how to know if the screen brightness is reduced on battery mode?

So Its easy to find out if there are light sensors i guess? Is there any other possible cause for reduced brightness in battery mode (besides OS and light sensors)?

 

There's nothing stopping a manufacturer coding into the BIOS a lower maximum backlight brightness (actually controlled by the voltage range) for battery operation. I have a recollection of a notebook where the backlight brightness changed after a BIOS update. Fixing a BIOS-based limit would require identifying and editing the relevant bytes.

My Dell E7450 has exactly the same brightness range on mains and battery.

John

 

So, no easy way to change it. Thanks.
anyone knows how notebookcheck.com conducts the brightness measurments of the display? It kinda seems that either way it's a gamble, without a proper review.

 

Ambient light sensors: mildly uncommon, can be disabled. BIOS setting: almost never, who in their right mind would do this.

 

One thought is to do that in order to increase the running time on battary?

Can you explain what did you mean earlier when you said that the brightness measurements aren't clear enough in notebookcheck?

 

It does boost battery life. But preventing user control on this is strange. If you're not on AC you're more likely to be under direct sunlight, right?

Brightness measurements in NBC isn't clean enough because they don't specify what OS settings are used for those measurements. An educated guess would be the default from Windows/MacOSX, but we're not sure. They may or may not be using something else and they're not telling us.

As John Ratsey said, it's technically possible for laptop manufacturers to enforce a lower brightness level on battery power. So there might be some laptops that do this. However even if it's the case it's a very rare phenomenon. If you're in the market for something new I don't think you should be worried. If you have access to some old hardware that does this, please give us more detail, especially screenshots of OS power settings. I've never seen anything like that. Looks like other people in this thread haven't neither.

 

This basically, they give max brightness data, but all other data in certain review doesn't mention the brightness setting. If they say they measured 239 cd/m^2 on battery, we know it wasn't at 100% brightness, but we don't know if it was at 50%, 20% or something else. It basically makes it impossible to know what the number actually means.

As Mr. Koala said, preventing user control of brightness on battery is an exception, not the norm.

 

Mr. koala, i guess it matters when the manufacturer publishes the battery run time.

tijo, are you talking on the other measurments of the display, besides brightness? i usually guess that the brightness mentioned in reviews is tested on 100%.

I’m just trying to get a hang of how to know if the screen is bright enough.
unfortunately I can only count on the data that is given in reviews. Usually I check notebookchecks reviews and it’s just not clear enough. For brightness I look on NITS and on the pictures they take.

But after reading a lot of NBC reviews, I learned that sometimes they do mention when it’s possible to control the limited brightness and sometimes they don’t, so it’s difficult to assume that they are counting on the OS default when it comes to the screen brightness true potential.
As I said, the brightness in most of toshiba’s laptops in NBC reviews is disabled in battery mode (that is also mentioned on toshiba’s website).

 

Now that we have consensus that Dell offers the same brightness on mains or battery, going back to the original question in the first post, I note that the specs in the E5570 manual (pages 52-52) say 300 nit for the 1920 x 1080 panel and 200 nits for the 1366 x 768. The latter is a low brightness low viewing angle panel that is only fit for a skip but I guess it appeals to the bean counters who don't have to use the notebooks.

300 nits is more than enough indoors and is just about usuable outside in the shade. If you want to try reading the screen in the sunshine then 400 nits or more is desirable. Few manufacturers offer that level of brightness but, if you are in a part of the world where Samsung still sell notebooks (S Korea, China, Hong Kong and USA) then you might want to check their products.

John

 

Thanks guys, i really hope so because i'll probably buy the e5570. If all good i'll write a review in a few days.