Q. Do you recommend using 9-volt lithium batteries to replace standard batteries in smoke detectors so that the replacement cycle can be extended?—William P. Bivins, Greenville, NC
A. Lithium 9Vs aren’t recommended for smoke detectors unless you follow a strict battery replacement schedule. Those batteries maintain a high voltage until the end of their usable life, so they provide a much shorter “low battery” warning to alert you that it’s time to swap in a fresh one. Alkaline batteries, by comparison, have a more gradual voltage drop-off, prolonging the “low battery” alert and greatly increasing the odds that you’ll be nearby to get the alert.
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