Do rechargeable lithium-ion batteries lose charge in the cold?

[DirtNap]

Lithium tech is very robust and should have relatively low losses due to cold temps. Two bigger concerts are quiescent draw: all IC based lights have a draw when not in use. Unscrew the light slightly until you can’t turn it on and make it a habit. 2nd issue is cold weather CHARGING not discharging. If you need to charge cells when it’s below freezing, warm the cells up before charging to above freezing to avoid cell damage.

[Terran Terran]

[David D]

In my research of headlamps (I get obsessive and have ~70 pages of notes/reviews/test results), idle drain seems to have been reduced to inconsequential level in the most recent models.

For cold winter (-20C, not “California cold”), high run time is needed because it will be 50% of room-temp tested and maybe 25% of spec given marketing inflation.

Focusing on minimizing weight, these were most promising for winter use:

• For sustainability reasons (shoot me), I’m steering clear of built-in batteries which seem to offer ~ 25% extra run time for the same weight
• I’m aiming for test results of at least 100 lums @ 8 hrs room temp for 4hrs of -20C emergency hiking and more at 50lums if really banged up.  Safety first @ -20C
• The newly released Nitecore HA15UHE looks promising for winter @ 2.3oz if willing to trade off lumens and run time for an ounce (I’m guessing ~ 5 hours @ 90 lums @ room temp).  Looking forward to someone testing it.
• Most promising next up in weight (3.5oz) & run-time, Fenix HL32R-T but then have to accept no red mode and proprietary battery.  No independent tests but their marketing inflation is more reasonable than Nitecore’s so guessing at ~ 80 lums for 7 hours at room temp
• Most promising next step: Fenix HM62-T gives much better run times (11hrs @ 120lums @ room temp) if willing to eat 4.4oz.  But its magnesium body gives it the edge over 5.0-5.5 oz rivals in its performance.
• Going all in on run time, Nitecore HC60UHE (5oz, ouch, no tests yet but but doubt anything can touch it for run time at that weight (sorry Zebralink, you don’t charge) based on its 4000mAh battery and UHE LEDs)

Its a shame no one makes a decent 18350 powered model, that battery seems like a sweet spot for winter day hike use where emergency is a phone call away.  They’re either magnetic charging (Skilhunt, extra cord) or old school (Sofirn SP40A, no red light, micro usb = extra cord or adapter to lose, unregulated so doesn’t hold setting; HS40 or Wurkkos HD15R insane temp regulation) or junky (Wuben E7 reliability)

A quick comparison of Nitecore’s spec’ed run times vs tests for a a handful of promising models: spec run time is ~ accurate if accepting very quick ramp down in UL models or ramp down ~ 60 mins in for beefier models, to ~ 1/3 to 1/2 spec’ed lumens.

[DirtNap]

David D, I’ve been using the Wurkos HD15 as my go to for a few years. I have three of them in different colors and for the wife. Love the dual flood/spot light and the ability to swap for the shorter 18350 tube. In fact I use it with the short tube for everything short of four day excursions. Only thing I wish it had is fully customizable UI and smooth ramping. I haven’t noticed any heat issues or much noticeable PWM strobing. Love that it’s USB-C rechargeable and the handy power bank function, although you have to test if your phone will charge off of it (mine doesn’t). Can you elaborate on the heating issues?

[David D]

DirtNap, the Wurkos HD15 replaceable short tube is a nice feature, not many lights seem to have it.  How much does yours weight with the long tube and 18650 battery?  The Wurkos spec is too light (70g+battery) to include the headband, unless it’s a short tube number.

This independent test found that it has aggressive thermal regulation in turbo mode, causing the light to cycle up and down and noticeably flicker while its ramping:

Another reviewer found similar behaviour:

Because it’s an unregulated driver, the light level drops over time but this seems to help keep it cool so it doesn’t swing its light level all over until a couple hours in, shown in the red curve’s uncooled tests.  So in 3 season use, it may not be a problem.  But the 2 cooled other cooled curves (using a fan) are probably a better prediction of how it would behave in really cold temperatures, where I’d want to use it, and it starts hunting up and down as early as 5 minutes in.

Edit: some brands using an e-switch seem to still cause that parasitic battery drain you mentioned

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