Protected 18650

Hey there,

I am new to the forums, having enlisted specially just to ask a few questions regarding protected batteries.

Recently I bought a focusable 100mW laser, and it takes 18650 batteries. It comes with a cheap charger and a couple of batteries, but I thought I would buy some decent batteries separately as well, just to have a few spare. Reading around on the internet, I found out that some batteries can 'explode' if over discharged. Is it better to buy a couple of really decent protected batteries, or loads of cheap ones that won't break the bank? If the answer is to buy protected ones, do I have to worry about buying an equally expensive charger that has a cut off, or will the cheap one that comes with the laser charge them just as well without problem? Furthermore, if I decide to get cheap batteries, do I run the risk of breaking my laser?

Many thanks,

James

Get an AW protected 18650. No need for top-of-the-line 2900mAh capacity or anything like that, just get the ol' 2400 or 2600.

Some lights and lasers automatically cut out at the low voltage threshold of a Li-Ion cell, but you generally can't depend on this, so it is best to go ahead and get a quality protected cell. Later on, when you get more accustomed to using the Li-Ion chemistry and get used to checking on your cells fairly regularly, you can venture into the world of unprotected cells. You can find many good OEM cells that are technically unprotected, but often are many times less likely to catastrophically fail.

LarryDFW on the forums here sells unprotected Sanyo 18650 cells. I'm particularly partial to Sanyo, but these will not cut out at the low voltage threshold automatically, nor will they cut out if you accidentally short them or pull too much current. However, their datasheet says they can safely supply over 5A, and real-world testing seems to show that even one or two amps more than that will only result in a little bit of reduced capacity. Not that anybody draws that much current in this hobby anyways....

As for chargers, the best "set and forget it" is generally regarded as the Pila IBC.

Personally, I'd buy 2 good protected batteries and the pila. That is the safest bet for someone who can't be bothered to check their voltages regularly or don't have a multimeter.

Or, you can read up on Li-Ion cells and charging at Battery University and, if it seems like you'd be comfortable with that sort of thing, then you can go with unprotected cells. That way, you could just buy the charger, scavenge for used Li-Ion cells, and be able to identify whether they are usable, usable but close to end of life, or dead.