Efest IMR18650 3500mAh (Purple) 2017
%202017/DSC_0315.jpg)
Official specifications:
- Rated capacity: 3500mAh
- Nominal voltage: 3.7V
- Voltage at end of discharging: 2.5V
- Max. charging current: 4A
- Standard charge: 2A
- Discharging current 10A
- Pulse discharging current: 20A
- Charging temperature range: 0°C ~ 45°C
- Discharging temperature range: -20°C ~ 75°C
- Inner resistance: 20mOhm
- Cell size: 18.5 (±0.2)mm x 65.2 (±0.2)mm
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-info.png)
A high capacity 18650 battery that can deliver a fair amount of current.
%202017/DSC_0313.jpg)
%202017/DSC_0314.jpg)
%202017/DSC_0316.jpg)
%202017/DSC_0317.jpg)
%202017/DSC_0318.jpg)
%202017/DSC_0319.jpg)
%202017/DSC_0320.jpg)
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-Capacity.png)
The discharge curves shows nice tracking between the two cells. The battery has very low voltage at 20A.
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-Temp-10.0.png)
The battery gets very warm at 10A discharge current.
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-Temp-15.0.png)
At 15A I had to stop the discharge due to temperature.
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-Temp-20.0.png)
I also had to stop at 20A.
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-CapacityTimeHours.png)
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-CapacityTime.png)
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-Energy.png)
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-PowerLoadTime.png)
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-TripCurrent.png)
%202017/Efest%20IMR18650%203500mAh%20(Purple)%202017-Charge.png)
Conclusion
The cell looks very good, it has lot of capacity and can handle some current, but I will not recommend it above 10A.
Notes and links
The batteries was supplied by Efest for 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