Test/Review of Eizfan IMR26650 3500mAh (Gold)

Batteries and Chargers Rechargeable Batteries
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Eizfan IMR26650 3500mAh (Gold)


Official specifications:

  • Model No.: IMR 26650
  • Rated capacity: 3500mAh
  • Nominal voltage: 3.7V
  • Size: Diameter 26.13, height 65.56mm
  • Weight: 95g
  • Resistance: 23±2 mOhm
  • Temperature range: -20~+60 ºC
  • Monthly Self-discharge rate: < 0.5%
  • Temperature range: Discharge: -20~+60 ºC, Charge: 0~45 ºC
  • Maximum discharging current: 35A
  • Maximum charging current: 6.5A
  • Maximum pulse discharging current: 65A




A high current 26650 battery according to specifications, as can be seen below that is not correct.











When the test was finished and I removed the battery from my test station the plastic wrapper was damaged due to heat, as was my test station.
This means that the curves for the second battery may be a little bit off, due to the damaged test station as was my next few battery test, until I discovered the damage and fixed it and has started a retest of the affected batteries.



Some of the differene at high current is probably due to the damaged test station, but the capacity difference in the 0.2A track cannot be from that.
The curves looks like the battery can deliver 30A, but obvious it gets to hot doing it.















Conclusion

The batteries has some capacity difference, this means that they must not be used in series and I would stay well below 30A when using them.



Notes and links

The batteries was supplied by Efan 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

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Wow, the battery became hot enough to melt the wrapper and damage your test station? :open_mouth:

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Yes.

I use this type of clamp to hold the batteries:

Some of the yellow plastic melted, making the connection a bit unstable, but not enough to make it obvious when I replaced batteries. The copper rods do transfer heat rather well.

It is, of course, easy enough to fix, I just need to tighten the copper rods.