How to compare battery life of two laptops?

modeonoff

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Hi, I want to compare the battery life of two laptops to see which one could provide longer battery life while I am on the go. Obviously I cannot take both out and have them do the same things at the same time. Is there any test that I can do at home?
 

modeonoff

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Thanks but obviously I cannot have both machines doing the same tasks at the same time. How do those people test the battery life by making them playing videos continuously? Is this a good approximation on how the battery life of both machine are "relative to each other" in practice? I guess there are two things to test: 1. The battery life of two laptops with respect to each other. This allows me to determine which laptop to keep if the battery life is a key factor in selection. For example, if Laptop A lasts 5 hours and Laptop B lasts 6 hours, choose Laptop B. 2. How many hours can each last in a single charge. Ideally I want to know the results of both tests but right now, Test 1 is more important.
 

modeonoff

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What do you mean by "cue up" videos? If I have a list of videos from the computer not used and test the other, at least I need to search for the series of videos before playing them. So I have to be next to the tested computer all the time? There are also time lost during typing of each videos on the laptop.
 

USAFRet

Titan
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In my NAS box, I have about 4TB of movies. Mostly ISO files.
On the PC or laptop, VLC.

Put several hours of movies into a playlist, click the GO button. I think I put 8 movies in each.
Or you could put one movie on a repeating loop.
Play, and see when the battery runs out.
 

USAFRet

Titan
Moderator
An example intermediate test, after 2 hours (1430->1630)

2x Asus Transformers.
T100T on the left, T101HA on the right.

T100T, 2GB RAM, 32GB eMMC drive
Purchased August 2015


TT101HA, 4GB RAM, 64GB eMMC drive
Purchased March 2019


2 hours video playback, similar settings.
Retrieving the movies via WiFi, off the NAS box.



T100T @70%


T101HA @79%
 

USAFRet

Titan
Moderator
For testing battery life, you can have all the fancy apps you want, but there is no substitute for actual time.

Now 5 hours later of continuous movie playback, the two Transformers are at 31% and 49% battery life left.
Substitute your personal use case for "movie playback".
 

USAFRet

Titan
Moderator
Taking this 'test' to its inevitable conclusion...

Playing continuous movies:

The T100T shut itself down at 2120 - <5% battery at
6 hours, 50 minutes

The T101HA throttled down to minimal power at 4% battery remaining at 2305.
Test aborted with 3% battery remaining at 2312
8 hours, 42 minutes


So, "How to compare battery life of two laptops?"

Set them on identical tasks, and see when they run out.
Nothing magical.
 

modeonoff

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Jul 16, 2017
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I went to youtube and found a 4K video. Then, I used a website to save it.

https://y2mate.com/youtube/2jm4wAABrMk

The best resolution it could save was 1080p (.mp4) Full HD. Then, I played this 7-hour video on my Yoga 730 15" 4K (i7-8550u). Set max brightness of the 300nits screen to max and battery mode to "high performance". Went to Nvidia control panel to switch to iGPU rather than Nvidia GPU. It lost 26% battery life every hour. It took 3.5 hours to use up 90% of battery life. Is this bad? Have I done something wrong? It seems to lose battery life twice as fast as your worse one.
 
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USAFRet

Titan
Moderator
I went to youtube and found a 4K video. Then, I used a website to save it.

https://y2mate.com/youtube/2jm4wAABrMk

The best resolution it could save was 1080p (.mp4) Full HD. Then, I played this 7-hour video on my Yoga 730 15" 4K (i7-8550u). Set max brightness of the 300nits screen to max and battery mode to "high performance". Went to Nvidia control panel to switch to iGPU rather than Nvidia GPU. It lost 26% battery life every hour. It took 3.5 hours to use up 90% of battery life. Is this bad? Have I done something wrong? It seems to lose battery life twice as fast as your worse one.
Your laptop is different than mine. Your i7 sucks a lot more power than my Intel Atom.

The Asus Transformers are known for long battery life, because they are very low power systems.
Video playback isn't really task intensive, so these devices suffice.

These Transformers aren't for gaming, Photoshop/Lightroom, number crunching, CAD , etc, etc, etc.
Basic web browsing, email, movies and music. Little travel devices.
 

modeonoff

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Jul 16, 2017
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Your laptop is different than mine. Your i7 sucks a lot more power than my Intel Atom.

The Asus Transformers are known for long battery life, because they are very low power systems.
Video playback isn't really task intensive, so these devices suffice.

These Transformers aren't for gaming, Photoshop/Lightroom, number crunching, CAD , etc, etc, etc.
Basic web browsing, email, movies and music. Little travel devices.
Is my method correct? Is there any point to repeat the procedure with the Nvidia GPU turned on, with/without under volting?
 

USAFRet

Titan
Moderator
Is my method correct? Is there any point to repeat the procedure with the Nvidia GPU turned on, with/without under volting?
Your method is "correct", if that's what you're trying to measure.

Playing around with turning things on and off only matters if that is the way you're going to use the laptop.
Your specific use case matters far more than trying to get some max battery life number with contrived settings.
 

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