Eh, I dunno. I have very little knowledge in this matter, so here are a pile of assumptions and related stuff: I’m assuming that RMM is presenting this cell as a value proposition, eg “the best of the rest.” We don’t know who manufacturered it, and cell wrappers often do not tell the truth. Unless RMM says different, it seems that he was not confident enough in the “IMR” label to write it up in his own description. I’d say that this cell is in the class of batteries sold by Supfire, Solarforce, and other manufacturers in that class. EG one or more notches below what’s sold by Olight, Nitecore, Fenix etc. Frankly I have very little knowledge of cells which are not identified by manufacturer (Sony/Samsung/Sanyo/Panasonic/LG/etc).
I don’t trust unknown cells myself. If I haven’t been told what’s under the wrapper and seen something to back it up (distinct physical characteristics or matching discharge curve shapes) I seldom want to make a purchase. The main thing is that the price of the “good” cells is really, really close to the price of the other cells. I figure that I can leave the fries out of my next happy meal to finance the good stuff…
I had read that previously, and it was helpful, but I’ve seen so many differing opinions I don’t know what to trust anymore. He also doesn’t address the INR cells directly. So i guess my real question is, are the Samsung INR cells considered “safer” than a regular sanyo or panasonic?
My opinion is simple. I do not consider any Lithium chemistry “safe”. What are your qualifications for “safe” or “safer”? What specific event / problem / scenario are you trying to prevent?
99% of my knowledge on the subject comes from reading here and cpf and a few vaping forums. from what I can gather, Lifepo4 is condered “safest” because it can’t be overcharged and has lower energy density, and “IMR” is considered safer than LiCo because it has similar resistance to overcharging, doesn’t go thermally ballistic for no reason, and does better when used in a 2S configuration.
Safe is relative. The quality cells aren't going to spontaneously combust or explode during normal usage, but any device that can dump 100-200 watts short circuited is potentially very dangerous. I have done enough "accidental" testing with these things to feel confident that they aren't going to hurt me as long as I'm not dumb with them. I've overcharged them up to 4.35v, I've overdischarged, I've mixed cells in series, and done all sorts of dumb stuff, but the thing that will get you hurt with these is a short circuit. I don't know if you've done it yet, but things get very hot very fast. The ability to dump a lot of current is dangerous, regardless of the source.
The good cells are not likely to explode and would take a lot of energy input to get to that point anyways. I can't remember where I saw it, but I think it was Panasonic that had tested their cells with a ridiculous amount of overcharge voltage and overdischarge current (short circuit) and there were no catastrophic failures. The thing that worries me about the cheaper cells (some of the Ultrafire, etc.) is that they have no safety mechanisms in place, along with being made out of questionable materials. Some of the Ultrafire cells have shown to be smaller sealed cells sealed inside of a larger canister with powder taking up the rest of the space. To me, that seems like a recipe for disaster.
I'll share this story again: I was with Vinh testing a few tweaks to the TK61 buck drivers and his ring shorted across the TK61's battery carrier with (4) VTC5s in it. The period of contact was around 0.5 seconds but in that amount of time the ring glowed bright red and burned his finger pretty bad--instant smoke and dead skin. If it would have welded itself to the ring it would have been a big problem.
That’s a little less vague. I’m not sure I’ve heard that IMR doesn’t have thermal runaway though? That doesn’t sound accurate to me. AFAIK IMR is marginally safer at best. Using these cells without extensive health monitoring is playing with fire IMO. There’s nothing wrong with playing with fire, just don’t start a discussion about safety in the middle of it.
In any case you’ve really got to question who you put your trust in here. Unless I see specific claims from the manufacturer or tests from a trusted forum member I do not assume that a particular cell resists overcharging.
(As to considering something “safer” because of it’s lower energy density… maybe we should just stop this conversation. Or replace your battery with a rock. That should be safe.)
I agree, cells without a PTC or CID are a real concern: definitely a no-go.
Also, IIRC the battery recalls are generally due to manufacturing errors. As you mentioned these cells are capable of releasing very large amounts of power. IMO a manufacturing error(s) could easily defeat the safety mechanisms we rely on to protect us, chemistry doesn’t really come into that discussion.
so in your opinion, a IMR/INR/IFR is realistically no different than a LiCo? (other than the amp ratings of course)
I am careful with everything, but I try to cover all my angles and I figured i could rest easier with a so called “safer chemistry” in my lights (or at least the ones that don’t fit protected cells)
So if i have good quality cells (samsung, panasonic, sanyo) and take care of them, i’ll be fine.
Unless you go to LiFePo4 my opinion is that there isn't a big enough difference to worry about.
The lines between the different ICR/IMR/etc. chemistries have been blurred so much that it is really hard to make a judgment call based on a cell labeled as ICR/IMR/etc.
Yes Richard - it was Panasonic. It is in one of their datasheets but I cannot remember where.
As for people asking about the Enova - true that are not the 25R but they ARE a decent battery as I have a few.
For safety - there is no such thing as a "safe" battery - no matter what the chemistry. They ALL hold energy and can all explode if handled/used improperly.
Yow, I thought only big lead-acid batteries could pump enough amps to do that!
Out of curiosity I short-circuited a car battery with a thick insulated wire. Even just a split second of contact made it too hot to hold (through the insulation) and made the wire physically jump.
Not surprising, from a battery rated to put out kilowatts of power. It probably would have melted the wire if I held it on; I’ve heard of people melting whole wrenches in half by accidentally dropping them across the battery terminals.
I have done that to some of my tools. That's also another reason why I never wore jewelry (mechanical problems can rip a finger off and electrical will at best give a permanent wedding band and in some cases burn a finger to the bone.
Taking apart many of these laptop pulls I found out the hard way how much current is flowing through these Li-ions - and I am referring to an individual cell not multiples. When one sees a battery can cause wire to flame up it changes one's perspective.
I wonder how many of the Lithium Ion battery “failures” are actually electronics failures on devices they are installed in causing the battery to be shorted. If no proper fuse installed in the line from battery/batteries to the device electronics a short developing in the electronics could have very bad results. How many cheap Lithium Ion powered devices do not have proper fusing, including many flashlights.
What Wight explained as been my experience as well. Sometimes the traces act as a fuse, but when those don't usually a wire desolders itself before things get too out of hand. Unbraided springs overheat and collapse.
I would love to put some small fuses on some of these lights, but the problem is that even the best ones add resistance and would work against all of the efforts we make to increase output.
Yes, but they are very tight on the protected Panasonics. You have to put them in there just right, but they do fit. The ones I sell individually are the same as the ones I ship the cells in.