Test: Efest IMR 18650 3100mAh 20A V2 (purple)



Top & bottom Label

Discharge Graphs

Charging Graphs


The first photo shows that the wrapper doesn't extend to the end of the battery. This is a modification I made myself to ensure better contact during testing. Please do not do this modification as it may make it dangerous to use in your devices. These batteries are exclusively for testing, but if I were to use it for other purposes, I would rewrap the battery.

The batteries used this these tests have been provided by Covalence of Coval Vapes, a member of Reddit sub /r/electronic_cigarette with no exchange of money to either party.

To simplify testing and prevent mistakes, batteries in each test were charged at 0.5A and discharged to 2.80V.

The discharge tests from 0.2A to 5.0A are done an a Turnigy Reaktor, and discharge tests with higher current are done with a Maynuo M9712C DC external load.

These batteries are rated to 20A discharge. Unfortunately Efest does not say if that is a continuous or pulse rating. Based on the results in the 5A discharge tests, it must be a pulse rating, although I expected better results in the 10A discharge tests than I saw at 5A. I do not think it is suitable for the short pulses of high current used electronic cigarettes either. This graph shows that at 10A, 15A and 20A, the current drops to about 3.6V, 3.4V and 3.1V in approximately two seconds, respectively. I have previously noted that I do not vape, so my assumption may be incorrect. Please analyze the data for yourself and let me know what you think.

Additional battery tests --- How to get more batteries tested.

Thanks for the test. Interesting results. Looks to me like they are poorly balanced compared to other high current battery tests I have read, mostly by HKJ. I wonder how well they would work in parallel or series at higher current draws. Would the difference in discharge curves cause problems?

I think using it in parallel or series might cause problems . I don't know for sure, but I don't want anyone to get hurt, so I'm going to recommend against that.

Great review…definitely NOT 20A continuous…man the voltage dropped out FAST when you pushed them hard

Still 3100mAh at a continuous 5A draw is NOT bad…just don’t push em too hard or they just peter out

Awesome as always HKJ!!!

Either way…I vape on the red Efest 2000’s, these would be a VERY good upgrade as long as they aren’t too expensive

That's a great compliment!

As you said, these can be decent batteries if they're used appropriately.

DOH! Hahaha…getting so people can’t tell you guys tests and reports anymore

Mistake or not on my part (I tend to scan thru quickly and loose mental acuity on who or what is said [and I have a tendency to open mouth before engaging brain {or type}]), …you and HKJ and a handful of other incredible “testers” are heads and shoulders above anyone else in the world…

You guys are most definitely in the leadership caste of the Nerdfighters

I'm sure impressed. And the voltage of the cell stays useable (above 3.4V) for over half the cycle. 5 years ago any 3100 ma cells were just a pipe dream, let alone some you could discharge at high current.

It looks to me that these cells are still substantially inferior to the LGD1 [pink 4.35v] cells. That is some heavy voltage sag coming from a IMR cell, I fail to see the advantage, unless one cannot/refuses-to buy a 4.35v charger.

got a price comparison?

18650 Rechargeable Battery 20A-35A (Free Battery Case) Li-ion 3.7V 3000mAh - Orbtronic :$8.55



the efest are very new, so price is way high…hopefully the price will drop…daggum


I can’t vouch for the high high current use. But I thought the purple Efests were quite well priced in the UK. Certainly cheaper than buying 3100mAh protected Panasonics or similar when I’ve looked about. And I can get them in 1 –2 days.

I’m not familiar with orbtronic, but I’m assuming they are maybe US based? So for me that adds time and significant shipping costs.

Also while I don’t object to another charger, I already have two perfectly good chargers.

As I said, I can’t vouch for the high high output ability of these Efests. I can say that the ones I have do seem to perform very well however in the torches I use them in (Qlite 3.0A driven mostly) and certainly seem to out perform and out last any of my Sanyo or Panasonic ICR’s or other 18650’s I have.

HKJ was disgusted though … jokes people, just jokes. :smiley:

I use them in series in Acebeam K60 (~4-5A in level 5-6) excellent batteries, true capacity and good behavior to this currents (provide energy without warning even at 3,5V, comparing to other Li-Ions which at 3,7V the flashlight start to blink ) .
I don’t know what cell Efest use and how will be the capacity after more charges, but till now are great (not more than 15 cycles).

Goods cells for the money (cheaper than Sony, Samsung, Panasonic)

Efest purchases name brand cells to rewrap. Sometimes the same mah rated cell can be two different brands. You can tell by the number of prongs on top. This cell might be the mh1 but by the 10amp performance not sure. Could be the Panasonic 3100a. Would make more sense on the amount of voltage drop at 10amps