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My cell testing equipment and setup

Published by Mooch in the blog Mooch's blog. Views: 5708

This is the equipment I use for cell testing:

  • West Mountain Radio CBA IV Pro battery analyzer, modified for low voltage drop . Accuracy = +/-1% up to 20A.
  • Custom constant-current electronic load, rated 150A/400W. Accuracy = +/-0.6% up to 150A. A second load is available, if not being used for other testing, if I need to discharge at over 150A (up to 300A).
  • Adjustable 5A/30V CC/CV power supply for charging the cell.
  • Omegaette HH308 dual type-K thermocouple thermometer. Accuracy = +/-0.3% + 1C.
  • 20A, 100A, and 200A current measuring shunts. Accuracy = +/-0.25%.
  • Fluke 8846A 6-1/2 digit DMM. Accuracy better than +/-0.01%.
  • Low-resistance cell clamping rig.
  • Safety glasses, fire-resistant apron, fire-resistant gloves. I wear all when doing destructive testing or if I think the cell temperature will rise much above 100°C. Otherwise just the safety glasses.

  • The CBA battery analyzer handles 10% of the discharge current and creates the graphs. The custom load handles 90% of the current.
  • The cell has its wrapper removed so the thermocouple can be placed directly against the metal can to sense temperature.
  • The thermocouple, plus 0.5" of its cable (to prevent ambient air from cooling it and affecting the thermocouple), are tightly Kapton-taped to the cell with the thermocouple positioned halfway down the cell.
  • All discharges, unless noted, are constant-current to within +/-1% of the stated value. Confirmed via +/-0.25% tolerance current shunt.
  • All measured temperatures were rounded to the nearest degree-C. Only the highest temperature for the discharge is recorded.
  • The cell is placed in an insulated fireproof container with a lid loosely placed on top. The container is left open at the top to allow heat to escape during discharge. If a cell vents the cover is closed and a fan is turned on to evacuate the gas/vapor outside via a flexible metal hose.
  • The cell holder is a non-conductive c-clamp using a 1" x 1", 0.040" thick copper plate to connect to the bottom of the cell. A 1/4" diameter copper rod is used to connect to the top of the cell. Both the top and bottom connections have 10AWG and 12AWG silicone-insulated wires soldered to them. The 10AWG wires go to the 400W load and the 12AWG wires go to the CBA, directly soldered to the CBA circuit board. I do not use the CBA's PowerPole connectors as their resistance is too high.
  • Why only a 1/4" copper rod for the top of the cell? One reason is that's the equivalent of 3AWG wire...plenty beefy enough. The other reason is that I don't want to conduct any more heat from the cell than I have to.
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