> Nickel metal rechargeables are a good AA/AAA substitute for devices designed to tolerate their lower voltage.

Any device that can't is arguably broken as designed. Much of the energy (the majority, in a higher current application) in an alkaline battery is found under 1.2V.

See discharge curves: https://lygte-info.dk/review/batteries2012/Duracell%20Ultra%...

NiMH actually stays above 1.2V longer for all but the lightest loads: https://lygte-info.dk/review/batteries2012/Eneloop%20AA%20BK...

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jamesgeck0 4 days ago | parent [-]

Unless the device was designed around the alkaline discharge curve! Smoke alarms rely on the lower voltage to give sufficient warning when the battery is low, and mine refuses to operate at all when powered by a rechargeable battery.

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imp0cat 3 days ago | parent [-]

Try lithium-based AA/AAA rechargeables. These worked wonders for my finicky Instax Camera which refuses to use regular NiMH AAs because their voltage is too low.

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baq 3 days ago | parent [-]

The issue with these is the low battery warning. Once the voltage starts dropping you don’t have much time to notice. Not a problem for active devices, but things like door sensors may give you just a few days between 80% and dead.

	▲	imp0cat a day ago \| parent [-]
		Absolutely. Different battery manufacturers use different discharge profiles, some gradually lower voltage in a few steps, others may just die with almost no warning, so it might take a few tries before you find a brand that works for your device.