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titleJan 25, 2024 Check-in Meeting

Meeting Notes:

2 new members joined - Shem gave them run-down of team and what we do. One is interested in CAD, and one is interested in Module Testing tasks. I am thinking of giving the enclosure feet validation task to the member who wants to do CAD and have the other member shadow over a module-testing task (if that’s not too troublesome), what do you think?

Enclosure assembly:

  • Enclosure still awaiting from powder coating

Module Update:

  • Vaibhav gave general updates on thermal testing

  • Two modules – 1 (37 degrees celcius) and 2 (32 degrees celcius)

  • Accounting for ambient temperature, it should not be a concern at all

Integration:

  • Jericho finished drawings on .io file

  • Labelling connections between them – Yanshen working with a few people + schematics on how to do that

VDR:

  • Completed, waiting for review from Carmelli

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titleFeb 8, Owen's conversation w/ Tarj and Rohan

  • Cell fuses

  • Teams who get OTS pack use enepaq and orion BMS

  • Fire suppressing material

    • GPO-3

    • Polycarbonate

  • Module Enclosure made from G10

  • TE Sample program

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titleJune 23, 2024 Meeting with Owen about Monitoring for BMS & Other Misc. Things

  • Monitoring over-voltage, under-voltage, imbalance. How to separate conditions that are unideal for cells vs conditions that are genuinely dangerous?

    • over-voltage & under-voltage can lead to thermal runaway, better to leave car in this situation (genuinely dangerous situation)

  • Currently, BMS will fault if cell goes lower than 2.5V. How much wiggle room is there/can we go a little lower than that or is that a hard limit?

    • We’re currently using LGM50 cells, but there is a newer version LGM50T that exists. The datasheet for LGM50T says 2.5V is the minimum guaranteed/recommended good operating voltage, but lower end for safety is 2.0V. Good cell performance cant be guaranteed (might lose capacity) if you go below 2.5V though. Upper end is 4.25V.

  • How large of an imbalance should we allow?

    • Mayy be 0.1V-0.2V (need to confirm)

    • But overall, imbalance itself isn’t an issue. Imbalance is an issue insofar as over-voltage and under-voltage is an issue.

  • What's the max current we can draw?

    • 52A

    • Max expected from motors is 30A, so we'll do check at 40A

  • Safe temperature?

    • 50C for charging, 60C for operating/discharging

    • Shut regen off and solar input after 50C, firmware will need to update for this

  • When should fans kick in?

    • Hard to say, but we’ll ideally want to keep below 50C because of the charging upper limit being 50C

Relevant data sheets in question:
LGM50: https://www.dnkpower.com/wp-content/uploads/2019/02/LG-INR21700-M50-Datasheet.pdf
LGM50T: https://www.batteryspace.com/prod-specs/11514.pdf