment. this also disconnected power from the built in chip resetting it.

There are more than 2 pins on a computer battery, some are even serial data for the little chip to talk to the computer. If you short the wrong ones the battery is toast.

This assumes that there even iS any protection inside the pack like that. I only know for sure about the specific brand of Mac batteries.

This assumes that the protection is upstream of the chip, which i have no idea.

This assumes that the protection is working, if it has failed then all you're doing is making a very expensive and messy trip to the emergency room.

Before experimenting with this, I'd have a good search on the internet and see if anyone else has successfully used this technique on your particular battery. If the battery is just defective, or has been misused by the computer and charger there is nothing that can bring back capacity that is really gone. All this assumes that it's just the counter that is wrong and the battery itself is still good. This might not be the case. And if the battery is defective, perhaps was shipped with counterfeit or just cheap parts, it might not have working internal protections. There have been numerous pictures posted around here of counterfeit cells where the protection board was never populated with components! Or even was just completely missing. This might have been the case with your battery if it started to degrade so quickly, perhaps the protection is letting it discharge way to far, or perhaps it was just overheated in shipping or something. but those things might make it dangerous to perform the short out reset.

James S, thanks. I am now leaving the battery out, except when I need to make important entries, or need it away from the house. I am checking the resting voltage, so am monitoring closely. Battery seems ok, just counter is all screwed up. I got the ThinkPad R40 from the factory as a used item. The battery counter (fuel gauge) worked fine at first. I used the laptop llike a PC at home keeping the battery in all the time, using the battery as primary power then shifting to plug when I got the low battery warning signs. Somehow, overtime, the counter got fouled up, going from almost 3 hours to 20 minutes warning and % drop. I will use this battery till my external voltage checks really show the battery to be losing capacity.

Are there any good after market packs that are as good as OEM batteries?

Bill