Test/Review of Efest IMR18650 3100mAh (Purple) 2014

[SIZE=+3]Efest IMR18650 3100mAh (Purple) 2014[/SIZE]



Official specifications:

• Top: flat top
• Bottom: non-protected
• Typical Capacity: 3100mAh
• Min capacity: 3100mAh
• Max discharge current: 10A
• Pulse discharge current: 20A
• Quick charge current: 3000mA (1C)
• Quick discharge current: 2000mA
• Cycle life: 300 times
• Charge cut-off voltage: 4.2V ± 0.5V
• Charge cut-off current: 5A
• Initial Impedance: Max: 15mOhm
• Discharge cut-off voltage: 3.0V
• Temperature: discharge temperature range:-10°C—60°C, charge temperature range: 0°C—40°C
• Storage: 1 year:-20°C—25°C, 3 months:-20°C—45°C, 1 month:-20°C—60°C
• Size: weight: 50g, Length: 65 mm, Diameter: 18mm

High power and high capacity in the Efest purple line of high current cells.










Looking at this curve I will say that 20A is a bit high for continuous load, but 10A is handled very fine.









I had an accident during testing and I am missing one cell in some tests. The problem was that my load did not turn off after the 20A and discharged the cell completely.







[SIZE=+3]Conclusion[/SIZE]

The cell cannot match the ultra high current cells in power, but easily surpass them in energy at 10A. This is very good performance.

I will call it a acceptable cell.



[SIZE=+3]Notes and links[/SIZE]

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 for the review! I have these and the 2500mAh IMR for my higher drain needs! Both work very well.

Who is the maker of these cells? Their bottom side looks quite interesting.

They are made by Panasonic for Tesla Motors. This is the Model S cells for all cars since early 2013 until now, except for the new 90kWh packs.
Thus, it's an extremely high production cell with good safety, durability and low defect rate (around 1 in 100,000,000).
It's graphite anode, Nickel Cobalt Alumimum (NCA) cathode, with some proprietary tweaks that really help safety and durability. They handle overdischarge extremely well, for example.

The bottom is scored and designed to act as a secondary safety vent in the case the safety vent under the positive terminal fails.

Well, that appears to be very interesting tale, but do you have any evidence? By googling I've discovered that these cells look strikingly similar to Panasonic NCR 18650BE, even discharge curves are the same, so even at 10amp, these cells pose serious danger.

Got mine from US dealer. When discharged with 2A down to 2.9V, capacity is 2714mAh, quite far from declared 3100mAh.