Li-Ion 18650 shootout

[jirik_cz]

Looks like they are unprotected...

[gearhounds]

I would imagine they are existing batteries with a makeover. I don't personally have a problem with unprotected but not when they are as expensive as protected cells that already have a proven history/mAh.

[RichS]

Hi Mev - great battery review!

Concerning the low voltage cutoff, AW indicated here (http://www.candlepowerforums.com/vb/showpost.php?p=2961263&postcount=12) that most IC are set to 2.45V cut off in order to make the most of the capacity to work under a reasonable load. The battery will rebound to 3+ V under a 0.5C load. Others have mentioned that in the protection ICs datasheets the level was typically set to 2.3V-2.5V. Your testing seems to validate this, since overdischarge protection did not activate in 7 out of 8 protected batteries due to you stopping the test at 2.71v. So it doesn't seem like the over-discharge is malfunctioning in these batteries, but you just didn't exceed the typical over-discharge threshold.

If that is the case, the only real question is - do most manufacturers including AW set the over-discharge protection too low? What is the optimum safe setting?

I am curious to hear your thoughts on this as this is a very important topic to me as I know it is for many others as well.

Thanks again for your work!! Your reviews are outstanding, and I visit your website constantly.

-Rich

[Mev]

Thanks for the info RichS, that's interesting though/ When I emailed AW, he said that his circuit was designed to cut off at 2.8V and that allowing cell voltage to drop below 2.8V would be bad for the battery. If these cell are indeed now cutting off at 2.45V, it is news to me. Anyway, people I've spoken to personally when discussing li-ion cells all seem to have the same consensus that safe termination should be at 2.8V.

Some related articles regarding safe use of li-ion cells, all state safe discharge is to 2.8V
http://www.gpbatteries.com/html/pdf/Lit ... geable.pdf
http://www.embedded.com/columns/technic ... 176?pgno=2
http://laptoppartsz.com/default.asp?pg=info.asp

From ZebraLight.com

•Battery
◦One 18650 size rechargeable within the 2.8v to 4.5v range, including 3.6v/3.7v Li-ion or 3.0v LiFeP04 chemistries.
◦Reverse polarity protection circuit. Works with batteries that have flat positive terminals.
◦Discharging protection circuit turns off the light when the battery voltage drops below 2.8v.

[Shadow]

My AW cells go below 2.8 . However i usually check them and go no lower than 2.6v .

Also i believe that temperature does effect the limits. Just warming the 18650 in my hand was enough to slightly change the charge level .

[RichS]

Not sure how much it applies to this particular review, but one big factor for incandescent hotwires is the draw allowance on protected batteries. Most every other li-ion I've purchased other than AW's do not allow me to run many of my hotwires with a single click. AW's are one of the only protected cells I am aware of whose protection circuit doesn't kick on at 3.5 amps. It is safe to run a li-ion at 2C, which is ~4+ amps for a 2500mAh cell. But only AW protected cells allow this amount of draw. The other cells have a much lower draw allowance (usually well under 3.0 amps) before the protection kicks in, so you have to use multiple clicks or a soft starter to turn it on. This may be one of the big reasons that AW cells are so popular among the flashaholics/modder community.

[Mev]

Updated with UltraFire 2600mAh pink label.

[phantom]

One word: WOW!!!

[ergotelis]

Really impressive results, just ordered some pink ultrafire!

[phantom]

http://www.kaidomain.com/ProductDetails ... uctId=9519

New cells. Soshine RCR123 has quite decent capacity, maybe their 18650 perform the same