Is it safe to operate a laptop without battery?
Andrew Mclaughlin 
I know it's 'unsafe' in terms of data loss but I noticed motherboards still have some of their circuits on power when they are plugged in [e.g. a circuit that must wait for power-on signals is certainly one of them]. Hence, I wondered if it would increase the life of the laptop if the battery was simply off. Let alone that may also increase battery life, but that's the least of my concerns.
Notice the main point is to plug it off on hibernate and have no power source whatsoever for the duration of being off (apart from the clock battery). (i.e. saving having to plug off the battery every time)
110 Answers
Longevity of a notebook has many factors, but power through motherboard circuitry while sleeping/hibernating would rank near the bottom of the list in my humble opinion. The limited amount of voltage/amperage traversing the components while in that state should have no effect on the lifespan of your machine.
Most of the time motherboards are not high failure items, unless you get a bad batch and/or poor quality throughout production. In my experiences, plastic pieces are the first to go, lid latches, the lid itself from flexing on open, hinges, case bottom from heating and cooling, etc. With daily use and even the best care these pieces still break on a more regular basis than a motherboard that is always receiving power.
Also of note: A recent thread on the Linux Thinkpad Mailing list was discussing a development with Lenovo notebooks and the 65W Power Supply units. Main point was that the 65W adapter with the added power of the battery was not sufficient for high intensity loads and could easily damage the motherboard, hard drive(SSD), RAM. Suggestions were to not use a 65W brick at all(use the 90Ws) and to also leave the battery in, it was designed that way. :)
So, unless you are absolutely certain that your notebook will never use over the power stated on your brick, I would leave the battery in period. You may well end up doing more harm than good.
Thread is located here
In general, you should be fine running a laptop off of only AC power. The only issue with it would be when you're using "dirty" power, but that's not a problem for pretty much any industrialized country or region now-a-days.
Disconnecting a battery when it's fully charged can help extend its useful lifespan, as well as the single charge time. However all batteries degrade over time, and the extent to which disconnecting it will help is very dependant on the type of battery, amount of charge on it, and numerous other factors. Following the manufacturers recommendations is probably your best bet.
5A laptop without a battery is basically similar to running a desktop without an (online) UPS.
Basically, As you have noticed, there are a few "extra" circuits on a laptops motherboard which allow it to control a battery, however, you can always buy an extra battery and it would not really affect the laptop as a whole.
Also, some laptops which have smart/green/power saving specifications may be set in ways that automatically make them run slower when the battery is on and the mains are unplugged.
But, to sum up, you have nothing to worry about by using it with the battery unplugged... but there is nothing to gain either and personally, I would leave it in.
I would like to say, that if you only run the laptop without a battery, possibly consider selling it and getting a desktop - you could probably get something a lot more powerful for the same money!
I have not seen any laptop that drains a battery considerably when it is turned off - even ones that have wake on lan enabled.
Hope this helps!
1I know this is an old topic, but want to throw this information out to everyone...
The best reason to remove a battery from your laptop is, it could be damaged or just wore out. When a battery gets to the point where it has a larger load (resistance higher than normal), it can cause the charging system to overwork, and therefore heat up the laptop. This condition can cause the laptop to turn itself off, and therefore you will loose any unsaved work. In addition, by overheating, you are damaging multiple areas of the laptop, e.g. overheating IC chips, and other components.
Oh yea, don't forget that data can become corrupt during a shutdown phase, because the data might be in the middle of a write-to-hard-drive function. Read-from-hard-drive is not an issue, because it is not in the middle of creating bytes stored to your hard drive.
Bottom line, get a new battery or you could lose something...
It is safe; however if you will be not using your battery for a long time you should discharge it to about 60% for the longest shelf-life.
Also, some laptops do use the battery slightly when under large loads (my old Sony would actually discharge the battery even when I was plugged in if I played games with high settings)
I was once told by a Toshiba tech to remove the battery and just use the outlet.
Some details:
I have a notebook, that I had to replace the battery that came with it. It came with NO manual, you had to get it online. If you wanted a printed one, you had to print 68 pages, I didn't. So I didn't know that you have to use the battery until it's below 50% before you plug it in. Bought another battery, I did what I was told to do, use the battery until it was down to 50%. This battery died too. I talked to a Toshiba tech, and he told me to remove the battery and just use the outlet. So I used cardboard to fill in the area where the battery was and covered it all with clear tape. Works fine. He told me that it died because I was over charging the battery. Something I didn't know.
2It won't do any harm, but you will lose out on the built-in UPS that the battery serves as when the laptop is plugged into the mains.
You will not really gain much in the way of battery life either, as Lithium-Ion batteries degrade in time, whatever you do.
What effects them adversely is heat, so if you remove it, it is best to keep it in the refrigerator, in an airtight container. Do not store it fully charged or fully depleted. Around 60% is best I have read.
I would leave it on the laptop myself. If your laptop's power options has the ability, do not let the battery fully charge to 100% (I let it charge up to 90%) and never fully deplete it.
Most of this is what I have learnt from Battery University.
The life expectancy of your motherboard shouldn't be an issue unless its really cheap/defective. I have several old laptops that are still going 15 years later, and they have not been treated kindly. However, if you think you really need to disconnect the battery when not in use, and you're decent with tools, you may be able to install a small low-profile SPST switch somewhere on your laptop case to do this.
Just curious...does your laptop feel warm with the battery installed and not in use?
If running the lappy without battery and connected to the mains, also make sure "hybrid sleep" is enabled in Power Management. That would protect your data in the event of a power failure. (read up on "hybrid sleep" on google or other site.
Take out the battery when laptop isn't in use! Unknown to some, certain software installed on laptop, can turn Your laptop on—or should I say bring it out of standby, and that would not be good if You store it in a carrying case, because laptop could over heat, causing a fire, or burn up the motherboard! "Because Your laptop is always in standby never truly shutoff" Some may think I am crazy, but I have shutdown my laptop before, and when I went to use it, I opened the lid, and it was already started! They are made this way so, the manufacturer can turn it on anytime they want too, even though they say it is so you can start it faster! Bull, it takes maybe 30 seconds to 1 minute to bring up a laptop after real shutdown! I think everyone can spare that short of time for safety!
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