why is battery life different?

Simple question, but I don't think it has a simple answer.. let's say there are two laptops with identical configuration, why would one have better battery life over the other? I've read that it might have to do with firmware, but how can this make such a difference?

Each component has its power draws, and on a similar or identical configuration, with the same or similar battery, why are there such discrepancies? Initially, I thought about it similar to overclocking, each battery is slightly different, hence how long it lasts can vary. But then if this were the case, then laptops between manufacturers shouldn't differ that much since it's distributed randomly (ie. we know that Sony used to, or still makes, batteries for several well known companies such as Dell, etc.) Any thoughts??

 

well it might be one is on power saver and the other is on performance mode. also if the battery isnt EXACTLY the same, but similar, it will be different

 

You really don't get identical notebooks unless they are the exactly the same model or manufactured by the same ODM with exactly IDENTICAL specs.

For example even if notebooks have the same size screen they can vary quite a bit in power draw. The mainboard is likely to draw different power levels as well. GPU can be clocked differently and hence draw slightly different levels. The are also different thermal solutions inside the laptop (fan(s)). Battery capacity also can very quite a bit etc.

There is really too much variables. Only the CPU may consume the same power.

 

If everything were the same, then the battery life would be the same as well, for example, if you outfit an HP and Dell similarly, their batter lives are going to be in the same range as well.

Discrepancies occur because of different batteries that each company uses - even if they're manufactured by the same company, they're still different batteries. And the different screens and motherboards that companies use. However, overall, most computers with the same outfit have similar battery lives.

 

there is a misconception that computers are precision instruments like scalpels, but they are not.

there are so many factors that go into how long a battery will last that your question is almost unanswerable.

example, even if an identical computer is running even 1 degree hotter than another, that will affect battery life.

 

Ok maybe if I used two concrete examples that were tested, it would help me better:

Lenovo T61, 5.3lbs vs Dell Vostro 1400, 5.39lbs

T7500, X3100
14.1" WXGA+
2GB/667MHz
160GB/5400RPM
8X DL DVD Burner
Intel 4965AGN
Bluetooth
56WHr 6-Cell Lithium Ion Battery

Both have this configuration, same settings software-wise (torture test). What would make the battery life different by 20+ minute (for the Dell, 20 minutes out of about 150 minutes is pretty significant, approx 13%)?

How reliable can reviews really be if 1 degree difference affects battery life as drastically as you say?

 

please point out where i said that 1 degree change in temperature affects battery life drastically?

the POINT is that, using your example, if one notebook has better airflow or better engineered internal cooling, then it can affect overall times.

you are falling into the misconception that, as i said before, a computer is a precision instrument. it is not. similar spec'd computers can have different SuperPi results, etc. there are way too many variables within a computer (hardware, relationships between pieces of hardware, quality of materials used in parts even within identical parts/lines/models)

and guess what ? reviews for battery life are not that reliable, you're just making that assumption. want proof? go search the forums for any battery related post and see how many posters have disparate battery life times.

 

The assumption that they are the same is flawed from the get go and thus makes accurate comment hard. But that said, as has been stated, different cooling systems both in their capabilities and the thresholds the BIOS sets to trigger activity can matter. Other than CPU under heavy load the screen likely uses the next most power are they exactly the same? If they are not the exact same battery and interchangeable then there is at least part if not all of your answer.

 

As said above, battery life is not exactly a precise measurement. It depends on a lot of unknown or random factors.

But getting back to the original post, yes, firmware or software differences can make a difference too. What if one laptop has a bios that makes it run the fans more often at higher speeds? That takes more power.
What if the firmware for some piece of hardware prevents it from going into sleep mode as quickly as it should? It'll use more power then.

Battery life varies both with hardware, with physical layout of the system (airflow, for example), with the environment (temperature, possibly humidity too) and with software.

And even the battery itself isn't going to behave the same way two times in a row.

 

Some factors:

The voltage ranges encoded into different Intel CPUs with the same model number can be different.

Different hardware designs and BIOSes can have different levels of power saving through components turned off during battery operation.

Different displays can have different brightness levels and associated power consumption.

6 cell batteries come in a range of capacities.

Basic software configurations can have different numbers of background processes which affect the time the CPU can be an a low power state.

John