LuxLuthor said:Andrew, I just don't think your assumption that charging Li-Ion cells in S4-P1 or S4-P2 will not result in a fire....because you have not heard of such an event is smart in the face of so many examples in the RC LiPo world. We know it has happened with free cells on airplanes. We know it happens with laptop packs that are not abused like the RC users. We know it happens with the non-rechargeable 123's. We know there are strict warnings given about maximum charging voltage cutoffs. We know chargers have cutoffs typically at 4.2V.
All of that suggests a stronger case for the real danger, than your speculative arguments that it is overstated and overblown.
I don't think you can be sure of your voltages coming closer into balance response to SilverFox unless it is specifically tested. The cells in a FM pack are touching the other cells on two sides. You honestly don't think there would be enough heat/damage from one cell exploding/catching fire to cascade the other three, while contained inside of a Maglite tube? I do.
Now, about my own failure to find out about the Lithium charging guidelines. Guilty as charged. I again remind you, that NOTHING was stated as a warning on AW's GB thread, nothing on Alin's charger GB, nor the plain box, nor in AW's DSD charger GB, nor the DSD's plain box, nor the Pila site where I chose the battery sizes I wanted, nor in the box with the Pila charger, nothing in any of FiveMega's GB threads that used Li-Ions, and linked Alin's charger, nor from you when I got the unprotected 4S Mag66, nor a warning of a danger of fire or explosions with my cell phone or laptop battery.
I heard about the Sony Laptop battery recall, but figured it was totally related to a mis-wired battery holder, or some bizarre manufacturing defect. It never occurred to me that there might be an inherant risk in the entire Lithium battery technology that was not present with Lead Acid, NiCad, or NiMH.
I also never thought that Maglite mods, Li-Ion batteries, and Lithium chargers would be sold here without a clear, obvious warning being stated in the GB threads that would have caught my attention. I guarantee I am not the only one who has missed this danger, and how to use Lithium batteries safely.
LuxLuthor said:
SilverFox said:Hello Andrew,
I am sorry if you don't understand how Li-Ion cells work. The example I gave is exactly how it works. Li-Ion cells have no ability to withstand an overcharge and can not be balanced through peak charging.
When Li-Ion cells are completely discharged the cell to cell imbalance will be greater, but if you look at the example you will see that some of the cells were nearly fully charged. These cells have nowhere to go but up to a higher voltage.
The RC people do push the limits, but there is a lot of them that work within the limits too. When these people report their packs catching on fire, I take notice. When they report that their packs have gone out of balance and the packs puff and blow while charging, it is enough evidence for me.
Your theory is wrong. There are a whole bunch of people with burned up trailers, shops, cars, and houses to prove that it is wrong.
If you tell others that Li-Ion cells will self balance, you are wrong and this is a very dangerous thing to do. People listening to your theory will end up having problems, which may include fire damage.
If you want to play with fire, please do so by yourself. Please don't bring unsafe and unsound charging methods forward and encourage others to follow them.
Tom
awr said:Maybe i should call it the 'middle-class' M6 :-D (the prototype maybe cost $130-150 including all the various parts).. i'm hoping if i get it to a turnkey that i can sell them for at about 1/2 the price of the M6, just starting to explore cost-saving options.. the light doesn't have the shock isolation of the M6, but the beam is much whiter and brighter. I just upgraded the battery pack to use 14650s (i think i mentioned that).. but it's a huge deal because it means the cells are only pushed to 2C not 2.6C which i would not recommend anybody copy.
LuxLuthor said:No. Almost all the packs that are being made for these flashlights and spotlights are using Li-Ion cells such as the ones being sold here. RC Lithium Polymer LiPo packs such as the one cell seen here use a number of an even less safe, more fragile type of cell like this one that are soft and lacking the hard metal case of a Li-Ion cell.
chasm22 said:Lux,
I think you're being a little disengenous in your assertions about being unaware of the dangers. This is a direct quote from you in a thread you started almost a year ago to the day, "Yeah, after reading about the issues of Li-Ion/LiPo charging, storage, and care....I totally agree with you on needing to be very careful and more conservative when dealing with them." (Emphasis mine)
If you want to lead the charge now for safety issues as they pertain to li-ions, be my guest. It would seem that you are(and have been)quite well informed on the issues involved.
Chuck
VidPro said:i dont think one as being "safer" than the other
the canned cell has a projectile, or rocket, and the bagged cell can be damaged easier.
a GOOD canned cell built to U.S. (overly protective) specs should be safer, because it has the facility to have a anode disconnect. but when there are incidents CLAIMED to be due to extra lithium metals, its CAN structure can move further when ignited.
Protection for bagged cells doesnt run the opposing pole of the battery right next to the other pole.
its a tossup, if there was a most critical factor its the HUMAN and how the human uses it, and pushes it.
take 50,000 toy playing humans trying to get to play with thier toys faster, and some human is going to fall off thier skateboard.
LuxLuthor said:I did a search to see what was the source of my Alzheimers...and to see how out of context your accusations were...and LOL! sure enough, you pulled that brief comment out of 3 pages of posts from this thread
LuxLuthor said:
You should be proud of yourself, chasm22, you did a real public service today !!!
LuxLuthor said:I have an extra battery pack from my BarnBurner that I carefully peeled off layers to confirm that these are using 4S-3P of 12 Samsung Unprotected 18650 cells. As far as I know, this pack has never been used, and I charged it one time about 2 months ago.
The pack voltage gives 16.55V and fortunately each of the cells gives a reading between 4.13 - 4.15V, but again an imbalance would only develop over repeated discharge and charging. There are no individual cell taps for balancing this pack.
Click on each thumbnail image for larger view.
SilverFox said:Hello LuxLuthor,
Kevin was pointing out that notebook computer battery packs do not balance each cell within the pack. They check for a difference between strings.
This is not a bad way to go, if you limit the depth of discharge and charge a little sly of 4.2 volts. Individual cell balancing is ideal, but this isn't a bad compromise.
Tom