In most cases, today you’re better off using rechargeable batteries over disposable ones. They’re safe and reliable, they create less environmental waste, and as we explain in the Wirecutter guide to rechargeable batteries, they pay for themselves after about six recharges, even with the added cost of a wall charger (for which we also have a recommendation).

Going by a 2012 case study for the California Department of Resources Recycling and Recovery, we can estimate that about 4 billion disposable batteries are shipped to the US each year. That means the average US household burns through about 47 batteries per year. But you could buy just 12 rechargeable batteries every four years (the average life span of some popular rechargeable batteries) instead of the 188 disposables you would otherwise need. And you wouldn’t lose much performance: The best rechargeables can power your devices on a single charge for just as long as most high-quality single-use batteries can, but at a fraction of the cost over time.

However, single-use batteries are still the better option in a few instances:

Low-power devices

Electronics that constantly draw low amounts of power—such as some wall clocks, headlamps, or bike lights—work better with disposable alkaline batteries. Alkaline batteries start with a slightly higher voltage that in many conditions decreases faster than that of rechargeable batteries. Whereas an alkaline battery may drop from “powering” to “dead” pretty quickly, a rechargeable battery may hang on at a lower voltage for slightly longer, resulting in unexpected behavior such as dimming lights or a clock that can’t keep time.

Smoke alarms

Most alarm manufacturers recommend against using rechargeable batteries to power a smoke alarm. Smoke alarms that are not hard-wired into your home’s electrical system get power in one of two ways: a built-in battery designed to last up to 10 years, or a disposable 9-volt battery that you should replace once a year. No matter what kind of smoke alarms you have, according to the US Fire Administration, you should test the battery monthly and replace the entire device every 10 years.