I just got me my first 21700s, i try to store my batteries at 80% and realized this would be 4000mAh which would be higher than any fully charged 18650 (they are 5000mAH batts).
Hence inspiring this thread.
Also does this differ for your batteries stored outside your lights?
The capacity and percentage of capacity is irrelevant for me because they vary from battery to battery. I just pay attention to voltage.
For cells that will be used again within a couple weeks, I charge them to 4.2V when they’re empty. They then stay with my flashlight stuff until I need to swap in a fresh cell.
For cells I don’t plan on using for more than a few weeks I (dis)charge them to 3.65V because I heard that’s best practice somewhere, lol.
New Li-ions usually arrive charged to 3.8v and need to go on the charger to 4.2v, unlike Lipo that are at full capacity from new. My guess from this is that’s ideal storage voltage as it seems the same across all the manufacturers.
I don’t have a storage voltage, but I don’t let them drop much under 3v and prefer to keep them topped to capacity. mAh is just the size of the can, like tactical_grizzly, I don’t go on that.
Usually I try to leave the cells somewhere between 3.5V and 3.9V, except the ones in lights I use daily. Those get charged to about 4.1V and discharged to about 3.3V, very approximately, but it tends to take at least a few weeks per cycle, and often more like a few months.
For infrequently-used lights, it usually takes years before I need to charge it… even if I keep the voltage within a fairly narrow 3.5-to-3.9V range. Since I usually only want 5 or 10 lumens, batteries last a very long time per charge.
Basically the only time I ever fully charge or fully discharge a cell is when I’m running tests.
For deep storage, I usually do it at 3.4-3.5V.
For normal storage, 3.9V.
If I expect to use it, 100% charge until I get/make a charger that can set different SOC levels.
I fully charge my batteries and keep them in my flashlights. I don’t have any spares.
After when I use a flashlight for awhile, I top off the battery, and then start using my next favorite flashlight.
I’m not concerned about longevity of them. I have some Li-ion batteries that are 8+ years old and haven’t noticed any issues with them yet.
Compared to the NiCads of the past, these Li-ion batteries are a dream!
Most of them are kept at about 4.0v. Frequently used batteries sometimes are pushed up to 4.1 and then recharged when I know or suspect they are below 3.8v at the end of the day or use. Although people may be used to seeing a percentage on their phone, they really should be using a voltmeter. I think these poll questions as worded are doing a disservice.
Are there any chargers that can charge/discharge to a specified voltage?
Keep my emergency lanterns fully charged. Doesn’t do much good to have discharged batteries during a power outage.
Anything I’ll not be using for 3+ months gets discharged down to 3.6v-3.7v and into the fridge they go.
Chris
Hobby chargers like the good ol’ IMAX B6 have a menu setting to charge for storage. It won’t discharge the battery on my device though, only stop at 3.7V
The Opus 3100 V2.2 has a hidden slide switch under the bottom cover that limits charge voltage. It's set to 4.2v from the factory. The other settings are 3.7v and 4.35v. I cut a small hole in the bottom cover so I could easily adjust it to 3.7v for cell storage. The switch is undocumented in the owners manual. I learned about it here in a 3100 thread.
slmjim
Fully charged; topped off monthly. (usually)
I have some computer battery pulls that are over 10 years old and still work fine.
now someone chart how much you can save {money}
vs. amount of time and brain energy expended doing so
I keep my edc light pretty well topped off. Other lights that get less frequent use I prefer to keep in the mid 3V range, but I don’t go out of my way to charge or discharge to that level. If I notice they’re getting down below the mid 3 range I’ll toss them on the charger for a little while but I may or may not pull them before they get completely topped off.
This is pretty much what I do too.
For storage, I am only concern by voltage and don’t care about capacity and % of capacity.
This is a good question, as I know I’m pretty bad about this.
I tend to keep a bunch my lights fully gassed up and ready go, north of 4 v. Darkness might strike at any moment. This means the batteries in lights I use frequently get topped off a lot. I know this is a bad habit, as this is more than twenty lights and some don’t get turned on for weeks, but this is not always about being rational.
I keep a just couple of batteries fully charged outside of lights, just if I need to take a spare 16340 or 18650 with me somewhere. Batteries that I’m storing are south of 3.8 volts.
Storing all spares in the fridge is something I should probably think about. Good idea!
Whenever I get any new cells (discrete or included with lights) I always cap-test them, so they typically go back up to 4.2V, as I don’t stay up all night babysitting them.
I might give ’em a blast on turbo to burn off a fractional-volt or so, but that’s it.