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Old 10-10-17, 12:09 PM   #1
tyrion
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What's so special about 18650 batteries?

Why are they used so much in battery packs, as opposed to lithium ion version of traditional consumer batteries like AA and B, etc.?
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Old 10-10-17, 12:28 PM   #2
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Nothing special, except for the size.

The larger size means more capacity, analogous to using AA vs. AAA batteries. There's also a benefit to the size because larger batteries have higher capacity to weight ratios.

However, nothing stops you from using a pack of AA batteries if you can live with shorter run times.
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Old 10-10-17, 02:38 PM   #3
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Li-Ion equivalent AA is 14500 battery. I think the biggest capacity is about 840mAh. Compare that to 18650 which are well over 3000mAh and when you divide by volume of cell you see that 18650 is king.
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Old 10-10-17, 02:46 PM   #4
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Power to weight and size cannot be beat. All the others are far less powerful for the weight and size
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Old 10-10-17, 08:10 PM   #5
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Plus they're pretty inexpensive due to the high volume manufacturing.

They used to be used in laptops.
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Old 10-11-17, 05:24 AM   #6
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18650s are exclusively Lithium-Ion batteries, as opposed to AA or AAA form factors, which chemistry/energy density can vary.

As f4rrest points out the 18650 has become ubiquitous in electronics, it is the core cell in everything from laptops,E-bikes to Tesla electric cars. Therefore economies of scale of pushed price down resulting in high energy density at reduced cost.
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Old 10-11-17, 05:56 AM   #7
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While there are some Li cells in the 14500 AA size, these have the problem that people could easily mistake them for a regular AA cell and put them in devices intended for alkaline cells having a voltage of about 1.5V. The Li+ chemistry produces about 3.7V and could damage some devices made for the lower voltage. Better to use a different physical size to avoid such confusion.
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Old 10-11-17, 08:09 PM   #8
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While there are some Li cells in the 14500 AA size, these have the problem that people could easily mistake them for a regular AA cell and put them in devices intended for alkaline cells having a voltage of about 1.5V. The Li+ chemistry produces about 3.7V and could damage some devices made for the lower voltage. Better to use a different physical size to avoid such confusion.
And since Li-ion are rechargeable, and alkaline AAs are not, you could mistakenly put an alkaline battery on a charger.

Aren't 18650 also used in the 777? And Tesla is using an even larger battery in the model 3, the 21700, for even higher capacity. The models S and X use the 18650.
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Old 10-12-17, 12:35 AM   #9
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If you need some, just get them from an old laptop battery pack..... break it open and get a minimum of 8, buy a charger on amazon and your set.

Pete
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Old 10-12-17, 01:00 AM   #10
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If you need some, just get them from an old laptop battery pack..... break it open and get a minimum of 8, buy a charger on amazon and your set.

Pete
I don't know about you, but for me, the batteries are the first thing to go in my laptops. By the time I'm looking at a new laptop, the battery is down to a shadow of its new capacity and can hardly hold a charge at all. In fact, the one in my current laptop is so weak it can barely power it for 15 minutes. Needless to say, I'm shopping for a replacement, but don't see any reason to salvage the cells.
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Old 10-12-17, 08:50 AM   #11
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If you need some, just get them from an old laptop battery pack..... break it open and get a minimum of 8, buy a charger on amazon and your set.

Pete
Laptop cells are unprotected so be careful to make sure the device you put them in has built-in protection.
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Old 10-12-17, 11:17 AM   #12
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Each one is 3.7v, where rechargeable (A, AA, C, D ) are 1.2v, (single use alkaline are 1.5v)


https://www.batteryjunction.com/18650.html

milli Amp/hour, is the charge capacity, its akin to a gas tank volume, it depends on the rate of draw, the load.

Think rate, in amps, as; Geo metro vs Race-dragster V8.. little over a longer time, vs, a lot over a short time..




..

Last edited by fietsbob; 10-12-17 at 11:26 AM.
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Old 10-12-17, 12:05 PM   #13
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I don't know about you, but for me, the batteries are the first thing to go in my laptops. By the time I'm looking at a new laptop, the battery is down to a shadow of its new capacity and can hardly hold a charge at all. In fact, the one in my current laptop is so weak it can barely power it for 15 minutes. Needless to say, I'm shopping for a replacement, but don't see any reason to salvage the cells.
Not my case. I had a laptop with a good battery that wouldn't boot any longer. I took the battery apart and have like eight really good cells, I charge them with a recharger I bought online.
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Old 10-12-17, 03:02 PM   #14
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The really big difference is long-term cost. Most good Li-ion batteries can be recharged 300 times before dropping to 80% of the initial capacity at which time they should be replaced. This makes them far more cost effective in the long run.

I recently bought a pair of Panasonic 3400 mAh batteries for $11.50 a pair with free shipping. The first test was against two low-cost Trustfire batteries. One was labeled 4000 mAh and the other 5,800 mAh. This was in a dual CREE XPE LED bike headlight used on alternating LED flashing mode. It uses two 18650 batteries. The light ran 13 hours and 16 minutes before the low battery light began to flash. The Trustfire 4000 mAh lasted 3 hours 20 minutes and the Trustfire 5800 lasted 2 hours 4 minutes. All batteries were charged right before being used.

