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Does power drop when charging a laptop battery after the battery is full? Answered

 I want to know if the power going to the laptop drops after the battery is at a full charge.  I understand that power will still be going to the laptop but perhaps there is a slight drop in power because the load has decreased?  This is what I want to do with this: I want to make a device that will shut off power to the laptop when the battery is full but turn on power to the laptop whenever the laptop is on.  The latter part (turning on power to the laptop when laptop is on) should be easy, I think, by just having a USB cable running to the device actively telling it the laptop is on.  Anyways, the question I want answered is at the top but if you have any suggestions for this project I'd love to hear them.  Thanks



Best Answer 8 years ago

Depends on the charger.  A cheap charger will just go on continually pumping out the power whether the battery is full or not.  Batteries should not be left on these continually.

A better charger monitors the battery and turns off after the battery has hit full charge.  There are some in this catagory that instead of turning off will just go on slow or trickle charge.  These can be left on continually.

The best kind monitor the battery and turns off after the battery is full but continues on monitoring the battery and if it drops below a certain point turns back on again to do the cycle again.

So you'll have to figure out what kind of charger you have.

P.S. If you're building a charger for lithium batteries, go to youtube.com and search "lithium fire" before you implement your device.

 do you have a link for an example of the 3rd/last type of charger you stated?  I currently have a hp smart ac  adapterwww.shopping.hp.com/store/product/product_detail/VE025AA%2523ABA/1
which has a built in surge protector.  I have never heard of such an adapter.  If I can buy one that would be even easier than trying to make one can you give me an example or even better one that would work for my laptop?

I do not have a link  for the charger.

But I have an HP laptop and have for about 2 years left the charger plugged in all the time and have not damaged my battery yet, so the HP charger must bet ok for that.

* Through your operating system you can specify power management features and functions – optimize these features and areas to expand notebook battery run-time. * New laptop battery needs breaking in: fully charge the laptop battery, discharge it down to 20% remaining and then fully charge it again, repeat 3-4 times to break-in the notebook battery and get it to charge to its maximum * Regularly clean notebook battery contacts to maintain good and clean contacts between the notebook battery and laptop. A cotton swab and alcohol can be used to clean laptop battery contacts * Exercise the notebook battery, at the minimum you should use the laptop battery once at least every couple weeks. If you haven’t used your laptop battery in sometime then use the break-in procedures again as described above * Properly store your laptop battery if you will not be using it for an extended period of time (one month or longer) in a cool, dry and clean place after fully charging the laptop battery. From: http://www.laptop-battery.sg/

I'm not an electonics expert but this MAY work. Most computers have a light that turns on/off when your laptop is fully charged. if you placed a wire to that led you would have a signal telling if your battery is full (Electricity dissapearing/appearing)