[DRAFT]
Objective:
To choose a module prototype to move forward with. [NOT PRODUCTION LEVEL TESTING]
Thermal Performance: Is the module easy to cool? Are there risks of a thermal runaway?
Electrical Performance: Does the module work? Are there areas with extremely high current density? IR?
Context:
put our packs/modules/cells through <100 cycles
“The major effects (sudden capacity loss) are most likely to appear after 100 cycles of the pack, however, minor effects will always be present” [2]
our pack will be assembled for 1-2 months
Background Information:
OEM Specs:
It is important to inform our test procedure from the OEM specs for the cells we are planning to use:
Metrics:
Capacity
“A capacity drop in any one of our modules will affect the whole pack” [2]
Thermal Performance
The module will be subjected to varying cycling patterns in various environmental condiyions. It should be easy to cool and safe from thermal runaway, melting, shorts, etc.
Procedure:
Software Setup (Skip)
Install (follow their respective instructions closely)
2. Set up development requirement
Create a python venv or anaconda environment
Install libraries according to requirements.txt
Hardware Setup (Verify)
Plug in Keysight N7000 series power supply
Wire the A2D 64 channel PCB into the Keysight DAQ970A
Plug the power supply into the B&K Precision 8600 E-load
Connect your PC to the DAQ and E-load
Test Setup
Close wind-tunnel
Power on PowerSupply, DAQ, and E-Load
Testing
navigate to /battery_testing/Test_Equipment_Control and run the following command in the terminal
python battery_test.py
2. Enter 1 Battery Channel
3. GUI:
4. Click assign equipment
do you want to connect a power supply for channel 0: no
do you want to connect an eload for channel 0: yes
do you want to use a separate device to measure voltage on channel 0: no
do you want to use a separate device to measure current on channel 0: no
do you want to use any other dmms: no
do you want to add a relay board for channel 0: no
5. Click Configure Test
name the test: msxv_prototype_test (can import test going forward)
select
3. select the following settings:
16.8V: 4.2V * 4, end-voltage
11.6A: 1.45A/cell*8, current
0.4A: end-current
15 Minutes: rest
10V: 2.5Vx4, end voltage
12A: 8x1.5A, discharge current
20 Minutes: rest
1s: measurement interval
4. do you want to save these values for future use: no
5. do you want to do a storage charge: yes
6. would you like to import new settings for charge only cycle
7. Click start test
We will charge and discharge each module, assuming that the modules have the same capacity and are at the same voltage.
During the entire test, log the voltage, current, and temperature for each cell. Multimeters to log single cell voltages (XXs interval (fast as possible)), and DAQ module to measure the thermistors (5s interval).
Storage Charge
Storage Charge + Inspection
Storage Charge to maintain cell safety
33.6V max voltage (~4.2V/cell)
5.8A CC portion
25A end Current
We don’t want the storage to take a ton of time - we don’t need to wait for the current to drop all the way - voltage will sag a bit after finishing the charge, but we have increased the voltage to 3.8V/cell instead of the standard 3.7V/cell to account for this.
After the above procedure is followed, we will calculate the capacity of each of the parallel groups to ensure there are no major discrepancies. Any voltage limits that were exceeded or not hit correctly, we will be able to create a model of the LG M50 cells and use that to extrapolate the data to get a full-capacity measurement. We will also examine the temperature graphs and the IC/DV graphs to ensure the uniformity of the cells.
References:
[1] The Fundamentals of Battery/Module Pack Test (nhresearch.com)