Capacity testing equipment and techniques for higher capacity 21700 cells

[eugenesan]

I have a few questions regarding capacity testing equipment and technique for higher capacity 21700 cells.

I just finished testing 4 cells (Epoch P45B and LG M50LT) and my results are ~10% lower than what mooch posted for both.

In the past, I had no issues testing various cells up to ~2600Mah in capacity with xtar VC4S.
The test was performed at 10C/50F and I guess since all 4 bays of the charger were occupied, the charging was limited to 1A.

Since those are my first 21700 and higher capacity cells I wonder if I need to modify my setup for testing/charging:
* Is my charger not suitable for bigger cells?
* Should I repeat the test discarding the first cycle?
* Should I test 1 cell at the time to minimize thermal/power effects by the neighboring cells?

 

[ShowMeTwice]

The best person to ask is @Mooch. He's the expert.

Mooch tests cells with actual lab equipment not the chargers we commonly use.

One charger will give you different test results versus another charger. And those results - - - In My Opinion - - - are questionable.

Why???

Chargers ≠ Lab Test Equipment.

 

[ShowMeTwice]

The xtar VC4S does support charging 21700 cells. So, yes it is suitable for bigger cells.

Supported batteries:

XTAR VC4S 4 Bay LCD Fast Battery Charger & Capacity Tester

XTAR VC4S is a 4-bay Li-ion & NiMH battery charger. Max 3A fast charging current. It can test batteries' real capacity and internal resistance. Store mode prolongs your battery life.

www.xtar.cc

Per their specs, the VC4S will charge at 3Ax1/2Ax2/1Ax4/0.5Ax4.

I would not consider any of the battery chargers we use to be what I would call proper battery testing equipment.