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I keep an Altoids tin boo boo kit in my laptop bag. A couple of bandaids, blister pads, a couple of Alieve, immodium and Sudafed. I have used it many times. I once went to a client meeting with a female colleague and as were standing in the lobby she realized her leg was bleeding from her morning shave. When I whipped out an alcohol prep pad and bandaid from the Altoids tin she was surprised but happy
Cool. I’ve got one too. In the origial vid you looked much younger, and I know YT has a lot of kids playing with airsoft guns and tactical nylon on there, lol.
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Gear – The Stuff We Carry Flashlights & Other Illumination DevicesAre you a current member with account or password issues?
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Dismiss NoticeLi-Ion Safety while charging and using these cells
Discussion in ‘Flashlights & Other Illumination Devices’ started by SilverFox, Mar 23, 2007.
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1 2 Next >SilverFox
SilverFox Empty PocketsJoined:
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5Jon asked me to drop by and see if I could answer some questions about Li-Ion safety.
Li-Ion cells are very simple to take care of. As long as you follow the basic rules, they give wonderful performance.
However, step outside the rules and they have the possibility of rapid disassembly, more commonly known as rapid venting with flame.
When using the Li-Ion cells that we have access to, limit the current draw to 2C. I prefer to use the actual capacity. Others go from the labeled capacity. I have run into situations where if you go by the labeled capacity, the cell will be good for around 10 cycles until it drops to 80% of its original capacity and is considered used up.
If you use a cell beyond its capabilities, it heats up. When the cell temperature exceeds 140 F, damage is done to the cell. If you continue to push the cell, thermal runaway is possible. The best indicator to tell if you are pushing things to hard is to check the temperature of your cells after using them.
Li-Ion cells have a usable voltage range from 4.2 volts down to around 2.5 – 3.0 volts. At high current draws (1C – 2C) you can run them down to 2.5 volts. At lower current draws, it is better to terminate the discharge at 3 volts. The Li-Po high current cells are terminated at 3.3 volts, and the voltage will quickly rebound to 3.7 volts open circuit resting. A cell at 3.7 volts is considered discharged. Our Li-Ion cells usually will rebound to above 3.0 volts.
If you over discharge a Li-Ion cell, damage can happen. This won’t be apparent until the next charge cycle. If dendrites and crystals pierce the separator, the cell can short out during the next charge cycle. Often, an over discharged cell can be recovered, but it is risky. Many times the cell will have increased internal resistance, and have less capacity. The proper way to recover a cell that has been over discharged is to immediately charge it at a slow rate (around 100 mA) to gradually bring the voltage up to over 3.2 volts. Once you are above 3.2 volts, you can do a normal charge. The amount of damage is proportional to the length of time the cell remains in the discharged state. All cells are not created equal, and some handle over discharge better than others.
It is best to recharge often and never get into a situation where you are over discharging your cells.
Some cells have a fall back protection circuit. This is designed as a last stand against over discharge your cells. If your circuit fails to shut off at the right voltage, the protection circuit is a last stand against deep discharge. Please note that the protection circuit should not be thought of as a safe level to discharge to every time. Recharge often and don’t run your cells into the ground.
Charging is where there is the most potential for explosive action. Never charge Li-Ion cells unattended.
What was that again? NEVER CHARGE LI-ION CELLS UNATTENDED!!!
Set up your charging area to eliminate combustible materials. Charge outside if you have to.
When a Li-Ion cell explodes, it reminds me of a road flare. It doesn’t last as long, but there are flames coming out and sparks flying everywhere. Lots of smoke and fumes too. I am not interested in lighting a flare in my house, and so I take a lot of precautions to make sure that if something does go wrong it is contained in a reasonable manor.
The charging algorithm for Li-Ion cells is refereed to as Constant Current/Constant Voltage. The cell is charged at CC until it reaches 4.2 volts. Then the current is tapered off as a CV of 4.2 volts is maintained. When the current drops to around 50-100 mA, it is shut off. Constant trickle charging is dangerous for a Li-Ion cell. The precision required from a Li-Ion charger and the CC/CV method with charge current shut off at the end, make the charger a little complex and the price of a charger can reflect this.
Charger manufacturers realized that it is a lot cheaper if they eliminate the CC phase and just let the charge taper off using the internal resistance of the battery to limit the charge voltage. These chargers generally charge at lower rates, but can charge cells to voltages higher than they should.
