The settings of the headtorch will affect the actual battery life, but the consideration should be how long the battery will last at the maximum number of lumens. Bear in mind that a shorter battery life will mean you need to carry spare batteries or a solar panel to recharge, so if you’re trying to pack light for your adventure, a longer battery life will be key. As a rule, the brighter the head torch, the more power is required to keep it going, but if your torch has various dimming and strobing settings this will help preserve battery life when maximum brightness isn’t required. It’s worth considering also whether the output of a head torch is important for the activities you are using it for. Regulated torches run at the same lumen intensity until the battery is nearly dead, then enter a short low-power backup mode until it’s out of charge. Unregulated torches offer full brightness only when the batteries are new, but then continuously dims at a slow pace until the battery dies.