18650 battery?

[geronimotwo]

has anyone used these?  are they worth changing platforms (from AA)?  from what little i can gather they are similar in size to a AA, but are 3.7v with higher mAh.  can anyone confirm this?

[mtnbkr]

They're a good bit bigger than AA.  Most of my flashlights use them (with light heads that'll support 2xCR123 as well).  I like them well enough.

Chris

[Hutch]

G2, given how good the current crop of high tech LED's are, and how many of those run on AA's, I've decided to simplify my logistics by switching out everything I can to AA's.  The onliest thing I'm stuck on is a replacement for the Streamlight M3's, which require CR123's, and for which no good replacement is known to me.

Also, given the current technology with low self-discharge NiMH rechargeable batteries, AA form factor gets even more attractive.  Sanyo Eneloop and a Maha smart charger.  That's the ticket.

[AJ Dual]

Probably the best rechargeable cells out there. They get all the R&D because many laptop batteries are comprised of them. Pilas and Panasonic are some of the best.

[Marnoot]

I started the switchover to using 18650 batteries when I got my Jetbeam BC40 as it either takes 4xCR123 or 2x18650. I'm very happy with them, excellent runtime compared to a AA-batteried light of equivalent brightness and much cheaper in the long-run than stocking up on CR123s. Some CR123-based lights do not accept 18650s, just make sure that your light of choice does. Downsides to 18650 being that replacement batteries certainly are not as easy to come across as the super-standard AA/AAA/etc type, and that there will be a slightly painful initial investment in the charger (if you get a good one, which you should).

One important point to make: If you decide to go with 18650 batteries, do not cheap-out on either the batteries or the charger. Some barebones, super-cheap 18650 batteries do not come with built-in protection circuits which are mandatory for lithium batteries, unless you like lithium fires in your pocket. It's also important to get a good charger to prevent over-charging (again with the fires). I use AW IC batteries, charged in a PILA IBC charger. Candlepower forums is a good place to research the various well-known, reliable offerings of both batteries and chargers, and known-good combinations thereof.

[zahc]

You would need to come up with a good explanation for me to understand the point.

I understand that alkaline AAs are wimpy batteries, but eneloops change everything.

I guess I can see 18650s for large, very bright, professional-use type of lights. For any EDC/pocket light, AA is the way.

[Hutch]

Disagree, Zahc.  Alkaline AA's are as common as gravel, relatively cheap, almost invariably of acceptable quality, and have an enormous range of applications.  What's not to love?  To these attributes, one can add the availability of very high capacity NiMH AA batteries, that have the storage capacity, up to 2500 mAH, of a common D cell, rechargeable up to 1000 times.  Get 'em.  Use'em.  Love 'em.

[birdman]

Oh, surefire now has approved rechargables for their CR123 flashlights.  This should simplify things greatly.

[zahc]

Disagree, Zahc.  Alkaline AA's are as common as gravel, relatively cheap, almost invariably of acceptable quality, and have an enormous range of applications.  What's not to love?  To these attributes, one can add the availability of very high capacity NiMH AA batteries, that have the storage capacity, up to 2500 mAH, of a common D cell, rechargeable up to 1000 times.  Get 'em.  Use'em.  Love 'em.

You must have misunderstood my post. I was advocating AA. AA alkaline batteries are wimpy and cannot drive significant current (though this is less important with LED lights anyway), however, the existence of eneloop-type Nimh batteries changes everything and makes the AA format attractive again for high-performance flashlights. Given the existence of lithium-chemistry AAs and eneloops, any other format would have to have substantial advantages to be worth giving up the advantages of the AA size.

[Hutch]

Oh.  Sorry.  Hutch - often wrong, seldom in doubt.

[AJ Dual]

You must have misunderstood my post. I was advocating AA. AA alkaline batteries are wimpy and cannot drive significant current (though this is less important with LED lights anyway), however, the existence of eneloop-type Nimh batteries changes everything and makes the AA format attractive again for high-performance flashlights. Given the existence of lithium-chemistry AAs and eneloops, any other format would have to have substantial advantages to be worth giving up the advantages of the AA size.

2600 to 3100 mAh at 3.7V is going to be the major advantage of an 18650 over an LSD AA NiMh which will give you 1.2V at 2000 mAh, best case scenario.

Add to that, if it's an LED light with A forward Voltage of around 3.5-4.5VV, the two 1.2V NiMh's are only producing 2.4V total, and the LED light's driver is going to have to work harder in boost mode, which will reduce your efficiency even further. Of course, any quality LED drive will have a driver circuit that will always be causing some losses as it does voltage and current regulation up or down as needed.

The sheer convenience for the back-end logistics of AA's is great. OTOH, if the light is being used for something where you just can't drop what you're doing to change batteries, the extra capacity of an 18650 is going to be appreciated.

[zxcvbob]

I saw a package of 18650 batteries at Walmart in the clearance aisle for $5.  I started to get it, not sure if my CR123 flashlight can use them or not but it would be fun to try.  I don't remember what brand; some big name electronics company that you normally don't think of making batteries --like Sony.  Looked at the fine print on the package and they were only 500mAh capacity.  Needless to say I didn't get them.

[bedlamite]

I saw a package of 18650 batteries at Walmart in the clearance aisle for $5.  I started to get it, not sure if my CR123 flashlight can use them or not but it would be fun to try.  I don't remember what brand; some big name electronics company that you normally don't think of making batteries --like Sony.  Looked at the fine print on the package and they were only 500mAh capacity.  Needless to say I didn't get them.

Are you sure they were Li-ion, ore were they LiFePO4? Right now they have about half the energy density, but no fire hazard and a much longer lifespan. Either way, 500mAh seems low.

