Test/Review of Efest IMR18500 1000mAh (Purple) 2016

Efest IMR18500 1000mAh (Purple) 2016







Official specifications:

  • Model: 18500 High Drain

  • 15A Discharge

  • Capacity: 1000mah

  • Material: Li-Mn

  • Flat Top

  • Size:18.39(D)*49.79(L)mm




These batteries are rated for high current and low capacity, but something is wrong. They have fairly high capacity and cannot deliver high current.











The discharge curve looks good, tracking is just about perfect and the cell has nearly double the rated capacity. The cells can handle 7A, but neither 10A or 15A



At 7A the cell heat up, but nothing serious.



At 10A the cell do not have time to heat.















Conclusion

The batteries looks good for high capacity 18500 cells, but they are not high current cells.
Efest must have made a mistake when wrapping these cells.



Notes and links

The batteries was supplied by Efest for review.

As an extra test I did a 1A cycle on my calibrated SkyRC MC3000 and it showed 1906mAh.

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

.

This is Efest how we know them.
For once the other way round.
Thanks for testing, HKJ.

Good to know. Thanks for the test!

Cheers ^:)

P.S.: any chance to get some hint about who is the real manufacturer of those cells?

I do not know it, but with the very good performance I would expect it is from one of the big manufacturers. I.e. you get a top quality cell, but not the type you expected.
It is probably only a limited number of cells that got the wrong wrapper, but if you get some of these cells it would be a good idea to test capacity. If it has high capacity, it is not a high current cell!

I'd better test the battery's ESR, no laboratory equipment here but, if you know what you're doing, even with basic equipment one can achieve wonders.

I have recently ordered one of these 5-digit digital voltmeters; should serve me nice enough to make sort of accurate battery IR estimations.

Cheers ^:)

May be wrong calculation when typing the spec, instead of typing capacity times 2, they do it on discharge current. More likely capacity times 2, discharge divide by 2 :smiley:
Kind of reverse of their previous version which have higher discharge current, lower capacity.
Other than difference between two cells, still looks very good 18500 though.

There is only one cell on the market with this capacity in the 18500 format, that’s the Panasonic NCR18500. That is supposedly a LiNiCoAl cell and the 18500 equivalent to the NCR18650B.

Use HKJs comparator and compare it with the Enerpower 18500 2000mAh, which is known to have the NCR18500 inside. The graph at 0.2A discharge rate is identical. The Enerpower has added protection circuit, so at higher current the curve is lower than the Efest here.

Anyway, I’d never ever buy this Efest. You never know when they will change the cell used in this wrapper and you might get a true but crappy 1000mAh. If I want the 2000mAh, I buy the original Panasonic from a reliable source.

More on 18500s: Runner up is the Sanyo 1700 mAh (LiCo chemistry), then come some worse 1500’s, and then the high drain ones (LiMn, perhaps LiNiMnCo by now) in the 1100-1200mAh range.

Agree. In my honest opinion, these rewrappers which on purpose conceal the true manufacturer's ID numbers on the batteries are shotting themselves in their feet, and potentially harming their customers. It's plain lame. :FACEPALM:

This, for example, is something I can tolerate, no hidden crap here. Shenzen BAK seems to be their manufacturer, hope we can enjoy some kind of test soon (user bella-headlight recently purchased a couple of Liitokala 26650-50A 5000mAh li-ions, same Shenzen BAK cells, we'll see).

Cheers ^:)