I am trying to decide whether to recharge my 18650’s right after use, or if I should wait until I anticipate using them again? I didn’t see any guidance on the flashlightwiki and no stickie here.
I use my various 18650 lights in 2 ways:
- One or two batteries get used heavily a couple times a month night hunting. Probably drained down to 25% capacity or less.
- I use same or other flashlights moderately a night or 2 a week to walk the dog or do something in the dark yard or garage
Wondering if I should charge after each use of more than X minutes… :8)
Li-ion don’t do well just sitting at full charge in heat. That causes them to degrade faster. Fully or close to fully discharged and sitting isn’t all that great either. They don’t have any issues with being topped up all the time though.
If you really want to maximize cell life:
Since your max usage is about 2 cells in a night hunting that’s something you can hopefully top up beforehand. I’d recharge those after that heavy night. Any other cells can be left just a little discharged away from sun/heat source (4.0-4.1V still gives you quite a bit of capacity stored but vastly slows degradation). Minutes is a hard one by itself but if you aren’t using a lot of energy in a given night you can probably go between hunting nights without too much trouble by swapping cells. If you use one quite a bit top it up fully or partially.
Simplest plan:
Keep 2 cells as heavy users since that’s about your max requirements in one night. Top them up frequently just don’t store in someplace above room temp. Don’t stress about getting a few more months or years out of the cells. If it was a good cell without a long time on the shelf before purchase you’ll still see a long life. You’re still way ahead in cost/runtime compared to primary cell lights.
When I got the Wolfeyes M90-13v back in 2006 (280+ lumens monster at the time), I bought several AW 18650 (2200 mAh) flat tops to feed it. I've used it ocassionally and always topped it off prior to setting them in the drawer. The most use was when I had to work night shift on a bridge and finally discharged down to cutoff voltage during one of the nights. At one time I had on long enough that the bulb deformed but no damage resulted. Light and battery still works fine to this day ableit with a slight aberation in the hotspot due to the bulb deformation (used for light ten minutes max since last year, usually a drawer queen with all the new cree led lights i've been collecting). Anyway, I recently got a Thrunite TN31 and borrowed these veteran AW 18650 to power it up. The TN31 lit up no problem. Used it 10 minutes on and off playing with the levels and seeing out far i can shoot the "bat" signal around the neighborhood and out @ my cousins ranch (the neighbors at the other end of the my block might think they are under helo watch). Batteries still was at 100% according to my ZTS battery tester.
Don't mean to drag this out longer than it should or sidetrack too much but I run AW 18500's (2 of them) in my Streamlight TL-3 (my work light) and recently killed one of the batteries because I ran the light until cutoff and carelessly forgot to recharge them until a week and a half later. When I did go recharge them only one would recharge. The "dead" one did not register in the charger and tested zero volts on the DMM, and did not register on the ZTS either. The good battery read 4.2 volts about a minute off the charger. I just want to emphasize that do not leave your discharged 18650s or other lions laying around too long after pulling them from use. I've tried the revival method found elsewhere on the this forum but no luck, the battery will not hold charge (it will read 4.2 volts off the charger but go dead within minutes). From my experience I had no issues with storing fully charged cells.