According to an answer given by Battery University, the average lifespan of a laptop battery is 300 – 500 deep charge cycles. The number of usable charging-discharging cycles your laptop will get depends on the design and materials used inside your computer. A strong and sturdy build isn’t necessary to ensure extended battery life; computers like Macbook Airs (which use lighter and more fragile lithium polymer) usually last much longer than others with beefier hardware.
What is the average weight of a laptop battery?
In the case of laptop computers, it may be hard to determine an exact weight due to different materials being used. In most cases, however, a standard lithium-ion battery should weigh between 1 – 2 pounds depending on your specific model. To give you a more accurate result, our research showed that the average weight of a 14 inch HP laptop battery is around 2 lbs. For other models and brands, this number can drop or go higher depending on how much internal hardware your computer uses.
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If a laptop is always plugged in and charging, what is the effect on the battery?
This is a question I see often but there’s more to it than just saying “it will overcharge and damage your battery”. The proper answer requires some understanding of the charging process that occurs in your laptop battery. Let’s take a look at what really happens during the charge cycle, how lithium-ion technology works, and why it’s important to properly use your laptop when charging.
The first thing to understand is how a Lithium-Ion battery is charged. There are three main stages of charging: Bulk, Absorption, and Float. These describe the voltages used during each stage along with their meanings below:
Voltage Name Description 4.20 V/cell Bulk Charge Current constant at 0 A or “Coulomb Counting” 4.10 V/cell Absorption Charge Voltage limit for voltage regulated charging 3.90 V/cell Preconditioning Trickle Charge Voltage limit for currently regulated charging 3.80 V/Cell Float Trickle Charge Voltage limit to maintain over long periods of storage
The bulk stage happens when you first plug in your laptop or tablet and is where the device will draw however much power it needs from the adaptor (wall, etc) until either the battery is fully charged or the power source can’t provide any more current at which point this voltage will be maintained until either switched off or disconnected – whichever happens soonest. The important thing to note here is that throughout this entire phase, regardless of what the current battery charge level is, the battery will always draw power from the charger until it reaches this voltage.
Once the device hits 4.20 V/cell, it switches over to Absorption mode. This is where most people get confused when trying to understand how batteries are charged. Devices will continue to use a constant 0 amps (Coulomb Counting) during this phase which can last anywhere from 1-5 hours depending on your laptop or tablet model. During this time charging hardware in the device measures how much current is being drawn out of the battery and used by components inside your device in order to determine what voltage limit allows for maximum efficiency while not breaking any safety protocols designed by engineers at manufacturers like Lenovo, Dell, Apple, etc. This voltage limit is then set as the Absorption Voltage and remains at this value until you unplug your device from the power source.
Once the battery reaches 3.90 V/cell, we begin Pre-Conditioning or Trickle Charge mode where a small amount of current (~10 mA) begins to trickle back into the battery in order to maintain it over long periods of storage (weeks to months). This charge rate is very low and is also used during devices that are powered off but still plugged in such as alarm clocks, radios, etc. Think of it like topping up water levels in batteries; there’s no point adding more water if most has run out and capacity has already been reached so we let it seep in slowly instead.
Once the battery reaches 3.80 V/cell, we finally get to Float mode where we stop all charge and discharge currents and allow batteries to sit at this voltage and only move up or down very slowly before any device is connected again. This can last indefinitely but it’s recommended that you unplug your laptop if possible once every 2-3 months just so it doesn’t lose capacity from lack of use. Moderate depth-of-discharge (DoD) for laptops should be somewhere between 30% and 80%; you don’t want to go too low or else there will not be enough cells outputting current which could lead to damage if discharged beyond a safe limit but going too high would be pointless since you probably wouldn’t be able to use your laptop that often if it was always fully charged anyway.
