Test/Review of Efest IMR18650 2600mAh (Purple) 2016

Batteries and Chargers Rechargeable Batteries
1

Efest IMR18650 2600mAh (Purple) 2016



Official specifications:

  • Rated capacity: 2600mAh
  • Nominal voltage: 3.6V
  • Voltage at end of discharging: 2.0V
  • Max. charging current: 4A
  • Standard charging current: 2A
  • Max. continuous discharge current: 30A
  • Pulse discharge current: 40A-60A
  • Charging temperature range: 0°C ~ 45°C
  • Discharging temperature range: -20°C ~ 75°C
  • Internal resistance: 8mOhm
  • Cell size: 18.30mm x 65.80mm













Very nice curve, the batteries match perfectly and the capacity is fairly stable up to 20A.
These curves are made with my new 4 terminal rig, this means the voltage at high current discharge will be higher than in the old test. I do also expect better matching between curves at high current (With good cells), because connection resistance is not included anymore.



How hot do the cells get during discharge? I have added a termo sensor to my test stations and will show temperature traces for high current discharges.
They will only show the temperature raise, not the absolute temperature, the actual cell temperature is 25° to 30°C higher. If the cell gets too hot I will stop the discharge to avoid melting my battery holder.
The temperature sensor will always be a bit behind the real battery temperature.





Here the cell gets to hot a few seconds before it is empty and I terminate the test (It is automatic).















Conclusion

The battery has very good performance, but it gets very hot at 30A.



Notes and links

The batteries was supplied by Efest for a review.

Improvements to test stations
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

2

Great to see you upgraded to a 4-terminal rig - it was about time :slight_smile:
Makes your results even more valuable, stable, reliable, comparable.

And even better: you added temperature measurement. Wow.

Do you plan to compensate for contact resistance in old data from the 2-terminal rig so that it’s better comparable in the comparator? I see it’s not so easy because you’d have to assume some resistance, e.g. 10mOhm, and apply this to all measurements, at least to the discharge curves for the comparator.

As for the tested batteries: they look excellent, unprecedented matching (good part of this attributed to the new rig).

3

I wonder what these are, underneath the purple wrap. Thanks, as always, for the review.

4

VTC5? Quite sure…

5

No, I do not like faking data. Instead I mark the new tests with *

But do not expect everything I publish from now is with the new rig, I have many tests from the old rigs that is not published yet.

6

I also think they're VTC5, see http://lygte-info.dk/review/batteries2012/Common18650comparator.php