SSD hard drives tank laptop battery life | Hacker News Reader

SSD hard drives tank laptop battery life

hackaday.com

13 pointsdous14 comments

Here's the original article instead of the linked meta-babble.

http://www.tomshardware.com/reviews/ssd-hdd-battery,1955.htm...

EDIT: After trying to read and understand the article, I'm beyond confused. According to the chart on

http://www.tomshardware.com/reviews/ssd-hdd-battery,1955-14....

There are two SSDs that consume less power both idle and under load than the tested HDD. There's no summary data for actual battery life. I think they're trying to explain the disparity by saying the HDD spends more time idle. I really can't tell from all the verbose and confusing writing.

HDD peek at a higher power level but they can read and write data without reaching peak power levels when reading and writing sequential data such as large media files. I don't think this is a big deal as other components swamp the SSD's power levels and it's not that hard to significantly reduce the power used in SSD.

Part of the problem with the tomshardware review is that it has been pretty thoroughly debunked. The test just ran through loops repeatedly until the battery died; what the testers ignored was the fact that since the HDD systems were much slower than the SSD systems the CPU spent more time idled waiting for io, leading to more power spent on CPU cycles and CPU cooling in the SSD tests. The test results fail to note the fact that the SSD systems would run through far more loops than the HDD systems and since the testing methodology was flawed we can't know how much of the battery power went to the CPU/fans vs. the storage systems.

Agreed, the EEE (on which I write this) has surprisingly short battery life for such a limited device.

However, the SSD more than makes up for the battery consumption by being silent, blazingly fast and mad robust (this is my four year old son's computer and he can drop it on the floor while the disk is running without killing it).

I can't wait for SSDs to become standard.

We use Compact Flash as hdd's is small embedded systems. They are 10x more battery efficient than a standard laptop hdd and twice as efficient as a microdrive.

Of course, the largest CF we use is 8 GB and the typical size is 2-4 gb. (I did my consumption tests on 4GB Sandisks). The smallest used in the article was 32GB. Perhaps power consumption increases dramatically with size in SSD's?

Some of the SSDs in the article are using sophisticated controllers that consume more power.

I have an Asus EEE and the battery life is so-so, good enough for a decent train ride. When I installed software (lots of disk activity) while on battery, boy the battery went down quick.

The old 900:

2 hours battery life.

The new 901:

5 hours battery life.

With the same disk (SSD), battery and screen. The only significant component change is the processor. If the disk peaks at 2W/4W (SSD/SP) and is mostly idle then you would really expect it to be lost in the noise of the 20W+ for the rest of the system.

Argh. Do you have the new 901? That's a big big difference.

Not yet, I was going to buy a 900 until I found out about the difference in battery life.

The article seems to contradict itself.

Also, these are still pretty new, and their power efficiency (and prices, ahem) will no doubt improve over time.

Agreed. There's nothing inherently power-hungry about flash. It's read cycle looks a lot like DRAM's, but there is no refresh required and the quiescent power is zero (duh, I guess: that's what non-volatile means).

A flash drive running full tilt and hitting all the cells as fast as possible is probably going to have power consumption about the same as a DRAM array of the same size and cycle time, so somewhere in the low-integer watts. If existing drives are consuming more than that at "idle", then it's pretty clearly a hardware bug that should be fixed.

Surely SSDs would also turn off and enter a power saving mode when not in use?

TFA provides enlightenment:

In contrast, flash SSDs only seem to know two states: active or idle. We don’t have specific information on this, but we received confirmation from two vendors that many flash devices don’t feature power saving mechanisms yet.

Reply on news.ycombinator.com