18650 batteries

[zahc]

I have a charger already, but no cells. I have a couple cheap flashlights that take the 3xAAA adapters but I think an 18650 would fit. I have no need for high amperage, but I would like them to be safe and have low self discharge if possible. Something I could be a good fit for a nicer 18650 light if I ever get one. Thinking about picking up some Samsung cells on Amazon like this. Thoughts?

https://www.amazon.com/gp/product/B075YNR6VY/ref=ox_sc_act_title_2?smid=A314KTEZP2WKCH&psc=1

[zxcvbob]

I recently bought one of these:  https://rtdelectronix.com/panasonic-ncr18650bf-3400mah/ and a pair of these:  https://rtdelectronix.com/samsung-inr18650-25r-2500mah-green/ and have been very happy with them. I'm using them in a flashlight that probably draws about 2 amps.  I did have to make a little button-top adapter to get them to work, even tho' I was using recycled flat-top cells before without any problem w/o an adapter.  The old batteries' top terminal was flush with the top.  These were actually recessed slightly.  (the ones you linked look that way too; that's probably how they are supposed to be)

I assume all batteries sold on Amazon or eBay are counterfeits.  They might still be good batteries but probably don't meet their rated specs.

I'm charging them with one of these https://www.rtdvapor.com/xtar-vc4/ and my wife's iPad charger.

[Hawkmoon]

They might work, but for flashlights you really should have button top, not flat top.

I bought these: https://www.amazon.com/gp/product/B076CCV2NV/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1

They're no-name batteries, but that's what you'll get when you buy "Samsung" batteries from Amazon anyway. I've had them for about six months and they're okay so far.

The 18650s are also smaller in diameter than those triple-AA magazines, so you'll need sleeves to locate the battery.

[zxcvbob]

An 18650 is too long for many 3-AAA flashlights with the plastic battery holder; it will work in some.  If it's too long, you'll have to use 18500's.

[Calumus]

RTD is going to be tough to beat price wise, and everything he sells is authentic. Full disclosure, he is a client of mine; but I bought from him exclusively for a couple years before I started working with him. Counterfeit batteries could be OK; but they also could melt down the first time you throw them on a charger. Why risk it over a couple of cents? He also has a decent selection of flashlights as well.

[bedlamite]

Good prices, fast shipping, no fakes:

https://liionwholesale.com/

[K Frame]

I have one LED flashlight that came with the 3 AAA plastic battery carrier, but it specified that it would also work with an 18650 battery pack.

This is a good article that I've turned to a couple of times for guidance.

https://www.makeuseof.com/tag/18650-battery/

[zxcvbob]

I have one LED flashlight that came with the 3 AAA plastic battery carrier, but it specified that it would also work with an 18650 battery pack.

This is a good article that I've turned to a couple of times for guidance.

https://www.makeuseof.com/tag/18650-battery/

Thanks for the link.

I did not know that the maximum sustained current was inversely related to the mAh rating.  But it makes sense when I think about it; thinner electrodes with more surface area give higher capacity, but also higher resistance so more heat.  (I don't know if that's how they work, but it's logical)  The 3400 mAh battery I bought is only rated for 4.8A.  The slightly cheaper 2500 mAh batteries are 20A.  My flashlight is less than 2A, so both are fine -- I lucked out.