When SSD drives were first introduced, they promised three advantages over conventional hard drives: higher performance, better stability due to the lack of moving parts and, lower power consumption leading to better battery life.
Whilst it's hard to argue with the first two points, I've often been asked whether SSD really improves battery life in a laptop/netbook. To find out the answer, I dug a little deeper into the numbers. Now, it's worth noting that there are many different types of SSD drives, and the technology is bound to improve over time. At the time of writing I can only go by the current crop. Please only use this article as a general guide.

I compared the manufacturer's specifications of three drives, all from Western Digital. The first drive is a standard 2.5" 5400rpm SATA hard drive, found in most laptops you can purchase on the high street. The second being a high performance 7200RPM hard drive - one which I use myself. Lastly we have the top end, expensive SiliconDrive III SSD.

CONCLUSION

A few things came to light with these figures:

• While there is disk activity, SSD drives do use marginally less power than conventional hard drives.
• While in standby/sleep mode, SSD drives consume MORE power than conventional hard drives. This is the sort of thing I have heard being reported by users of Crucial's 2.5" SATA SSD's. If you set the hard drive to idle after a short period (anything from 1 min to 5 min) in your laptop's power management then you will maximise this advantage.
• It's important to realise that even 2.5W is not going to affect your laptop's battery life substantially. While idling, my laptop (Dell Precision M4400 with Intel Core 2 Duo P9600 CPU) battery discharges at anything between 17WH to 25WH. A common CPU like the Intel Pentium Dual Core T4200 has a power rating of up to 15W/35W depending on CPU throttling. Amongst all the other components inside your laptop, the hard drive/SSD consumes next to nothing.

For those who can do without the other benefits of the SSD, such as less heat/noise, I am recommending that you stick with the hard drive, at least for a while yet. I was pleasantly surprised by the efficiency of the 7200RPM hard drives, having previously thought that it would be a lot more power hungry compared to 5400RPM drives. Hard drive technology has been around for a while, and it's no surprise to see that every effort has been made to make them as fast, big and efficient as they are today.

Author: Tom Lei.