Can I interchange 18650 batteries?

[tbone1004]

I like the knock-off ultrafires which I get for about 1 dollar each. They're my backups and for emergency/light use

get a charge me that actually tests cells and you’ll realize why those are only a dollar each...

To those looking at chargers. I highly recommend getting a charger that can test cells, especially if using batteries from shady manufacturers or anything with “fire” in the name that are usually taken out of old laptop battery packs. One like the Opus is really easy to use and can tell you what the actual capacity is vs whatever nonsense is out on the labels of most of those cells

 

[STIDVC]

get a charge me that actually tests cells and you’ll realize why those are only a dollar each...

To those looking at chargers. I highly recommend getting a charger that can test cells, especially if using batteries from shady manufacturers or anything with “fire” in the name that are usually taken out of old laptop battery packs. One like the Opus is really easy to use and can tell you what the actual capacity is vs whatever nonsense is out on the labels of most of those cells

Hence backup.

 

[HKGuns]

get a charge me that actually tests cells and you’ll realize why those are only a dollar each...

To those looking at chargers. I highly recommend getting a charger that can test cells, especially if using batteries from shady manufacturers or anything with “fire” in the name that are usually taken out of old laptop battery packs. One like the Opus is really easy to use and can tell you what the actual capacity is vs whatever nonsense is out on the labels of most of those cells

I'll put a finer point on that one.......Friends don't let friends buy China produced batteries, regardless of size. They don't meet their stated specs and are typically slightly above junk.

Buy Taiwan or Japanese produced batteries.

 

[bvanant]

In general I think that making sure your 18650 batteries are protected, we have seen numerous non-protected versions (for vaping) fail in quite spectacular ways. The Nitecore batteries that Backscatter suggests are quite good and are very close to their stated capacities when tested at 1A discharge with a reliable battery tester like

The Nitecores that I have are actually Panasonic cells with the Nitecore protection circuit. I have a number of *fire batteries that say they are protected but actually don't have protection circuits on them. I use the Nitecore USB chargers, slow as molasses but slow charging is good for batteries.
Bill

 

[fmerkel]

I like the knock-off ultrafires which I get for about 1 dollar each. They're my backups and for emergency/light use

I hope that's a joke. Ultrafires are a serious joke as batteries. Worse than a joke, potentially dangerous. Miserable capacity and short life.