Charging a cell to 4.200 volts should give you around 300 cycles. If you increase the charge to 4.3 volts, you reduce that to around 30 cycles. If you lower it to 4.1 volts, your good for around 1500 cycles. It is far better to slightly undercharge than to overcharge.
Trickle charging is bad for the cell. The battery manufacturers recommend a charge rate of between 0.5C and 1.0C. Faster charging rates can damage the cell and may cause it to rapidly vent with flame.
A 1C charge rate will take around 1.25 – 2.0 hours to charge. If your cell takes longer than this, it is damaged. When the cells capacity drops to below 80% of its initial capacity, it should be recycled.
The RC people discovered that cells can go out of balance when charging cells in series. There have been fires that have resulted in damage to houses, garages, trailers, and cars. To avoid this problem, they have taken two approaches. One is to use a device that balances the cells during the charge. The other is to charge in parallel.
Taping the cells to monitor each cells voltage insures that no cells will be overcharged. This is a good way to go, but you need to wire taps to each cell and hook up a balancer to your charger. Some chargers have balancers built in, and some need an external balancing circuit.
If the cells are within 0.5 volts of each other, they can be paralleled together and charged as a large single cell. This limits the voltage to 4.2 volts, and the charge current depends on the smallest capacity cell in the group you have paralleled together.
There is an instantaneous transfer of energy when hooking cells up in parallel. The highest we have been able to measure is a very brief pulse of around 5 amps. This was with a fully charged battery pack hooked up to a fully discharged battery pack. If you can keep the voltage differences to 0.5 volts difference, or lower, that surge is greatly reduced. I have been using this method for over two years now, without problems. The disadvantage is that if you hook a number of cells in parallel, you need a charger capable of high currents to charge them. I generally do a pair of cells at a time just to keep things simple. My Schulze is capable of charging at 5 amps, and that is about right for 2 18650 2600 mAh cells. I also have a 10 amp regulated power supply that would allow me to charge 4 cells in parallel if needed.
I might add that it is very important to never charge Li-Ion cells unattended.
These are the basics. To pick a charger, look at the capacities of the cells you have and find one that allows you to charge at a proper charging current. Test the charger to make sure it does not overcharge your cells. If charging in series, keep in mind that cells can go out of balance and cause problems. If charging in parallel, be mindful of the transfer of energy when you hook the cells up. Try to only parallel cells that are close in voltage to each other. Clear your charging area of combustibles, and always charge your cells attended. If things go south, a bucket of sand is handy for suppressing the fire at the cell, and a fire extinguisher works well for putting out the fires started by the flying sparks.
If you follow all the rules, chances are very good that you will never have a problem. I caution people to not be afraid of Li-Ion cells, but to treat them with they respect they deserve.
Tom
#1 SilverFox, Mar 23, 2007
ProjeKtWEREWOLF, aih, batteryguru and 1 other person like this.
tvodrd
tvodrd Empty PocketsJoined:
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4:bow: :bow: Tom, for that!! I’ve been fortunate to not having an “adverse event” (Except for a few tossed on the coals of the BBQ out in the desert. ;D ) Bunch of Newton-Meters in a small package!
Larry
#2 tvodrd, Mar 23, 2007
greenLED
greenLED Empty PocketsJoined:
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20Excellent post, SilverFox. I’m very glad to have you around EDCF.
I’ve read of a couple of DSD Charger-related failures. In your opinion, is that a reliable charger to use if you have a couple of different sizes of cells? I understand I shouldn’t mix and match cell sizes/capacities while charging. I also have a new-gen Pila charger (thanks, JSB!) that I’ve been using. Is this better than the DSD?
Thank you.
#3 greenLED, Mar 23, 2007
SilverFox
SilverFox Empty PocketsJoined:
Nov 9, 2006Messages:
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5Hello greenLED,
I don’t have a DSD charger, so I can’t comment on it.
I do have the Pila ICB charger. I use it a lot and highly recommend it.
Of course, the Schulze greatly reduces the need for other chargers… 🙂
Tom
#4 SilverFox, Mar 23, 2007
Luxbright
Luxbright Empty PocketsJoined:
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0Hats off to you, Tom. O0
#5 Luxbright, May 25, 2007
petebroccolo
petebroccolo Empty PocketsJoined:
May 27, 2007Messages:
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0Thanks for posting this thread, SilverFox – I have made a copy and will send it along with my other files when my partners ask my advice on illumination tools.
