Power Assembly

This page contains the report of the assembly of different parts of the power subsystem as performed in the cleanroom.

Bottom Shell Assembly

Umbilical Connector

Footswitch Assembly

EPS-CTRL Board Harnessing

Saddle Assembly

Installing the RBF bracket

Harnessing the Batteries

Solar Panels Assembly

Top Shell Assembly

Bottom Shell Assembly

Umbilical Connector

The first thing installed on the bottom shell is the umbilical connector as shown in the Picture below on September 29, 2022

Umbilical connector secured on the shell with the wire shielding connected to the structure.

On October 6, 2022, the assembly was continued by securing the umbilical harnessing to the shell using lacing cords.

Umbilical harnessing restrained using lacing cord

Closeup view

Footswitch Assembly

On September 29, 2022, the harnessing for footswitches was soldered and the footswitches were assembled on their brackets.

Harnessing soldered on the footswitches

Footswitches assembled on the brackets

Footswitches ready to be assembled on the battery saddle

The video below shows the performance of the footswitches and cutting the circuit in cases that each one is pressed. This is the final version of the bottom footswitches tested on October 19, 2022. The second pin being pressed (top left in the video) does not correspond to any switches and that's why it has no effect on the multimeter's reading.

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Pictures below show the assembled bottom shell with all the harnessing in place.

Harnessing for the heaters, thermistors, RBF switch, and Footswitches are completely routed and restrained using lacing cord.

Wide view of the harnessing

Battery harnessing routed and restrained with lacing cord

Close up view of the battery harnessing

Picture showing the lacing cord tied on the outside of the bottom power shell (right view)

Picture showing the lacing cord tied on the outside of the bottom power shell (left view)

The harnessing was tested for continuity to ensure that the connections are proper as shown in Pictures below.

RBF removed: no connection between the pins

RBF inserted: short circuit between the pins

Footswitches are depressed: no connection (before deployment)

Footswitches are released: short circuit (after deployment)

Saddle thermistor #1: reading 10.23 kilo Ohms

Saddle thermistor #2: reading 10.27 kilo Ohms

DATEC heater resistance: 5.65 Ohms as expected per heater's specifications

MICNO heater and thermostat connection: no connection due to thermostat being open

Battery voltage of the lower 3 cells = 3.2069 V (fully discharged)

Battery voltage of the upper 3 cells = 3.2000 V (fully discharged)

EPS-CTRL Board Harnessing

The wires were soldered to the EPS-CTRL board on October 21, 2022, as shown in Images below.

Saddle thermistor shields connected to the ground reference and insulated with Kapton tape before soldering to the board.

Covering the bottom shell before soldering to keep contamination out of the assembly during soldering

Soldered wires of the battery saddle thermistors

Soldered wires for footswitches and RBF switch and CAN bus. Connections are covered with Kapton tape to avoid accidental bridging

Soldered long wires to the solar panel thermistor inputs

Exposed connections are covered with Kapton tape to avoid accidental shorts

Saddle Assembly

On August 22, 2022, we started the assembly of the battery saddle. Below are some pictures of the procedure including the assembly of the DATEC heater using thermal epoxy, Assembly of the MINCO heater and the Thermostat, and the bottom cells on the saddle.

Testing the DATEC heater before integration. The expected voltage and current are showing on the power supply.

Measuring 50g of Stycast 2850 for epoxy mixture

Adding 1.8g of catalyst 9 to achieve 100:3.5 mixing ratio

Applying epoxy mix on the clean surface of the saddle where the DATEC heater sits

Covering the Entire surface area with epoxy

Evening out the surface using a squeegee

The fully covered surface before installation of the DATEC heater

Placing the DATEC heater and the Kapton tape cover on the epoxied surface

Securing the DATEC heater using the PCU plate and fasteners and nuts to the saddle until the epoxy cures

Preparing the thermostat by applying thermal epoxy on its contact surface with the battery saddle

Securing the thermostat using nuts and fasteners

Top view of the thermostat after assembly

Installing the MINCO heater on the saddle using its own thermally conductive adhesive patch

Clamping the sides of the saddle to ensure even force distribution while the epoxy cures and preparing the battery holder for installation of the cell

Installing one cell on the bottom side of the saddle and preparing the other holder.

