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Formula F33 Relay Economizer

Designed, laid out, and routed the relay economizer for the car I'm building with my school's Formula SAE team for the 24-25 year.

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3D view of the board

​The electric power train group on my FSAE team decided to switch which AIR relay we would use on F33, from TE Kilovac EV200  to the TE Kilovac LEV100, due to the current draw being much lower due to a higher pack voltage. The new AIR's were chosen to reduce weight and the overall size of the accumulator front

The EV200’s we’ve been using have a built in coil economizer to limit power draw after the contacts close initially. They advertise 1.7W holding power at 12V. The LEV100 does not, so the inrush and holding power is the same. This is a large increase to 5.5W holding power per relay.

Top layer view

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LEV 100                                                              EV 200
0.84lb                                                                 1.90lb

After discussing with a few more experienced team members i decided to do a pwm based economizer with the clock coming from an ATtiny85. This was only the second board I had made which made it fairly hard for me do find the right components to use and follow industry standard practices as I hadn't spent much time working with them yet. on top of this the form factor requirements were to make it as small as possible which made for a fun and interesting challenge to ensure I had placed everything as efficiently as I could which took a few iterations. Through this project I was able to gain valuable experience working with a layout program and how to efficiently layout a board as well as source cost effective and efficient components.

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The top layer highlighted, including ground pour

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The bottom layer highlighted, including ground pour

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Excluding ground pour

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