General Question

Bluefreedom's avatar

I have a couple of questions about my new laptop computer regarding charging the battery.

Asked by Bluefreedom (22877 points ) September 15th, 2009

I’m trying to find a balance of when I have to use my laptop with the battery and using the AC adapter. I’ve looked over the users guide and it states a couple of things that look ambiguous to me:

“Once the battery is charged for the first time, avoid leaving the computer plugged in and turned off for more than a few hours at a time. Continuing to charge a fully charged battery can damage the battery.”

“To ensure that the battery maintains its maximum capacity, operate the computer on battery power at least once a month. The Lithium-Ion battery has no memory effect so it is not necessary to let the battery fully discharge each time. If the computer is continuously operated on AC power for an extended period (more than a month), the battery may fail to retain a charge. This may shorten the life of the battery, and may cause the battery meter to be inaccurate.”

So, what I’m getting from this is, I can operate my computer continuously on AC power as long as I let the battery discharge once a month even though the first paragraph says ‘continuing to charge a fully charged battery can damage the battery’. Does the AC adapter automatically stop charging the battery once it is fully recharged? Are there other laptop users out there that operate their laptops exclusively on AC power?

Any input, knowledge, or experience anyone might have with these queries would be greatly appreciated and thanks in advance for your answers. Sorry the question was so long.

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6 Answers

wenn's avatar

charge when the battery is flat. if the battery is full leaving it plugged in to the charger will damage the battery and youll end up buying a new battery.

attach the AC charger when there is need for it.

OpryLeigh's avatar

I can speak from experience on this. The battery power on my laptop runs out very quickly when not plugged in to the mains nowadays because if I could I would always have it plugged in even though it was fully charged. Now, until I get a new battery (or laptop) I have no choice but to keep it plugged in if I want to use it for anymore than an hour!

LaughingWolf's avatar

It depends on what kind of battery you have, both my Dell and my MacBook don’t mind being plugged in for days at a time.

But your battery can be damaged by leaving it plugged into the wall when it’s fully charged (because the current from the wall is not being blocked and continues to flood the battery). But since most laptops only take one kind of battery, you are likely stuck with it for now.

Bluefreedom's avatar

A little more information from me. I currently go on battery power when it is at 100% and then use my laptop until the warning bell rings and notifies me that I’m at 10% power and notifies me to start recharging again. I charge to 100% and start the process again. It gets a little old after a while and that is why I was curious if I could stay on AC power for longer periods and just discharge my battery once a month like the user manual said in my question’s details above.

simpleD's avatar

According to the instructions you quoted, it is only dangerous to leave the computer plugged in and charging while the computer is off. Perhaps if you leave it plugged in while the computer is being used, or when it is sleeping, there is no danger.

Different computers have different power management configurations. MacBooks, and some Dells (according to @LaughingWolf) will stop sending power to a fully charged battery, so you can leave it plugged in as long as you want. Still, it is advised to cycle the battery from full to empty at least once a month.

Bluefreedom's avatar

@simpleD. That’s what I was thinking also – okay to leave it plugged in during operation. I have a Toshiba Satellite laptop and I have a feeling that my adapter stops sending power to my battery after it is completely charged. What I found out was, while charging the battery, the AC adapter is moderately warm to the touch but when the battery reaches a full charge at 100%, the AC adapter goes cool to the touch leading me to think it isn’t charging the battery anymore. Could that be an accurate assesment maybe?

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