Do all flashlights slowly discharge when not in use?
I was thinking about buying a wurkkos fc11 as my first flashlight but it said they recommend untwisting it in a review to avoid making a connection so it doesn’t discharge while not in use. Do I need to worry about that with all flashlights? I was planning on keeping it in my backpack so I have it whenever.
Mechanical switch lights like the Convoy S2+ do not have any parasitic drain. But be aware that the batteries themselves have some self-discharge, Li-Ions are the worst at something like 5 percent in the first 24 hours and then loses 1–2 percent per month. Protected Li-Ions are even worse at 4-5% per month.
If you need to keep them stored for long periods, get an AA-compatible or dual-fuel flashlight and use Eneloop batteries for rechargeables, or Lithium primaries if you don't need/want to recharge.
To add to this, if you are going to store your Li-ion batteries for any period of time then you should charge them to 3.7v instead of a full charge. This will extend the life of the battery
Good tip, but the OP should be aware that when at 3.7V they have only ~50% charge in them, so remember to also pack a spare or two (at the same voltage) to have the same total runtime.
In general, recharging them before use is better - if you're preserving battery life as much as possible the ideal profile is to charge them to ~4.1V, use until ~3.5, then store at 3.6-3.7 until charged for next use, ideally minimising time sitting at full. Going below 3.4ish takes progressively more out of the battery life.