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theoretically 16% outliers on either side of the normal distribution for cells for testing (normal distribution characteristics)
have to check the cells within 6 months to make sure none of the outliers are deficient
put the outliers in a separate isolated container
Some people will just get rid of reflow ovens - keep track of industry
Dan was a battery guy at Missouri
Won with lead acid batteries in the age of NiMH and NiCd
Push for 1000 miles of testing!!!
GM EV1
Steve designed the motor and gear train and battery
All cars were destroyed - protect liability
Michigan has both Ford and GM as sponsorships
Sponsor with the engineers
‘Tesla can’t get along without active balancing or sorting'
Getting air through the cells
Airstream such that the cross secitonal area grows as it travels along
Distributed airflow via perfboard (distribution method)
Maintain flow in the battery pack
You know the heat in the cells - that will dictate the amount of air through the cells.
How much heat can you get into the air?
Conical washers - make sure to use them
Not enough length of bolt to cause stretch in the bolt
Busbar heats up and cools down - relaxes the pressure over time
Post-assembly thermal test on the connection methods
IR camera, etc.
Steve is a bit worried about the stainless for the material flow
Need to have SoC (voltage) for each of the supplemental
can have self powered sensor if it is not driving the car in any way
Don’t want 40 sensors and no supplemental
WSC does not allow any supplementals
Teams that have tried to modify Tritiums have caused Tritium problems…
Western Michigan has used Tritiums for quite some time
Lengths can be pretty estimated for wiring diagram because small changes can happen on the fly
maybe have an extra foot of wire
label wire on either ends of the interconnects
Abrasion failures - suspension-caused
motor sense leads
Power leads
Pigtails and such to the array - pulling contact sense off the arrays
ALWAYS RESTRAIN WIRES - EVERY PIECE
Holds up in weather and heat
addition to wiring diagram
Feb 25
Question 1: What are the areas of innovation in battery technology?
Energy capacity is going up
Anyone that does balancing is wasting energy …?
Weaker cell limits the pack
Question 2: How do people enter this field
industry is going leaps and bounds
???
Question 3: What kind of skills needed to be better with battery technology?
Have to understand characterization of batteries
So a bunch of chemical knowledge of cells and their energy capacity and how that affects electricity
BatteryUniversity - website for learning stuff about batteries
compendium for battery knowledge
Question 4: In your experience doing inspections, common problems seen with solar cars?
Checks regulations to use
Teams usually forget:
Power labels on switch and driver compartment
Labels on emergency switch
More extreme problems:
Teams don’t have an isolated car
Dynamic braking