Firstly, I will not portend superior expertise with all battery chemistry, at all. But I have been studying quite a bit lately and will contribute these links from ones who do, truly, seem to actually know what they are talking about.(Because like I say, I, am still gathering knowledge, and am far from claiming such.) I will contribute the following:
First, here: (Candlepower Forums, by way of Google)
What exactly does "IMR" mean?
Yeah, it's a bit technical, but when the posting author states, in his summary,
" Not all IMR cells are created equal. One cannot and should not make generalized statements about their performance, reliability or safety characteristics.", that seems something worth considering.
I also want to share this from a site worth taking the time to look over, specifically the chart middle of the page.
Lithium-based Batteries Information
Probably worth reading, considering thermal runaway doesn't seem like much fun. Whether it blows up or melts down. And short of chucking it into a bucket of sand, there is not much more you can do.
If, you even get that chance. (Don't ever throw a cell into water, K?)
Oh, also good practice to
not just leave your batteries a' charging and go off and do something else. At least until you have determined that your battery is stable. Here is a formula from a post over at Candlepowerforums, which is helpful if you are really interested in safety;
1. measure cell voltage. if it's less than 2.5v, throw it away.
2. charge the cell. if it gets hot during charging, throw it away.
3. measure cell voltage off the charger. verify it's between 4.1 and 4.2v.
4. wait 30 minutes
5. measure cell voltage. if it's fallen less than 4v, throw it away. Otherwise record the voltage.
6. store cell for 3+ days in cool, dry place.
7. measure cell voltage. if cell voltage has fallen more than .1v from the recorded voltage, throw it away.
Any cell that hasn't been thrown away by the time I'm through with step 7, I keep and put into my regular cell rotation.
This was in the context of someone verifying the integrity of salvaged laptop batteries (Of which the intended use was for a
single cell flashlight, not an e-cig, obviously held ALOT farther away from ones face than a flashlight) but if you look at it you can get a feel of what's necessary to determine stability of a battery.
And, here, I want to contribute a caveat.
I think it might be worth staying away from batteries with a "fire" in their name. It's just wiser, if for nothing else, value for the dollar. I know, so many vaping vendors stock them, but do the research and you will probably see what I saw. Bad performance at the very least.
Plus, when buying batteries of this sort consider some factories overseas in certain unregulated areas have been (insinuated from elsewhere) inclined to dissemble laptop battery packs then shrinkwrap them as "BlanketyBlankFire" along with a supposed XXXX mAH rating.
(Many times this is incorrect and I have seen batteries, in fact at one overseas vendor that advertise a " SuchandsuchFire" battery with the stated "mAH" rating printed on the shrinkwrap of the battery, and then list the
actual mAh in the description for the benefit of us, the purchasers.
This in itself isn't an indictment of all batteries with a "fire", just something that has been stated in other forums. So take it or leave it, just consider it.
Yet I haven't seen any bad reviews of Panasonic, Sanyo or AW. Anywhere. Why not spend a couple of dollars more and worry less.
But, hey like I said, I am just getting my tootsies wet into battery chemistry, so do the research yourself.
I just figure if I have a potential grenade that I am puffing on, well, a bit of study seems prudent. So, study. Then study some more.
I don't believe in freaking out and just not messing with something because of a "potential" risk, but it would seem wise in the context of rebuildables to vape with a protection circuit of some sort. While you learn. Whether that protection circuit is built into the mod,
or the battery if you
must vape on a mechanical while you gather the knowledge that might save your face
And as to the original query topic of the OP?
I don't, knowingly go below 1.2Ω .
My internal safety "muse" says, at that point, "No No No, big guy. You have a lot of life to live still. Keep the Ohms above this and tweak the atty instead. Or just up the voltage. Or something."
That voice hasn't steered me wrong yet.
And, also; consider investing in a Vape2Safe magnetic fuse. I think I got mine quite a while back for under 10 bucks. And it's the reusable version. You just slap it on the bottom of your unprotected battery (in a mechanical mod) and it activates the protection if your Li-ion gets too close to the under-discharge range.
Then you can take the Vape2Safe off, let it reset and
safely charge your 18650.
This is important, as most of the problems occur when the voltage drops too low
and is then put on the charger. Once again a good reason to not leave your battery unattended whilst charging.
Also a good reason to consider a battery charging bag. Put it over your charger and it acts as insulation.
Plus, You need a multimeter. Seriously. Check for yourself the voltage of the battery, and when it gets close to too low, put it back on the charger.
Oh, and lastly. Invest in a decent charger. Nitecore or XTAR. The XTAR VP1 is a nifty device for about fifty bucks if you want to spend it,
and if you can find one not sold out. EmpireMods has/had 'em.
They have a nifty lil readout that shows your exact voltage in real time
