Microsoft slashes backup power costs with lithium-ion batteries

It designed a system that's five times cheaper than a traditional data center UPS

Microsoft has come up with a way to slash the cost of providing backup power in its data centers using standard lithium-ion batteries like those found in power tools and electric cars.

Microsoft said Tuesday it has submitted the specifications for its Local Energy Storage system to the Open Compute Project, meaning equipment vendors can pick up the design and manufacture it for customers.

The LES can replace traditional UPSes (Uninterruptible Power Supplies) for providing backup power to servers and other IT gear, Microsoft said. A UPS is designed to kick in fast if there's an interruption to the main power, keeping equipment running during the seconds it takes for a diesel generator to start up and take over.

Traditional UPSes use lead acid batteries, but they're bulky and require a lot of maintenance. Microsoft says its lithium-ion battery system is five times cheaper than traditional UPSes, factoring in the cost to purchase, install and maintain them over several years. They also take up 25 percent less floor space, because they're installed directly within the server racks.

Microsoft joined the Open Compute Project last year. It was set up by Facebook as a way for data center operators to collaborate on low-cost, no-frills infrastructure gear that they can source from multiple vendors. Its mantra is to do away with the "gratuitous differentiation" many vendors bring to their products.

Microsoft already submitted the design for a blade server system called the Open CloudServer, which it uses to power Azure and other services. The backup battery system is designed for use with version 2 of Open CloudServer, which was introduced in October.

Microsoft is already using the lithium-ion backup system for production workloads in "multi megawatt" deployments, said Shaun Harris, the Microsoft engineer who invented LES, and who is showing it this week at the Open Compute Project summit in San Jose, California.

The batteries are hot-swappable, meaning they can be replaced without shutting down servers, and LES is suitable for data centers of all sizes, Harris said, including a data center closet with only a few servers.

The way the OCP works, equipment makers can now pick up the specification and, if there's demand for it, produce it for other data centers.

Microsoft isn't the only company using lithium-ion batteries for backup power. Facebook submitted a somewhat similar design to the Open Compute Project last year and is using that in its own data centers.

"The inflection point has just happened in the industry where lithium-ion is cheaper to deploy than lead-acid for a data center UPS," Matt Corddry, Facebook's director of hardware engineering, said last year.

Microsoft is one of several companies submitting new hardware designs for OCP this week.

James Niccolai covers data centers and general technology news for IDG News Service. Follow James on Twitter at @jniccolai. James's e-mail address is

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