Battery Round Trip Test 1

[streetfix]

I am looking for a method or scope of work for battery round trip test for 5kw lithium ion battery using the battery inverter. It's for FAT and I will have to practically show how it can be done. My testing equipment would be 1 x Pylontech battery module US5000
1 x 48VDC power supply
1 x 48VDC load (const current)
1 x DC shunt / Energy Measurement device or calibrated meters
Cabling to suit current selected for constant charge/discharge
TIA

 

[BrianPetersen]

It would help if you explained to the rest of us what you meant by a "round trip test".

For example, in the absence of the definition of what that means, I could book a round trip Air Canada flight to and from someplace warm (Cancun MX for example), take the battery with me in luggage, do nothing whatsoever with it while en route there or back, and if Air Canada successfully returns my luggage at the end of the trip, call it a successful round trip test.

 

[jghrist]

A battery round trip test is a method of measuring the round-trip efficiency of a battery system. Round-trip efficiency is the ratio of the energy charged to the battery to the energy discharged from the battery, and it can represent the total DC-DC or AC-AC efficiency of the battery system, including losses from self-discharge and other electrical losses. The test is used to measure and understand the battery’s round-trip efficiency, which refers to the ratio of energy delivered from the battery during discharge to the energy stored in the battery at the time of charging process2. The test is typically performed using specialized equipment such as a multimeter installation tester, digital clamp meter, load bank, laptop with SP link software, and oscilloscope/scope meter.

See:
K. D. Rao, K. K. Reddy, P. Koushik, B. Avinash and D. L. Madhavi, "Performance Analysis of Lithium-Ion Battery Considering Round Trip Efficiency," 2023 IEEE 2nd International Conference on Industrial Electronics: Developments & Applications (ICIDeA), Imphal, India, 2023, pp. 555-559, doi: 10.1109/ICIDeA59866.2023.10295170.
keywords: {Lithium-ion batteries; Degradation; System performance; Propulsion; Reliability engineering; Mathematical models; Discharges (electric);Round-trip efficiency; Lithium-ion; coulombic efficiency; Ambient temperature; Capacity retention},

 

[streetfix]

Thanks. My equipment are 1 x 5kw battery 1 x 48VDC power supply 1 x 48VDC load (const current) 1 x DC shunt 1 X multimeter. How can I draw a schematic to show this process where i can get voltage values of the battery.

 

[BrianPetersen]

Your first step will be to define the parameters of the testing. At what current? At what "C" on both the charge and discharge sides? With what precision do you wish to have the results? At what battery voltages are you going to consider the battery to be fully charged, or fully discharged? Lithium-ion battery management systems are normally designed to maintain a buffer between the usable voltage range and the battery's absolute maximum and minimum voltages to preclude damage.

Other than defining those parameters ... what's so hard about simply connecting the power supply in series through the current meter to the battery with a voltmeter across the battery terminals, and logging data at suitable intervals (whether manually, at clocked intervals using a stopwatch, or automatically via data-logging equipment), and then when it's done charging, swap out the power supply with the load, and repeat until it's discharged.