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Do all flashlights slowly discharge when not in use? (kbin.social)

submitted 2 years ago by [email protected] to c/flashlight

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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.

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[–] dmenezes 14 points 2 years ago (3 children)

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.

[–] unpunctual_bird 7 points 2 years ago (1 children)

Li-Ions are the worst at something like 5 percent in the first 24 hours and then loses 1–2 percent per month

I still remember dealing NiCad's 10-20% per month, li-ion was some space-aged future tech dream back then

[–] dmenezes 4 points 2 years ago

Oh man, don't even get me started on the NiCads. My beloved old Ti58C calculator used a pack of them and it was actually what killed her :-(

[–] Adair21 7 points 2 years ago (2 children)

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

[–] dmenezes 3 points 2 years ago (2 children)

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.

[–] [email protected] 3 points 2 years ago

Should be closer to 60% but still, it's not in a long term ready state. Long stored batteries should be recharged before use.

[–] [email protected] 3 points 2 years ago* (last edited 2 years ago)

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.

[–] [email protected] 2 points 2 years ago

Worth mentioning that some chargers offer a storage option, charging to exactly 3.7V.

On a charger that doesnt have this, it can be difficult to monitor it closely enough to get that exact voltage.

[–] jerv 1 points 2 years ago

Li-Ions are the worst at something like 5 percent in the first 24 hours and then loses 1–2 percent per month.

Non-LSD NiMHs are far worse at ~30%/month. Thirty. Three-zero.

Despite all the adulation that borders on fanaticism, the tests I've seen on Eneloops fall short of claims. Short enough that I am of the opinion that anyone who dislikes Li-ion for self-discharge should not even think of considering Eneloops unless they are willing to admit that it's not about self-discharge and they simply dislike Li-ion. Yeah, sure, it's about double, but if something is stored long enough for that to really be a big deal then lithium primary is the only viable option.