Finished view of the bottom side of the saddle assembly

After the bottom side of the saddle was assembled, we had to wait at least 24 hours for the epoxy to cure. The next day, on August 24, 2022, we continued the assembly as shown in Images below.

Bottom side of the saddle after the epoxy was cured

Bottom side after removing the clamps. Ready to continue the assembly on the top side

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This video shows the functionality testing of the DATEC heater and one saddle thermistor. We can observe the resistance decreasing which indicates increase in temperature.

Temporarily installing one thermistor and measuring its resistance to ensure its functionality. DATEC heater is powered and 10.54 kilo Ohms is showing.

After letting the DATEC heater run for a while, the resistance drops to 9.44 kilo Ohms indicating an increase in temperature.

Epoxying the first thermistor to the saddle and securing it with Kapton tape

Adding additional epoxy around the MINCO heater and securing its harnessing using Kapton tape

Installing the second thermistor on the battery saddle.

Installing the upper cells on the top of the saddle and ensuring they are centered.

Top view of finished assembly

Finished assembly of the battery saddle.

The assembled saddle above needed at least 24 hours for the epoxy to cure. Post assembly inspection was conducted on August 25, 2022. Images below are showing the assembled saddle after the epoxy was cured.

Top view

Bottom view

Side view

Installing the RBF bracket

On September 16, 2022, the RBF bracket was assembled. First the harnessing was soldered to the switch and then the switch was installed on the bracket.

RBF switch assembled on the RBF bracket

RBF pin inserted

Harnessing the Batteries

The batteries were soldered together to form two separate 3P packs. This part of the assembly was done on October 5, 2022. The exposed contacts were all covered with Kapton tape to avoid accidental shorts during assembly and launch of the satellite.

Soldering jumper wires to the solder tabs

Covering the exposed areas with Kapton tape

Closeup view

Soldering the tabs of the top cells to the bottom cell using a jumper wire

Covering all the exposed wires and battery terminals

Bottom view of the assembled battery pack

Top view of the assembled battery pack

Solar Panels Assembly

On August 5, 2022, we started the assembly of the solar panels. This assembly consists of mixing conductive silver epoxy and applying it on the surface of the solar panel PCBs and carefully mounting the cells on the appropriate surface. Lastly, the epoxy needs to cure in an oven at 120 Celsius for one hour. Images below are describing the procedure.

The solar panel PCBs were previously masked off and cleaned. The exposed surfaces will be covered with silver epoxy to provide current path for the solar cells.

4.5g of Part A of the silver epoxy was measured. Mixing ratio of Part A and Part B is 1:1

4.5g of Part B also was measured. The epoxy is mixed in a small container.

To ensure adequate amount of epoxy mixture is distributed on all surfaces, each surface will have 0.9g of the mixture

Using squeegees, the mixture is evenly applied on the surface of the PCBs. The thickness of the epoxy will be approximately 0.2 mm

Three of the stationary panels after being covered.

Applying epoxy on the deployable panels.

Evening out the epoxy using a squeegee

A panel after removing the masking, ready to install the solar cells

Cleaning up any excess epoxy before installation of the cells

More cleanups! (Ft. Mitesh (Left) and Aref (right)!!)

Attention to details! (Credit: Mitesh)

Panels before installing the cells

Panels after installing the cells

Panels in the oven before curing. The panels were transferred to another cleanroom to access the oven.

Panels in the oven after curing for 1 hour in 120 Celsius

Final view of the panels.

The solar panels were then transferred back to the main cleanroom (ASIF) and were stored in our repository. On August 19, 2022, the final step of the assembly was done which is soldering the solar cell tabs and panel thermistors.