Test/Review of Efest IMR26650 4200mAh (Purple) 2016

Efest IMR26650 4200mAh (Purple) 2016

Official specifications:

  • Rated capacity: 4200mAh

  • Rated voltage: 3.7V

  • Max continuous discharge current: 40A

  • Pulse discharge current: 60A

  • Lifetime: 500 cycles to 60%

A 26650 cell with current rating.

The discharge curves tracks fairly well and capacity is nearly constant with load.

The battery gets very warm at 30A.


The battery has good performance, but I doubt the 40A rating.

Notes and links

The batteries was supplied by Efest for a review.

How is the test done and how to read the charts
How is a protected LiIon battery constructed
More about button top and flat top batteries
Compare to 18650 and other batteries

Thanks, this looks like a real low IR performer. Interestingly I just tested a purple Efest 4200mAh I got from MTN this March, and the curve looks different. The one I tested has the hump around mid-discharge, similar to the vappower 4200mAh 26650 cell you tested. I guess this is an example of how Efest rewraps cells and you won’t necessarily get the same cell when you buy. Fortunately, from what I’ve seen, they use quality cells.

Again thank you HKJ for these reviews.

This is the newer 2016 Efest battery and it may have been changed or upgraded. In any event a battery test is only relevant to that battery; we assume that other batteries of this production cycle are the same. This assumption would be difficult to verify.