While most wireless deployment discussions center around security issues and of course ROI, a key hidden issue for most enterprises is the short battery life for the client devices. Because wirelessly connected devices are typically mobile, they rely on batteries, and batteries have not advanced significantly in years in terms of power capacity. And it's pretty much a given that you can reduce a vendor's battery-life claims by at least half. And this issue compounded by the fact that "802.11 is very inefficient in how it manages power," says Ovum analyst Richard Dinen.

In IT Wireless interviews with various enterprises deploying wireless, the issue of battery life was particularly acute for those whose workers are highly mobile. And of those mobile industries, health-care IT managers raised the issue most strongly:

• "It's hard to replace batteries a lot — charge, drain, recharge," notes Andrew Thomas, M.D., the assistant medical director at the Ohio State University (OSU) Medical Center in Columbus, Ohio. Worse, staff members tend not to notify IT if a laptop battery is drained or if the laptop is not working, since the laptops are shared with 40 other users and thus no one's direct responsibility. To encourage staff members to plug notebooks into outlets to be recharged, OSU is raising the power outlets' height as it remodels units, he says.
• Battery life is also an issue for PDA use, especially since PDAs can't be plugged into to recharge. Still, some physicians take them and live with the four-hour battery times, notes Tim Stettheimer, CIO of St. Vincent's Hospital in Birmingham, Ala. "They don't mind carrying around a couple batteries."
• For OSU's Thomas, poor battery life led to the failure of its experiment with thin-client tablet PCs. "We looked at Fujitsu and ViewSonic slates but the battery is gone in two hours. When the battery died, you had to reload the drivers for the device because everything is in memory," recalls OSU's Thomas. For vendors, the simple fix is to include persistent memory storage to retain data between battery swaps, but OSU's experience shows exactly how little the industry has thought about the issues of battery life in a mobile environment.

Generally speaking, there are two ways for enterprises to deal with battery-life issues. One is to have recharger units available in convenient locations for self-service recharge. These recharge racks typically are assembled by the IT department itself, since there seem to be no commercial products to charge multiple batteries simultaneously. The other way is to keep spare batteries available, with employees dropping off used ones for someone else to recharge.

UPS, for example, has set up battery racks in its package sorting facilities so workers can swamp out a dying battery for a freshly charged one (the old battery gets placed in a charger). These racks support dozens and sometimes hundreds of batteries. (Ovum analyst Dinen notes that some London subway stations now have such charger racks for cell-phone users.)

Because sorting staff at UPS tend to work five-hour shifts, they often can get through a shift with just one battery charge for the handheld scanners that the sorters carry. If not, sorters typically get a new battery in the few minutes time they have as they move from one truck or palette to another. FedEx's two– and three-hour sort shifts also fit within battery lifetimes. Still, warehouse-type operations such as FedEx and UPS must consider how to keep fresh batteries available for the various shifts, since workers usually share their handheld scanners, with each user logging in for his shift.

Deliverypeople can often circumvent the issue of battery life by having a recharger in their trucks or having a supply of batteries stored (such as for a PDA). And in more traditional white-collar environments, workers tend to dock their notebooks for part of the day, giving them a chance to recharge. In a worst case, an employee can plug in to a wall outlet.

Beyond the brute-force approaches of having charger stations and extra batteries, "there are some tweaks you can do [to the devices themselves]: Change the idle mode, for example, or use more efficient processors like the Intel Centrino," says Ovum analyst Dinen. But he notes that those are just incremental steps. Dinen hopes that a year-old initiative at the IEEE, the P165 working group, will help significantly extend laptop battery life, but such standards efforts take several years to accomplish their goals. In the meantime, mobile chargers and multi-unit charger stands may be the way to go.