LED flashlights can be extremely high-drain depending on the ratio of output to size, but "high-drain" with regard to battery performance may be lower than you

LED flashlights can be extremely high-drain depending on the ratio of output to size, but "high-drain" with regard to battery performance may be lower than you think. If 12 hours of constant operation will drain the batteries, low-self-discharge NiMH like white Eneloops or AmazonBasics will outlast any brand of alkaline. Higher self-discharge (loss of charge when not in use) offers more capacity, and only extremely low-drain devices will last marginally longer with alkaline. There are Li-ion button cells such as 2032, but their voltage range is higher than the disposables and their capacity is quite low. Their applications are fairly niche.