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CHADEMO based battery testing

Posted: Wed Nov 22, 2017 7:58 am
by WetEV
I'm wondering how much market there would be for a CHADEMO based battery testing service.

Thermal soak the car to a known temperature, charge the car to 100%, plug in the tester to the CHADEMO, controlled and measured discharge to a low charge percentage, verify cell voltage balance, and print a nice report.

It seems like this might be valued by a car buyer or seller as the condition of the battery is both important and how to know.

The thermal soak would be required to get a consistent test. Batteries hold more energy at higher temperatures. So put the car into a garage with a big fan moving air over the battery. Could just be controlled temperature air for long enough. Charge to 100% with L2 sometime late in the temperature soak. This process might take a couple of days.

The tester would set up a V2G session at a moderate rate, say 0.4 C, and discharge from 100% to 20% (or something like that). Circuit would include a calibrated voltage and current logger. Probably best to use a measured voltage to set the end of discharge, rather than the car's reported SOC. This process would take a couple of hours. Perhaps something like this:
With a pass through CHADEMO cable with voltage and current monitoring.

The report is "just software" and I can see an ex-boss chucking while I write that, but would be key to the customer.

Re: CHADEMO based battery testing

Posted: Tue Apr 24, 2018 1:28 pm
by Marktm
Would you expect the results to be significantly more accurate than the Leafspy results of amphours/GIDS/voltage readouts and extrapolating to the full energy from 100% to 0% charge? An interesting load test idea! Not sure anyone has an accurate SOC curve for the particular cells in a specific year Leaf? I'd like to see for my "Lizard" battery - the full 100 to 0% with various "C" and temperature curves.

Another question - does the new 2018 Leaf support bidirectional energy via the CHAdeMO port? Has anyone designed such a bidirectional energy converter using 240 VAC split phase in/out? Princeton Power makes a commercial unit - don't know anyone that has actually used it. If I'm not mistaken, the PP can also work with 480 VAC 3 phase.

Re: CHADEMO based battery testing

Posted: Tue Apr 24, 2018 2:22 pm
by SageBrush
Most dealers and buyers set the car price by the odometer, year of manufacture, cosmetic condition, and "capacity bars."
They would have no clue what you are talking about.