I've been using these for about 2 years now with zero problems. When it's time to replace them, I will probably get LiFePO4

[AJ Dual]

Are you sure they were Li-ion, ore were they LiFePO4? Right now they have about half the energy density, but no fire hazard and a much longer lifespan. Either way, 500mAh seems low.

I've been using these for about 2 years now with zero problems. When it's time to replace them, I will probably get LiFePO4

That sounds as if they were probably 16430's... 500-800 mAh is what they hold. And those are still bigger than AA's, so would be easy to mistake for 18650's unless you saw them side-by-side. (BTW, these numbers mean "16mm in diameter, 43mm long... 18mm in diameter, 65mm long etc."  Even a LiFePO4 that was 18650 size would be at least 1000 mAh I'd think.

You could technically call an AA battery a 14500, and you might even see them called that somewhere in the fine print on a blister pack of them... but nobody'd know what the hell you were talking about.  

[Marnoot]

Another thing to keep in mind is that bare 18650s without protection circuits will be 18mm X 65mm, but batteries with protection circuits will vary in size depending on who made them. For instance an AW IC branded 3100mah cell is 18.52mm X 68.16mm, while an Orbtronic branded one is 18.4mm X 68.9mm.

There is no standard size for for an "18650" with a protection circuit, and thus no guarantee that Protected 18650 X will fit in Flashlight Y. Always good to have somewhere the measurements of your flashlight's battery compartment, and those of the battery you're considering, or use other people for guinea pigs and read in forums what combinations work.

[geronimotwo]

wow, candlepowerforums has all kinds of info (boy do THEY have way to much time on their hands ).

Another thing to keep in mind is that bare 18650s without protection circuits will be 18mm X 65mm, but batteries with protection circuits will vary in size depending on who made them. For instance an AW IC branded 3100mah cell is 18.52mm X 68.16mm, while an Orbtronic branded one is 18.4mm X 68.9mm.

There is no standard size for for an "18650" with a protection circuit, and thus no guarantee that Protected 18650 X will fit in Flashlight Y. Always good to have somewhere the measurements of your flashlight's battery compartment, and those of the battery you're considering, or use other people for guinea pigs and read in forums what combinations work.

i had no idea the sizes are marked that way.  i also hope that the batteries i bought fit in the light if they vary that much.

[Marnoot]

wow, candlepowerforums has all kinds of info (boy do THEY have way to much time on their hands ).

That's an extremely apt description of that forum. Super informative, but you often have to deep-dive through the mass of information to get what you need. All kinds of geeks in the world: sci-fi geeks, gun geeks, sports geeks; that there forum is the prime hive of flashlight geekery.

i had no idea the sizes are marked that way.  i also hope that the batteries i bought fit in the light if they vary that much.

I think generally most flashlights have enough give either in the battery spring, or the battery cap position to accommodate the minor variations in battery length. There are a few outliers where you get a flashlight with a very tight compartment and a battery that's extra long, but I think the odds are that you'll be fine.

[zxcvbob]

I've got a bunch of cheap LED flashlights that use 3 AAA batteries in a carrier that measures about 21.5 x 50mm.  At least one of them has a long spring and *might* have enough room to use a 18650.  I've also thought about shimming a CR123A and putting it in there, but the voltage is probably too low.  (a rechargeable's voltage is probably just right)

Also I have one flashlight that uses CR123A's, but I don't remember how many.  If it uses 3, I could maybe replace them with 2 longer rechargeable cells and the voltage would be close enough.

The trick is how to charge them.  I wonder if you could use a temperature sensor to detect when the battery is full and shut down the charger?

[bedlamite]

The trick is how to charge them.  I wonder if you could use a temperature sensor to detect when the battery is full and shut down the charger?

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries/

[zxcvbob]

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries/

Thanks.  From a superficial look at it, maybe all I need is a power supply regulated to 4.00V (current limited to 1C or less) and it doesn't need a shutoff because you can't overcharge at that voltage.  Will have to study it some.

[bedlamite]

Thanks.  From a superficial look at it, maybe all I need is a power supply regulated to 4.00V (current limited to 1C or less) and it doesn't need a shutoff because you can't overcharge at that voltage.  Will have to study it some.

Don't do that when a decent charger is this cheap: http://www.dealextreme.com/p/ultrafire-all-in-one-18650-14500-17500-18500-17670-batteries-charger-94444?item=28

And the consequences of screwing up can be bad: http://www.youtube.com/watch?v=HCGtRgBUHX8

[AJ Dual]

Don't do that when a decent charger is this cheap: http://www.dealextreme.com/p/ultrafire-all-in-one-18650-14500-17500-18500-17670-batteries-charger-94444?item=28

And the consequences of screwing up can be bad: http://www.youtube.com/watch?v=HCGtRgBUHX8

That was most likely a LiPoly pack, they're even more energetic when things go bad. A LiOn isn't quite as awful.

But yeah, any Lithium chemistry battery going critical is generally pants filling for sure. 

[bedlamite]

Yeah, LiPolys go up in flames easier, but the end result is the same.

[Marnoot]

I tend to shy away from Ultrafire stuff. Worth reading:

http://www.candlepowerforums.com/vb/showthread.php?280909-Ultrafire-18650-3000mA-exploded

Cheap chargers tend to be more likely to overcharge, especially when charging in pairs. Overcharging is likely what caused the above linked explosion.

[zahc]

Battery splosions are very bad if they happen when the battery is installed in a light, especially with high-quality flashlights, which are made of stronger materials. You basically have a pipe-bomb in your hand.