I have a new battery pack for my acer aspire 4750 laptop, it hust a 2 weeks old, actually it is working pretty good.

I use batterycare to check charge level, so while i am charging and it reached 80% I remove the AC, then recharge it again at 40%.(the batterycare will show a pop-up if I reached 80% or 40% of the battery charged level)

But since yesterday i got these problem, the batterycare and the windows battery indicator notifying me that the battery is already full charged, but when I unplug the AC adapter, i can see the batterycare report and windows battery monitor that the charged level my battery is just 78%.

It doesn't even reached the battery care notification for 80% charged level.

Any idea about this?

I will appreciate for any help will come.


Given 2% could be measurement error I would not fix this.

If the problem persists it could be a faulty battery cell. I've had old batteries do this and could not charge above 60-70%.

Just so folk know, many laptops have a battery care option to charge only up to 80%. This extends the battery life span. If the complaint is that it only got to 78% then it's a discussion about how it did get there, stopped charging and when they looked, it was 78%. I see nothing to fret over here.

@rproffitt sorry i think you didnt get it.
hmm the laptop doesnt come with any utilty for the battery like that on Sony Vaio or the features of hp that will not allow you to hit full charge, i just used this batterycare.net application to make notification if the certain level of charge reached.

the problem is when charging, even turning off the laptop the charge LED indicator will tell that battery is fully charged, but if you remove the AC the charged will drop to around 70%. the big fret here is that its just a week since i recieve the battery, and now its giving me an invalid battery charged reading.

Measuring battery level is dicey. Toss in a 2+ year old laptop, old battery and you will never get a good reading. Add a 3rd party app and you are often lost or have disrupted the native charging system. I'd head back to the stock OS, apps and such before my next move.

Looking up that series I think this laptop is 4+ years old. You have a new battery but this model did run hot and as such aged pretty fast. At this old I'd count myself lucky it works this well.

I forgot a thing. Look in your laptop docs and online about how to calibrate the battery. Many models require a calibration run when you put in a battery.

:) yeah your right it is a pretty old laptop. but guest what it is working like a new, it doesn't even get to hot, it has just an average 45C on a very hot day, i can even throw heavy app on it, like running two or more instances of VS and PS at the same time and have a a browser a lot of tabs open, including the dev database server running at the background. i have other boxes here but this i my on the go pc, i just like it beacuse this my first box.

BTW go back to the battery, this is the second battery replacement i bought, and it is ok now, i just completely drain it power twice, and its working normal now. the only downside is that its capactiy losses around 500MAh, so now i can just make it fullcharge to around ~7100MAh, maybe as @rubberman said it has a faulty battery cell.

yeah that is a bad thing to do on Li-ion, but it is recommended to do after 30 cycles or every 3 months. so do you still have a good battery reading.
as qouted from here howtogeek.com

In reality, you likely don’t have to do this that often if you’re not too worried about your laptop’s battery readings being completely precise. However, if you don’t calibrate your battery regularly, you may eventually find your laptop suddenly dying on you when you’re using it — without any prior warnings. When this happens, it’s definitely time to calibrate the battery.

The key to calibration is allowing the battery to run from 100% to almost empty and then charging it all the way up to 100% again, which may not happen in normal use.

I'll disagree. Battery calibration is not a single procedure that fits all machines. However since battery makers and others stand to gain from such, we can assure ourselves of more sales over time.

-> At the office, over one hundred laptops and I think we did a battery calibration once last year. It's a rare thing but imagine folk that can't stand the battery reading being off by a percent point. They'll wear out the 300 cycle battery calibrating.

In the term of the manufacturer, yeah you right, that is good for their business, but what we can do? but i think it still good to calibrate at least if you feel that the reading is not correct, rather than if you are in the presentation and you thought that you still have enough battery juice, but suddenly your laptop shutoff in the middle of the session, that could be frustrating.

And not just high number of battery cycle make the battery died, but one the biggest factor is the heat, that will degrade you battery life very fast.

I also have HP machine here, and the battery charging was controlled by the laptop very carefully, it doesnt even allow to fully charged the battery, even you plug-in the AC overnight it will not reach full charged, and until now it is still kicking.

even you disagree about the calibration, but still you did it once last year.

Sorry but I was unclear. It was a new battery install and while it charged to 100% it seemed a little short on time so we gave the battery calibration a go. Batteries here have dropped in price so rather than the old 150USD it was, these are now well under 99USD for maker issued batteries. There are cheaps that are less but for us the liability would be unacceptble as you can guess.