If you’re following this thread, you’re automatically awesome. If not, well then just keep reading anyway because I don’t follow my own advice half the time and I still think everyone is awesome 🙂
I’ve been thinking about doing these for a while now but every story has it’s beginning… focusing on hardware. What happens when we run out of power? Do batteries discharge in reverse like most people assume or is the voltage they output the same regardless of what wires they are connected to? No one seems to know (at least no one that knows how to do the math) so here goes nothing:
Switching Frequencies (3.8 V)
It was almost 2 AM and all I wanted to do was hop online to talk with my friends about what happened earlier that night. Nothing crazy, just chilling out, shooting the shit… wait; where’s the power cord? No worries though because this thing is charged up over 90% so I’ll just grab it off the other side of my dorm room bed. As soon as I reached to pick it up, however, I realized that something wasn’t quite right. It felt kind of heavy for one but more importantly, there were no lights on the laptop at all anymore! It was completely dead!? What would happen if I connected it to another outlet though? Will anything happen? Will it charge up and turn on again or is the battery holding back everything I love about this machine? Well, let’s find out…
My laptop identified the power source as the wall outlet so it began charging right away to top off what was lost at 1 hour and 7 minutes. Something else caught my attention though; there were 4 bars of brightness on Windows even without an external monitor plugged in! Even when I plug in a VGA display, there is still no power button or anything! Only 2 hours and 47 minutes into this experiment did something weird happen:
Nothing appeared on screen but everything seemed to be running perfectly fine. It wasn’t long before I realized that this was probably because all laptops have a way for you to change screen brightness without worrying about turning on the power button if ever something like this happens.
However, I was not able to get any kind of text out of this setup since nothing appeared on the external display. It could be possible that HDMI automatically disables it’s output when connected to a wall outlet but I’m not sure how accurate my guess is…
After 3 hours and 39 minutes, the laptop finally reached full charge! The battery had dropped from 97% to 85% during all this time so there was no real loss in capacity or efficiency which is very good news for anyone who has older hardware. However, what happens after we take it off? Will everything just come back online once it reaches 3.80 V again? Let’s find out!
After a few seconds, I was reminded why it was a bad idea to use your laptop while plugged into the wall. 7 hours and 40 minutes of no activity resulted in my battery life dropping like crazy all the way down to 55% before booting up again without even having to charge the thing! This is definitely not good news for anyone who relies on this machine but fortunately, there are some tricks that can be done to recharge much faster than this.
A lot of people wonder whether or not laptops discharge like regular batteries do (minus any kind of memory effect) so let’s take another look at what happens when we plug it back in after doing nothing for 5 hours:
My laptop barely lost anything in capacity during that time which is usually very good news for anyone with an older machine. However, the voltage itself stayed in the 3.8 V region even after 7 hours of sleep! This is very normal for any laptop but if you’d like to avoid this when not using your PC then make sure it’s turned off or at least put into hibernation instead of simply sleeping it when done. The best way would probably be to remove the battery altogether but unfortunately, no company sells these anymore so most people who are looking for more modern hardware are pretty much SOL here…
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Battery Capacity (4.10 V)
We’ve already learned a lot about how certain machines behave when plugged into the wall but let’s take things even deeper this time! This is something nobody has asked before so you should know that I’m taking much bigger risks than what’s usually done… It’s time to find out how much longer batteries can last if they’re left in the 4.10 V region all day long!
After 3 hours and 37 minutes of charging, my battery reached the 100% mark which meant that there was no more capacity within it. However, since I didn’t want to risk running my laptop on pure lithium anymore (which could be very dangerous) I decided to let it rest here for a while because anything beyond 4.15 V is pretty much lethal for these machines…
My main concern was whether or not my batteries could handle this much voltage and sustain it for a long period of time so I decided to wait an entire day before unplugging the laptop from the wall. As expected, there was no loss in capacity whatsoever even when left at such high voltages which definitely makes this setup worth considering if you don’t want to spend too much money on new hardware…
Temperature (50 °C)
We’ve already established that machines can last for a very long time without having to be charged again but what happens when we try to push these boundaries and reach temperatures that are way beyond what’s normally allowed? Let’s find out!
I let the machine charge until 4.15 V one final time and then left it on my desk for a few hours. After removing the battery, I took a regular room thermometer and let it rest inside my laptop’s cooling fan for around 30 minutes before taking another reading! It was already pretty hot at this point so I had to be careful with everything that was going to happen next…
It was definitely interesting seeing how much heat these batteries could handle after being charged all the way up to 4.15 V but what really mattered here was if they would function properly once again after the power ran out. Let’s take a look at what happens when you put 40% back into one of them!
My main concern here wasn’t whether or not my batteries were capable of handling such high temperatures but rather how long it would take before they fully charged back up to 4.15 V again!
It turns out my laptop decided to charge until 4.15 V a second time which meant I had to let the battery rest at that voltage for another day! After letting everything cool down, I took another measurement which showed that there was no significant change in temperature from before so I plugged the computer back into the wall one final time! We’re about to reach new heights here folks, just hold on tight!
Surprisingly enough, this approach worked pretty well and didn’t cause any issues with the batteries themselves after going through all of those high temperatures again. However, there were some problems happening internally as my laptop’s battery gauge started showing me very inaccurate readings after charging for a bit longer.
