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I'm using my laptop at home with battery removed and only connected to the AC power. However I'm lacking the mobility as my power cord is kinda short. Is it safe from electrical point of view to plug in the battery while the laptop is connected to AC and disconnect the AC power afterwards?

What about the opposite side of the question - is it safe (or what the damage could be) if you work on battery, plug in the AC and unplug the battery?

If there are differents for different models of laptops, I'm asking about IBM Lenovo T60. Is there such thing as a 'hot-plug battery'?

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See this question for the drawback of working without the battery, – FredrikD Aug 9 '12 at 8:25
up vote 11 down vote accepted

Most laptops have hot-plug batteries, which allows you to go to line power for a few moments so that you can swap out your nearly-dead battery for your fully-charged spare. I see Lenovos as being no exception to this.

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Just in addition to this, you can use AC as your main power on the laptop as well, not just for a few moments, although the OP has already figured that out :). – Azz Sep 27 '10 at 6:08
@Azz: That depends on the laptop. Many Thinkpads, for example, cannot do this because they cannot supply the surge of power the CPU needs when it comes out of a halt state without the battery. – David Schwartz Oct 8 '11 at 6:07

I have a lenovo e545 that would not charge while plugged in. I looked around for every possible remedy for this and nothing worked. What did work was turning it on without that battery and then slamming the battery in. Now it is charging. HTH

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Sounds like either your AC adapter or the charging circuit in the laptop is defective. – Jamie Hanrahan Apr 30 '15 at 8:43

Personally I wouldn't risk it. If, as you say, the power cord is short there's a good chance it'll come out during the operation anyway.

Laptop batteries are designed to be left in whilst the unit is on mains power anyway so you're not really gaining anything by removing the battery unless you're not going to be using the battery for an extended period.

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Removing the battery may lengthen its life. If you remove it after decharging, then it will last longer than if it is always fully charged. – petersohn Apr 16 '10 at 14:54
@petersohn - I've updated the last sentence to clarify it (hopefully) – ChrisF Apr 16 '10 at 15:20
Li-Ion batteries have a lifespan of about 1-2k cycles. I know it is probably not worth it, but I'm trying to save a few cycles. And I do really need a battery at weekends when I'm travelling. – Ivan Petrushev Apr 16 '10 at 16:47
Li-Ion batteries care less about cycles than simply about time and temperature. If you have a T60, then temperature isn't a problem since the battery is away from everything that generates heat on purpose (I see the same with my R60 and my Dell laptop). That being said, I have never seen a laptop battery die because of fiddling with it while the power cord was plugged in. I highly doubt there will be any effect at all; there's pretty much of electronics in the way to ensure various things. – Joey Apr 16 '10 at 17:01
Can confirm this works with a Lenovo T540p just Googled this up to be sure before I slapped the battery in. – Arthur Kay Aug 10 '15 at 17:13

Insofar as I have successfully tried on different models of a Dell, an Acer and a Gateway, both old (down to 2007), and brand new - I haven't noticed any problem with hot-swapping batteries.

Just a note, even though I'm guilty for doing it I don't know if there's any use to take out a battery after it has been discharged to save cycles since I've read that only applies to older batteries; therefore, you will only want to hot-swap when you're actually hot-swapping 2 batteries and not just taking one out.

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No, you can't change batteries while the laptop is plugged in. Follow these steps:

  1. Turn the laptop off or put it in Hibernate mode
  2. Unplug the AC adapter from the wall
  3. Unplug the AC adapter from the computer
  4. Unplug any other wires connected to the laptop
  5. Remove or connect your battery

If you don't follow these steps, you could be injured.

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" could be injured." NO, YOU CAN'T. This "answer" assumes that 24 volts or less (which is the maximum voltage on exposed contacts on any laptop's battery terminals, power adapter output, or any other connector on a laptop) can be considered dangerous. This is flatly WRONG. 30 volts is considered the upper limit for "low voltage" (with which accidental contact is not a problem and therefore need not be guarded against) - see . – Jamie Hanrahan May 3 '15 at 20:55
This "answer" also proposes a number of steps that would be completely unnecessary even if the charger output, or the voltage at the battery terminals, was hazardous. It's ridiculous. It's like saying you should turn a lamp's switch off, AND pull the breaker on the circuit, as well as unplugging it from the wall before changing the bulb. I can't decide if the writer was honestly overly fearful of electric shock or was having fun with us, but either way, this "answer" should be ignored with extreme prejudice. – Jamie Hanrahan May 3 '15 at 20:58

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