18650 Batteries

[Rider]

Ok, I've seen a lot of vids on building powerwalls using 18650 batteries. I just thought 18650 implied LiFePO4 chemistry as well as the physical size. I ordered some LED wheel lights for my ride, and they come with 18650 Lithium Ion batteries. So now I'm thinking the 18650 is just the size format, not necessarily the chemistry.
LiFePO4 = 3.2V
Li-Ion = 3.7V

So here's my question: If you buy a bunch of these "18650" batteries thinking they are LiFePO4, how can you tell if you're getting the real thing, or a poor condition LI-Ion in a LiFePO4 wrapper? Even after recharging, a bad Li-Ion may only show 3.2V, so that's not a good check.

 

[SolarRat]

18650 is just the size: 18mm x 65mm. Makes it easy to find what size fits in small projects, ie: 14550 = 14mm x 55mm...which happens to be the same size as a AA, but 3.7v (useful to overpower some small flashlights).

I've been using 18650 Li-Ion for years, it was only recently I started seeing LiFePO4 18650's. Since I use them in high draw devices that fit in my pocket I only buy name brand cells so I know what I'm getting and don't have an explosion near my man jewels. Panasonic, Sony, Samsung, LG, Sanyo...anything else is a crapshoot. I'd probably follow the same rule if buying Li-Po's. I've never heard of anyone finding Li-Ions re-wrapped as LiFePO's...but ya never know.

 

[morth]

Correct, 18650 is a size. There are Li-Ion and LiFePO4 batteries in that size. Some RC chargers/conditioners can detect the chemistry, so you may need to get one of those and do a discharge test. Li-Ion is more common, so I would suspect that unless the cells were specifically listed as LiFePO4, I would assume they are Li-Ion.

 

[Rider]

Ok, you've answered the size question.

I guess my big question was, if you get a battery, and lets assume it has no marking whatever, how can you tell a Li-Ion from a LiFePO4, other than the 'full charge' voltage, which could be misleading if the battery was bad. Will a smart charger be able to figure out the difference and tell you? I have one of these on order, but it's supposed to be for Li-Ion only, which sparked this whole thread to begin with!!!

https://gloryder.com/store?olsPage=products%2Fglo-ryder-4-pc-battery-charger

Some RC chargers/conditioners can detect the chemistry, so you may need to get one of those and do a discharge test.

Ok, just re-read and saw this. Thanx.

 

[morth]

Well, you could go medieval on one and heat it up/over charge it. If it catches fire, it's Li-Ion. ;-)

 

[Aussiecroc]

My Soshine 18650 lifepo4 batteries are 1.8 ah. Most lithium ion (not lifepo4) have much higher capacity than that. They are good batteries so far....
They have a lower voltage cut off on the charger (separate setting for lifepo4)

 

[bulrush]

I just thought 18650 implied LiFePO4 chemistry as well as the physical size.

No it does not. The 18650 is for the size/format only. Look carefully for the chemistry of the battery.

AA batteries come in many chemistries: alkaline, zinc, "heavy duty", even lithium (at 3.7vdc) and universal lithium (1.5vdc). 18650s also come in many chemistries like lithium and now LiFePO4.