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Best Storage For Notebook Battery Life

SATA SSD Results

We start our testing with the most popular category for notebook users, SATA SSDs. These products give you the best balance of compatibility, performance, and pricing as long as your notebook still supports the interface. Newer, thin-and-light Ultrabooks, like Lenovo's Carbon X1, don't always support SATA. It's so thin that Lenovo couldn't fit a 2.5" drive in the chassis.

Notebook Battery Life

We really have to consider SATA flash-based storage as the baseline. If you can afford it, flash is where it's at. Current pricing is where it was two years ago, but that will soon change—for the better—with new 3D-NAND technologies.

Five years ago, a 512GB SSD sold for $800-1000 (Samsung 830 and Intel 520 Series). The Samsung 850 EVO 500GB sells for about $180 today, and the Mushkin Reactor 500GB goes for as little as $139.99. Getting longer battery life isn't as expensive as you might imagine. Our best result in the SATA category comes from the SanDisk Z410 480GB SSD, and it sells for as low at $163.

The difference between the best and worst battery life results was 161 minutes in our Lenovo Y700-17 gaming notebook. As we mentioned, this isn't a system designed for long battery life.

There are a few points to consider here. The SanDisk Z410 480GB is a DRAMless model, but not all DRAMless SSDs deliver superior results. The recently reviewed HP S700 500GB—another DRAM-less SSD—achieved 299 minutes of battery life. That's less battery time than the Intel DC S3500 800GB enterprise SSD that eats power like a great white shark eats baby seals.

Power Restricted Performance

The MobileMark performance measurement tells us the user experience in a power restricted environment. Notebooks will automatically reduce the CPU clock speed, system bus speed, and memory frequency when running on battery power. You can change the default settings in the BIOS and make other corrections in Windows, but the battery will expire much faster without these power saving features enabled. (We leave them in the default state for our testing.)

SATA SSDs also have internal states that reduce power consumption. Drives with DEVSLP can drop down into the low milliwatts range. The deeper the power state, the longer it takes to wake the storage device. That adds latency, but not all devices need the same amount of time to recover from one of these many reduced states.

The wake time is usually determined by the controller or the firmware. Some controller makers develop the firmware in house, but some SSD manufacturers choose to build custom firmware. Developing firmware is complicated and expensive. Not every company has the resources to dedicate to corner-case work, like making efficient wake time.   

One solution is to omit some of the lower power states. The results show a number of drives that perform very well in a host system’s reduced power state but deliver poor battery life. There isn’t a single product we can point to as the clear leader. You will need to choose the category and make a selection based on your requirements.

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