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- How do you select cells?
- how do you design a protective shell?
- mounting options ingrained in the case?
- heat sensing?
- heat dissipation? how important to design for this?
- How to effectively calculate power requirements of a complex system?
- At which stage in the design cycle is the battery designed? (before/after motor selection, before/after full electrical system diagram)
- How to deal with/account for in-rush current?
- testing vs calculation
- battery placement within the system? - is this important?
- sourcing? CELL VENDORS THEMSELVES
- Active vs Passive balancing?
- Copper wiring/Soldering
- Connectors
- Assembling the battery - how important to test each cell and specify each cells location based on resistance?
- Spot welding - worth it to make a pcb supercap thing for that?
- bms on the battery? or separated?
- hexagonal or square grid pattern?
- vertical stacking? - some one else advised against this, but it might be nice to have a flatter battery NO DONT DO THIS
- how to charge, with bms or without?
- What to expect during assembly?
- expected costs? cost savings?
- Other cell chemistries to consider?
- Diagnostic tests to run?
- Critical data query functions?
- Hierarchy of protections?
- Firmware Architecture? Use OOP to send commands to BMS and store data?
- Is it useful to manually trigger the FETs or allow BMS to handle it?
- Ideal calibration procedures?
- Optimal to use IC as a peripheral and have microcontroller sample it for necessary data?
- When to use FUSE functionality?
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Notes at meeting:
- big motors need to be at Vbat,
- Data, Calculations: peak power, total power
- higher discharge, lower life
- 50E, 30H - power drill batters - life around 50A
model system as good as posible to see the loads
power train loads will dominiate
- biggest incline, target speed, - gearboxes → efficiency
- can translate speed up a hill to power requirement
- get current requirements
get battery current requirements
NEED TO CONSIDER POWER REQUIREMENT AT LOWER STATE OF CHARGE
power draw relartive to battery size → look into heat dissapation
size away the problem by making battery bigger → make issue go away eg lower C rating
Battery Sourcing
- Tattu still our best bet unless we get something direct from cell vendor(???)
- 22000mAh, 22.2V at 2.7 kg, $212 Aliexpress Tattu
- 30000mAh, 22.2V at 3.7kg, $405 Aliexpress Tattu
Ampacity or Energy
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IC Specific(may not be useful)
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