#6 petebroccolo, May 29, 2007
WolfAmmoMan
WolfAmmoMan BannedJoined:
Jul 14, 2008Messages:
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0Thank you for this wealth of information ! O0
#7 WolfAmmoMan, Jul 15, 2008
Gryphon
Gryphon Loaded PocketsJoined:
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1I’ve heard of rechartgeable LIon cells over the last year or so, but always wondered if it was worth it. TBH, based on your excellent writeup, it really seems like it’s not. Aside from the reusability aspect, which of course has a certain appeal for cheapness and pollution reasons, is there a benefit to these cells? Are they higher-output than the equivalent disposables, for example, assuming nothing goes wrong?
#8 Gryphon, Jan 21, 2009
phoenix.stu
phoenix.stu Loaded PocketsJoined:
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0Very well put. I have several R/C vehicles and I have a couple that I am thinking about converting to Li-Ion. I have read several articles however, not quite so in depth and precise. This is very useful information. Thank you for sharing. O0
#9 phoenix.stu, Jan 31, 2009
SilverFox
SilverFox Empty PocketsJoined:
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5Hello Gryphon,
The advantage of Li-Ion cells is that one Li-Ion cell replaces 3 NiMh cells as far as voltage goes. This allows for small powerful packages.
It’s kind of hard to stay away from Li-Ion cells because they are used in cell phones, computers, cameras, and so on. The key to safely using them in flashlights is to understand their strengths and weaknesses.
Since most flashlights don’t have the same protection circuits that cell phones and computers have, you have to check things yourself. Having and understanding how to use a voltmeter are important, and having a quality charger eliminates a lot of the safety issues.
Anytime you store energy there is some risk. You would be surprised what a NiMh cell can do when it gets overcharged, but with some of the Li-Ion chemistries you have the flamability of the electrolyte issue. I fully understand your reluctance to use Li-Ion cells, but it is possible to safely use them, and safely charge them.
Tom
Yea. A coworker asked me what os would I choose now that I have used both. I said I’d def go android just because of the customization features you can do out of the box. Without root or in apple terms jail breaking.
Sent from a Samsung Phone. Apple don’t sue me!!
Very well put. I have several R/C vehicles and I have a couple that I am thinking about converting to Li-Ion. I have read several articles however, not quite so in depth and precise. This is very useful information. Thank you for sharing. O0
I carry a basic kit in my pocket organizer in a small ziploc bag. It contains:
– steri-strips
– 2×2 gaize
– a few various size bandaids
– blister cover
– individually wrapped topicals – iodine, alcohol, antibiotic ointment, burn gel, calagen (anti-itch)
– single dose of otc – antihistamine, anti-diarrheal, antiacid, goodys
I also have a separate mini trauma kitIf your looking for a ready to go kit, Adventure Medical and Rescue Essentials have some good small ones.
jda said: ↑
This is how I store my truck gun, I’d have done the vid from the jeep if I didnt think it would scare the :censored: out of the neighbors.
Click to expand…
Was that real, or was it airsoft?I’ve heard of rechartgeable LIon cells over the last year or so, but always wondered if it was worth it. TBH, based on your excellent writeup, it really seems like it’s not. Aside from the reusability aspect, which of course has a certain appeal for cheapness and pollution reasons, is there a benefit to these cells? Are they higher-output than the equivalent disposables, for example, assuming nothing goes wrong?
I recently upgraded from my iPhone 3GS to a Samsung Galaxy S3 on AT&T. My friends (all Apple fans) asked why I didn’t wait for the iPhone 5. Oh look, the iPhone 5, playing catch-up with all the Android devices. I haven’t been impressed by an iPhone since the 4.
Resistance is futile, you will be assimilated into the Google collective.
While it does contain a few trauma items, I do keep a Personal FAK on hand in my EDC bag, along with a more specific Trauma FAK as well.
Looking for thoughts or examples on the simple ‘boo-boo’ kits people have, not for trauma or heavy wilderness care. We’re talking for around the office or out and about, minor ouch moments or nice things to have in case of an itch or scratch. Looking for nice things to keep on hand, ideal soft containers that keep things organized, and ideally in a bright color that doesn’t scream trauma or emergency?
