Is Laptop Advertised Battery Life a Lie?

I have had many laptops throughout the years. I had a Dell Inspiron 6000 from way back in the day. Then an Asus and a few ones in between. I had a Dell XPS 15 9550 and now use a Dell XPS 15 9520. I had 2 Chromebooks as well. Both are Acer I believe.


If you have a smaller battery, they say battery life is about 5 hours or more. If you have a bigger battery, they say battery life is about 8 hours or more


Where in the world do they come up with these numbers? None of my XPS laptops came anywhere close to these numbers. If I'm using my laptop say 3 straight hours almost nonstop, my battery is going to go to zero soon. I don't think it's even possible for an XPS 15 laptop to go 5 hours straight before you need to charge it? By 5 hours, I mean if you are visiting websites or say playing youtube nonstop. I don't mean like you are casually web browsing every few minutes and then your laptop screen dims. If you are talking that, of course your battery would last you at least 5 hours. The thing is my screen brightness is at least 50% at the minimum. It's probably 60% and higher and even 80%. So that is why? However, what person is making their screen like 20%? That would be way too dim to do much and can't be comfortable if you using it for hours.


The thing is they advertise like 12 hours or more on a Chromebook. The last Chromebook I got, if I use it nonstop, I think it last at the absolute most 3.5 hours total before you need to charge it. This is when the Chromebook was new. However, I believe the screen brightness I use is always 80% to 100%. So that is why right? But say 50% screen brightness and say I go on YouTube and play a song on repeat... imagine a YouTube video where it plays a song repeated nonstop for 24 hours. That wouldn't be a real world test right?


Now if I use this Chromebook to do something for 10 minutes and then take a break every 10 minutes and repeat this nonstop with the screen dimming or screen turning off until I go back to what I'm doing, I could imagine the Chromebook battery lasting 8 hours at the minimum. Or like imagine using it nonstop for 2 hours and then not doing anything and then the screen dims and turns off. Then 8 hours later you go back to your laptop... well obviously not much battery is wasted so you still have a good amount of hours left right? The interesting thing about this is with the XPS laptop... that doesn't seem to be the case compared to Chromebooks. Anyone know why? If you connect external monitors to it while the screen dims and turns off... the laptop screen and the external monitors... then it isn't the case?


I use my XPS 15 9520 with my 32' 4k external monitor and 24' 1920x1200 almost always and plugged in. You should always have it plugged in correct especially if using external monitors? I recall unplugging it, battery drains much faster than compared to using the laptop by itself without monitors?


With Chromebook, I just use it as is without connecting to external monitors. However, it doesn't last longer than 3.5 hours if using nonstop. That is normal right? The other thing that frustrates me is a powerbank doesn't get more than 1 hour with my XPS 15 9520. If I use a Dell 18000 mah usb-c powerbank with it, it gets 55 minutes before it goes to zero. This is with my XPS 15 9520 laptop battery at 100% and the powerbank at 100%. If I use my Anker 737 powerbank with the XPS 15 9520 laptop in same conditions, I believe 1 hour 5 minutes. Is there a reason why laptops have such poor battery even with a powerbank? The Anker 737 powerbank probably lasts a lot longer with my Acer Chromebook right since the processor doens't use that much power? It is Ryzen 3 I believe. My XPS 15 9550 has i5-6300hq and the XPS 15 9520 that I use now has i7-12700h.



Why don't the manufacturers advertise real world battery life hours? I got to assume people who use MacBooks probably get at the most 5 hours on it if you are using it nonstop for 5 hours?

I'm sure the manufactures test battery lifetime while laptop, not in any use, they just charge it and see how long battery last.

There are dozens of variables.

"what person is making their screen like 20%?"
Mine is around that though that is because of a max brightness of 450 nits. The % scale is non-linear.
Laptops are fitted with various display panels some of which maybe down to 200 nits.
Also having the screen at 165 Hz rather than 60 Hz increases power consumption.
If there is video showing rather than a static website page that will increase power consumption.

Well that is 4 variables just for the screen.

Using the Wireless Card uses more power than Ethernet.

Powerbanks are just another battery with whatever capacity is printed on, no different from an internal Laptop battery.

"XPS 15 9520 that I use now has i7-12700h."
Same CPU as mine. It is for performance not low power consumption, you should get a Laptop made for lower power consumption, those CPUs used to have U as a last letter.

Laptop manufacturers always provide various Power Plans, one of which will be for lowest power.

If you want low power consumption you need to carefully choose a Laptop with that in mind before purchase. Your choice was more for a Laptop to replace a desktop.

Manufacturers will choose a configuration for their spec sheet, that may well be far from realistic usage scenario.

Battery life is a sore potion with me, now that laptops don't have removable batteries, so that I can carry a spare.

My experience using a laptop while on a plane trip is that the battery can run down very fast, unless I turn down brightness and turn off WiFI. Airplane WiFi, at least on American Airlines, is too expensive for anyone not on an expense account.

Also, I always look around for the AC plug, in case I need to haul out my AC charger. It's really frustrating when I get a seat without AC (despite looking at SeatGuru), or an AC plug that doesn't work. Flight attendants don't seem to care.