Here's the short answer for both of you... if you use drop-in batteries that have to be charged outside the mod you need to have a way to have a multimeter and know how to use it. If you have the money for it get an auto ranging meter, then you only need to set it on resistance or voltage to get your info.
Yeah, the .5 is toast. I am disposing of that one. The other one seems to be fine. Holding a charge. Staying above 3 volts. The second one got just a little hot. The first one was the really bad one.
Good idea Tim. If you have a battery that gets hot like that you need to let it rest for an hour or so on something non flammable and give it time to cool down. Also, if your batteries stop charging fully (4.2v) you should check them and your charger (both can be tested with a multimeter).
Most batteries have an average lifespan of around 1,000 charges or so before the performance of them starts to drop off, and it mainly starts with the charge time dropping off and they will die off quicker. Some new chargers do multiple tests both before and during testing to help ensure battery life, charging and safety. Check out the Nitecore D2 and D4 for ideas.
Also, Baditude is hard to get in touch with, but check out his blog here on ECF as well as the flashlight modder and rc car modder blogs for more info on lipo cells. For now, here is a Google doc with some interesting info:
https://docs.google.com/spreadsheet...0dSc01mUkl6RXNnM2o2R1E&usp=docslist_api&pli=1
Also Tim, keep in mind that any time your entire positive pin is moving it can be damaging the insulator around the positive pin and that alone will do very bad things to your battery and other important things. Make sure that of you have to tighten that positive pin under the deck that you pull the pin and check the insulator. If your entire build spins when you tighten a screw you should check the positive pin/post that makes the 510 connection. It doesn't need to be crunched down super tight, just snugged up.
That goes for all tanks and rba's too. The screw-in coils for things like protank and hand made coils for the r91/Kayfun fans. If your connections are not snug and insulators, they will arc and short and bad things happen.
If I remember my battery safety reading correctly that first battery at .5v on the multimeter is toast. I do not think it can or should be recharged. I think I read that a battery that goes under 2.5v won't charge on the Nitecore chargers. But go look it up to make sure. I do not know enough to advise on 2nd battery. I am a chicken and would toss it but that is me.
Shari, good memory on the 2.5v thing, I have pulled them back from as low as 2.3v but that battery is no longer used in high power applications.
Here's the deal, the difference between the batteries used for sub-ohm vaping and "normal" vaping (like the Provari) are minor, but the basics are that the sub-ohm batteries are "high drain" which more or less means that they can dump a huge amount of current (as amperage) through the circuit (your atty and coil build or heads) versus the much lower amount of current pulled at one-time-per-fire of a 10 amp battery (or similar).
The lower amperage rating means that the battery is designed to be stable at that amperage draw continuously (not forever, but think 10 seconds roughly) without having a critical failure. The higher amperage rating means basically the same thing but not quite; the energy transfer becomes higher and that means that more heat is created as that happens (also the reason the "cold cranking" amps are higher on car batteries, they function more efficient when not heated above a certain range).
The so-called "protected" batteries have different styles of protection in them to try and make them more safe for the average consumer, but they should never be interpreted as fail-proof even if they are in a regulated mod... my SVD had a battery short due to a bad insulator and it almost cost me a battery and a mod.
Remember, these batteries are not designed for what we use them for and they are the equivalent of the lighters we all used to pack multiples of when we smoked. Use some caution and you will be fine, forget to be careful and it can go very bad, very fast.