How Often Do U Charge 18650 in Your Single Cell EDC light?

So my Fenix PD32 is with me some days and all evenings...gets use out to the mailbox, in parking lots, train station, walking dogs- occasionally strobe mode crossing street to a restaurant etc....I charge it once in a while and rotate spare UltraFire 18650s through it or sometimes pairs of RCR123A Tenergy cells. I use a Nitecore i2 charger usually...

My question is how often, with light usage like this, do you charge your EDC light? I don't want to wait too long and have it go out when I need it badly, but I don't want to unnecessarily shorten the battery life too much either.

buy 1 more 18650 battery? so that u can have 1 more back up

Get a volt meter. You should charge before the protection circuit cuts off power.

Li-ions: be informed, be aware and enjoy. Lots of important information on this forum and Battery University. Get a volt meter so you know when to charge and the voltage after you charge.

"An educated consumer is our best customer." Sy Sims

yoyoman said:

Get a volt meter. You should charge before the protection circuit cuts off power.

Li-ions: be informed, be aware and enjoy. Lots of important information on this forum and Battery University. Get a volt meter so you know when to charge and the voltage after you charge.

"An educated consumer is our best customer." Sy Sims

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I charge anytime I put any significant runtime on the light (ie more than a few mins at top brightness) or also once a week or so for a top off if unused.

Thanks @wiggle...that is the kind of empirical data I was looking for. I have had voltmeter and multimeters for more than 40 years and am familiar with various battery chemistries as a photographer, Amateur radio operator and RC fan..... I was asking what others do and you answered it. Other experience?

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Wiggle said:

I charge anytime I put any significant runtime on the light (ie more than a few mins at top brightness) or also once a week or so for a top off if unused.

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I do the same as Wiggle.

I always check the voltage before and after charging, so that I get a feel for how much battery capacity that my typical usage requires.
If I see my battery below 3.8v at any time, I recharge it.

For resting the battery for storage, I charge it to 3.75v and keep it in a cool place to sleep.
They do have a shelf life, so they won't last forever anyway. But heat and high(or very low) charge states are bad for storage.

Frequent charging is not harmful(as long as it isn't overcharged), and in fact it can extend the cycle life of the battery. So deep discharging is not optimal.

With my PD32 I use it almost exclusively on medium (70 lumens) and it's 2-3 weeks between charges unless I have a heavy usage day.

BTW: I use Redilast 2900's



@ twl, Love the sig line, best movie EVER!

I run a m61w on a single 18650. I use it for work and brought two batteries to rotate as needed. I wait for the battery to run down below 3.4 which is the lower range of the voltage required for regulated run. I thought I'd be swapping and charging more frequently then I am but with the amount of use I put on the light I'm charging up the battery every three weeks.

Once I get any of my 18650's to 3.7-3.8v I charge them up. I only have a handful of lights that accept 18650's and I use them often enough that each cell gets charged at least once a month. So none of them are in 'storage' as they get electrons moving through them on a regular basis.