I've been into flashlights for quite some time and own way more than I should. I'm about to move to rechargables; I've been 100% primary batteries. I think my first charger is going to be the XTAR VP4. I'll be using mostly 18650's which is where my questions relate. If a light can accept 18650's can you use batteries of any mAh? I'm assuming the higher number only adds to capacity/longevity? Also, if you fully charge a battery, what is the shelf life? At what stage in the battery's use should you charge; almost empty, empty. Is it ok to just top off frequently? I know that there are others that probably understand this chemistry better than I. Thanks.
Here is what I understand.
Topping off won't degrade the battery very much. I do it often.
Shelf life is good. Not sure of the exact time, but batteries that I've charged up months ago are still around 4.1x volts
These are not like the NiCD type of batteries that generate a memory affect.
They do lose capacity over time but its small and you should get lots of service before needing replacement
You can use 18650's of different capacities, but I'd recommend the 3100mAh or 3400mAh for longer run times.
You don't want to run a lithium ion below 2.50 volts as you will damage it. I usually recharge well before then.
A protected 18650 has a small circuit board that shuts of the power when it hits 2.50v. They are a little more expensive.
However its easy to recognize when the battery is below 3.0v because most lights won't function at the higher levels anymore.
Most of my 18650's are "unprotected" raw Panasonic cells with flat tops. I use them in the Fenix lights.
I have some protected ones for when I need button tops for Nitecores, EagleTacs, etc that require them.
If wanting to store a lithium ion for a long time, I find that they come shipped around 3.6 to 3.8v.
However most of mine I just keep topped off.
This is what I do. Others may have better suggestions. Since I have a voltmeter, lithium ion doesn't bother me as I regularly can know the charge (voltage) my batteries are at. If you don't have a voltmeter, then a charger with digital readout would be good. You can just pop the battery in to see what its voltage is.
