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Battery Basics, Part 2 of 2

Last month, we examined the issue of depleting a battery beyond its nominal discharge voltage. Today we'll explore how to maximize the run-time of any rechargeable battery.

While it contradicts much of what many of us were taught in the early days, the most important thing you can do to ensure a dependable duty cycle is to charge early and often.

This will not harm the batteries. Modern chargers and batteries—NiCads, NiMH and Lithium—have sophisticated circuits that communicate data, which allows the charging cycle to be tailored to a specific battery's needs. Topping off a battery's charge, after even a few minutes of use or a couple of days off, keeps the pack fresh and ready to go.

Care and handling of batteries play a big role in keeping them from failing prematurely. Allowing batteries to cook in the sun until they become too hot to handle will eventually lead to failure of the thin separator film that keeps a cell's internal metal surfaces from touching.

This film can also be damaged by impact. Dropping a battery pack onto a hard surface not only leaves scars on the case; the shock from a fall of even a few feet can give the cells a concussion. In either case, a hole in the separator can allow the cell to short out. And a shorted cell not only fails to provide its share of the power your camera needs, it also draws power from the other cells in the pack. A battery with a shorted cell can self-discharge and be completely depleted only hours after being removed from the charger.

While exposing batteries to extreme heat leads to long-term problems, the effects of extreme cold are more immediately apparent. Serious cold—in the vicinity of 10 degrees Fahrenheit and below—significantly inhibits the chemical process that creates electricity. Batteries run out of juice much faster when they're cold. Fortunately this problem is reversible; warm the battery and longer run times will return. And since the loss of power from cold batteries is predictable, it's wise to take a few simple precautions to prevent your battery power from pooping out.

Keep spare batteries warm by leaving them in a heated place until they are needed. An insulated cooler will keep batteries from cooling off in arctic conditions just as effectively as it keeps drinks cold on a summer's day. Instead of adding ice, toss in a couple of chemical warmers to keep them warm. If you're on the go, carry spare batteries in your pockets, under your outer coat, instead of in your backpack. Swap batteries during the shoot, before they get too cold so they can warm up in your pocket before being put back on the camera.