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titleMeeting Minutes 2023/09/05

Vehicle range sensitivities

Super rough range sensitivities I came up with. These represent the expected range loss per day due to an increase in one of these factors:

+ 1kg:

  • - 0.5km/day

+ 1W non-drive:

  • - 0.7km/day

+ 0.001 Cd:

  • - 2.3km/dayTLDR: We should prioritize aero when considering trade offs

Aero Status

Areo ideal: 0.09 Cd

Aero current: 0.20+

  • Skin friction drag largest source of non-ideality, followed by panel gaps

    • Lots of sanding work required to get that down, panel gaps can be taped up

  • Sim also missing wheel wells

    • Maybe possible to cover bottom opening with cover attached to upright

  • Path down to 0.13

Battery box wiring / ports

Connector options:

  1. 2 external HV connectors (motor/dcdc) + 1 LV 4 pin

  2. 1 external HV connector (splitter outside BB) + 1 LV 4 pin

  3. 1 external HV (dcdc inside battery box) + 1 LV 8 pin (for DCDC out, BMS pwr from PD, CAN)

    1. Preferred to reduce umber of HV connectors (and simpler HV wiring vs option 2)

Boards Inside BB:

  • BMS Carrier

    • AFE 1

      • AFE 2

        • AFE 3

    • Current sense

AFE Temp Sense

  • 16 thermistors - 2 for board and 12 for 3x modules, 2 NC

BMS FW

Cell balancing

  • Goal is to make sure the pack charges fully

    • Cells charged in series charge at slightly different rates due to manufacturing tolerances

    • Series must stop charging when first cell reaches full, even if other cells are not yet full

    • Cell balancing will discharge cells that are “too full” so remainder cells can charge fully and bring the whole pack up to max capacity

BMS Fans

  • How to achieve fault detection without fan controller?

    • Monitor current through shunt

    • Read fan tach from CB

Lights

  • Probably don’t need multiple wrap around lights since they only need to be as bright as reference, and there will only be 1 reference light

  • Ref DRL discontinued, but replacement has similar specs, to confirm with asc if they are okay.

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titleMeeting Minutes 2023/08/02

PD validation update + lessons learned @jenna k

  • Power rails were up at first, encounter smoke

  • Observed current spike on display of pwr supply, board started smoking

    • Intermittent issue, happened 3rd time immediatly but not first 2

    • Zener diode was shorted between pwr/gnd

    • Something else was smoking but it still works

  • 3v3 from CB was at 1.8V

    • 12V*0.042A = 0.5W

    • Replaced CB connector which fixed the issue

  • 5v outputs 5v5, should be 5v2 based on FB

  • In the future to set low current limit when powering boards

Update from ASC @Jonathan Xie

  • Basically okay, small brained some things but we good?

  • Stated only issue was can’t power steering and drive

LV Power Distribution

  • Quiescent draw of AFEs from main pack

Current sense architecture @Soumav Maiti @Mitchell Ostler

  • Pass relay power through for cutoff

MCI/transition to drive state @Forest Zhou @Mitchell Ostler

Press button to drive, what happens?

  • Enable HSD to MCI

  • MCI triggers precharge start

  • Precharge closes motor contactor once complete

  • MCI reads precharge complete

  • Drive mode indicator comes on in CC

...

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titleMeeting Minutes 2023/07/12

Participants:

Lights

  • Strongly consider use reference lights if they can solve for brightless while being within aerobody

  • Decision on custom vs ref lights pending response from regs

BMS

Questions

  • do we pull over

    • What do we do to swap

  • Are all the things we have BPS since they control BPS

  • Justify why all the components are required for safe startup

AUX

  • To ask if we can keep driving if aux dies

    • Assuming relay is redundantly powered, are any of the other loads drive critical

    • We think not, we can keep driving if aux dies pending regs

  • UVcutoff isn’t pwoered on startup, add output to a load switch on PD

    • Otherwise you cycle if aux batt is dead

  • CC should be on during startup since its the central fw element

    • Also in case of BMS fault during statup we want to have indicator on CC

  • Ask regis if we can power PS CC PD UVC + other things (what is included in BMS)

  • Aux batt needs to go in a battery enclosures

    • Ask about process of swapping aux

Power Up Logic

  • Fill in later

Active SCP

  • In firmware from current sense to carrier ~10-15ms

...