Before diving in to manufacturing the modules, we need to have a solid understanding of how our modules heat up, how much cooling we need, and where that cooling will come from.
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| Equipment | Manufacturer | Model | Acquired Where | Purpose | Notes |
|---|---|---|---|---|---|
| 2.5kW DC Load | HC Power Inc | HCL-2501-1 | Pegasus Aeronautics | Draw power from our modules to make them heat up | Micah Black (MSXIV battery lead) had a co-op at Pegasus and was able to borrow this. (white wire GND, yellow wire +, 10mV/A for the reference voltage). 1.25-80V, 500A, 2.5kW (https://www.valuetronics.com/product/hcl-2501-1-hc-power-dc-electronic-load-used) |
| Power Supply | BK Precision | 9103 | Bay | Charge the module (20A) | Use 3 banana-alligator cables for the full 20A |
| Power Supply | Keysight | N8740A | Bay | Charge the module (10A) | Diode in power line heats up too much for comfort at >10A |
| Power Supply | Agilent | E3616A | Bay | Provide reference voltage to set the DC Load | |
| Power Supply | Agilent | E3631A | Bay | Power the fans and DAQ | |
| 64-channel 16-bit DAQ | Custom | Custom | Bay | Measure the thermistors! | This was custom built to measure the thermistors. Ask Micah Black if you want more details on it. |
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From these graphs, it looks like we will need either more airflow, a more directed airflow, or a channel to get more air through the middle of the module.
Tests to come will include data on what we were actually trying to determine - cooling the module with a carbon fiber plate. We might play around with some airflow guides Cooling the module with a carbon fiber plate proved to be ineffective. The carbon fiber did not raise in temperature at all. This was verified by attaching a heater to the carbon fiber plate, and observing where the carbon fiber heated up. We measured the temperatures of the carbon fiber plate and concluded that the thermal conductivity through the plane (through the layers of carbon, foam core, carbon) was much greater than across the plane. The temperature on the opposite side of the plate, underneath the heater was fairly hot (almost at the temperature of the heater) and the temperature of the end of the carbon plate on the same side as the heater did not noticeably rise in temp above ambient.
A few articles on the thermal characteristics of carbon fiber epoxy are linked below:
https://www.christinedemerchant.com/carbon_characteristics_heat_conductivity.html
We will experiment with some airflow guides to direct the air through the module instead of around it as well.