The light can also accept three AA throwaway batteries. There are many professional battery comparisons that you can look at. Two that seem easily understood are Battery Showdown — The Best AA Battery You Can Buy? — High Drain Test and Powerstream https://www.powerstream.com/AA-tests.htm The discharge in the British study was to 0.1V. Most bike lights would quit long before the voltage ever got that low. The prices for these batteries varies a bit depending upon how many you buy at one time from a single 4-pack to 24 pack. For Duracells it was $1.23 to $.58 per battery, Energizer max $.62 to $.99 and Energizer Ultimate Lithium $1.74 to $2.08. For some strange reason the 24 pack of the Energizer Ultimate Lithium was more for the largest pack and didn't go down much as the number in the package increased. A lot depends upon how many milliamps you draw. The higher the drain, the lower the ultimate output in mAh. The best battery was the Energizer Ultimate Lithium with a 2800 mAh capacity at a 2 amp discharge. The Duracell Coppertop battery only gave 540 mAh at that high a drain rate. A single CREE XML-T6 LED can use up to 1500 mA for maximum brightness according to the CREE website.

If you look at it simply from initial cost the three AA Duracell batteries cost $3.69 (plus tax). Just 3 sets of the Duracell batteries costs more than one set of the rechargeable Panasonic batteries.
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Old 10-12-17, 04:43 PM   #15
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Another thing that hasn't been mentioned is most newer/better lights are designed to use 18650 batteries.
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Old 10-12-17, 07:59 PM   #16
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I splurged and bought a pair of Orbtronics 3500mAh batteries at $30/pair. These are higher current than the 3400mAh types, even though the rating is only marginally higher. I haven't run either one down yet, so maybe this is a good purchase. I'll be using my lights a lot more now, although I also have a very good dynamo light on my commuter and won't be using batteries all that much anyway.
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Old 10-12-17, 08:44 PM   #17
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Originally Posted by FBinNY View Post
I don't know about you, but for me, the batteries are the first thing to go in my laptops. By the time I'm looking at a new laptop, the battery is down to a shadow of its new capacity and can hardly hold a charge at all. In fact, the one in my current laptop is so weak it can barely power it for 15 minutes. Needless to say, I'm shopping for a replacement, but don't see any reason to salvage the cells.
Normally it's just 1 or 2 bad batteries, I have always been able to salvage at least 3/4 of the batteries.

Just my 2 cents....

Pete
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Old 10-12-17, 08:50 PM   #18
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Normally it's just 1 or 2 bad batteries, I have always been able to salvage at least 3/4 of the batteries.

Just my 2 cents....

Pete
That's good to know. I may try it. But my main use for li Ion batteries is lighting, and high capacity is important to me. So I'd rather pay for a good battery than use a decent battery even for free.

Like some of the others here, I've found a material difference between quality branded batteries and bargain ones.
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Old 10-12-17, 10:55 PM   #19
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Normally it's just 1 or 2 bad batteries, I have always been able to salvage at least 3/4 of the batteries.

Just my 2 cents....

Pete
I took a failing pack apart and ALL of the batteries were usable. Bad controller.
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Old 10-13-17, 10:04 PM   #20
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Just be really careful when charging unprotected cell.

There's a horror story on candlepowerforums of a guy with permanent nerve damage from exposure to the fumes offgassed by an 18650 cell that caught fire indoors.

I also had a cheap 18650 cell spontaneously catch fire in a drawer.

I no longer use cheap chargers and only charge in the garage on a non flammable surface.
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Old 10-16-17, 08:51 AM   #21
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Just be really careful when charging unprotected cell.

There's a horror story on candlepowerforums of a guy with permanent nerve damage from exposure to the fumes offgassed by an 18650 cell that caught fire indoors.

I also had a cheap 18650 cell spontaneously catch fire in a drawer.

I no longer use cheap chargers and only charge in the garage on a non flammable surface.
Yes, and even if you're not worried about that there is no reason to take any risk at at all, nor waste time trying to re-purpose cheap 18650 cells. Battery packs are already good bargains, just recycle and buy a new one.
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Old 10-16-17, 09:34 AM   #22
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3 rechargable 1,2v in the space of one..


You Old enough remember the 4.5v oval/flat batteries that were the choice of French light companies, in the 80s?



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Old 10-16-17, 02:49 PM   #23
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[/IMG] Please provide a link to the story on Candlepowerforums where somebody posted about nerve damage resulting from a lithium ion battery. I checked the first 10 pages (there are a lot) in the section about batteries and there was nothing. It also doesn't make sense. If you had enough chemistry to understand what makes up one of these batteries you would come to that conclusion. There are just not enough chemicals in a single battery to cause major havoc. My heaviest 18650 battery (Panasonic) weighs 45 grams or 1.77 ounce. There is a carbon anode (graphite) core, a metal case and a separator between the layers of material making up the anode. These contain the lithium salts and electrolyte. There is just nothing in the list of chemicals used for the battery would cause nerve damage if it caught fire.





Here's a more likely scenario from someone who posted on the site:

I use Imr cells for vaping as well as flashlights. So I carry extra 18500s with me. I always put them in a case in my lunch bag. Well one morning after not enough sleep I just grabbed a couple extra cells and put them in my pocket which really is fine. Unfortunately later I threw a bunch of change in that pocket so I'm walking around and all of a sudden my pocket is about a million degrees. Quickly emptied my pocket on the floor and half the coins and the one battery were too hot to hold. And I've years of experience with these and know better but screw ups happen. Protected cells would've avoided that. But they can't provide 6a regular use either

These cells can cause a fire so they should be stored so as to never short out. It's not rocket science.
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Old 10-16-17, 06:51 PM   #24
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So what happens if the battery contains an additive containing fluorine which combines with hydrogen during thermal runaway? Which 18650's, if any, do or don't have this risk? If that happened I wouldn't want to breathe it.
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