Electronics > Metrology

How to Measure Electochemical Impedance

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trobbins:
I've used the AD630, along with IA's and careful design for lead-acid battery fixed and portable impedance work.  Circa 2005 portable equipment had resolution of 0.5uohm, and a 101 uohm shunt was used as part of the calibration, given use on large lead-acid cells.  Sync demod at a non-mains related frequency was needed to cut through the noise from chargers and all sorts of other industrial equipment for on-line tests on battery strings up to 125Vdc with only low injection current of 0.1Arms for handheld device.  The laboratory basis for SOC versus impedance was done with EG&G PAR 273 and 5208 lock-in amp.

trobbins:

--- Quote from: miro123 on January 29, 2023, 09:48:42 am --- as far as I know EIS meaasuremnts for Lithium baterries is used mainly in three area
  2. Part of SOH & SOC estimators in high end BMS - eg EV BMS

--- End quote ---
I wouldn't think that was at the cell level within a bulk HV dc string in EV, although I've only quickly looked at Tesla battery tear downs.  For fixed applications based on rack mounted modules, the embedded BMS in circa 20-60Vdc modules I've come across were only cell voltage and temp based, but that was a few years ago.

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