Dale Reid / BPS, electrical, MOV charging

If you organize a 1-on-1 with this person, then fill in the timeslot and your name in the table below.

He’s doing a part-time PHD: http://ampere.engr.uky.edu/people

Question 1: Is the situation in which a team tests the limits for there BPS system before hand, arrive at the site for scrutineering, then find themselves failing the BPS checks one that arises often? If so, can you think of any factors of the environment or situation that may cause that?

• Teams will build custom circuitry - digital circuit

  • Microcontroller will shut down

    • flip a switch, power on a large load, get a large bus transient

    • Sucked all the energy out of the caps

      • holdup diodes to keep micro powered

    • DC-DC converters spread all over the car - thermal shutoff

• When they were racing (2008) - Kentucky team - 2300mile, Austin to Calgary

  • 120V-5V Vicor module, and a couple spares available

  • Had some low modules - used the vicors

    • Use the pack to charge the pack - even if it its manual

  • Notoriously had trouble with terminal breaking - pouch cells and road vibrations, etc.

    • Such low budget and resource-constrained

Question 2: When can we expect to have access to a charging meter before a race? (Receiving a meter before a race was briefly in exchange for a deposit was discussed in one of the meetings.)

• Stay tuned…

• Evan is building them. He has some already

  • Evan works really hard

• Pilot and control signal must be wired separately

  • J1772 extension cords would have been a different solution

  • Let Dale know about the grounding of the metal chassis

  • IT industry (PCs, printers, etc.) use a real high standard of insulating - anywhere you can touch “doubly-insulated” or “reinforced isolation

    • Chargers are not built to that same standard - is NOT build for double insulation - chassis and AC power - chassis could become energized.

    • Build circuits to sell on the market - ALWAYS connect the chassis to GND.

    • Generator is not earthed

      • Instruction manuals likely state that

      • GFI protected outlets - How does it know?

        • Monitors current in both terminals

        • “Earth” is floating

        • Monitors current in both hot and neutral and a difference in them will trigger if

        • Prevent AC power from getting out into the chassis

Question 3: Your own projects on the solar team

“I was the electrical team”
”I was real stubborn”, just liked to build things - that’s just how its going to be. Not going to buy them, just going to build it.

MPPT trackers

• “Textbook boost converter circuit”

  • Never successfully made it through a race. Somebody else’s subsystem would always apart.

2008 car

• Just dreamed up a BMS and tested it, several iterations

• Didn’t use any LTC chips, etc.

• Used it 2008 until 2018

  • Some boards were still the original

• A fan of capacitor circuits

• Optical isolated FETs

• Used a 1uF capacitor, 1 per module.

• Across the capacitor was a set of FETs - 4 of them

• Capacitor would charge to the battery voltage, then would get isolated from the pack

• Opamp buffer circuit

• Analog switches, piped into a microcontroller ADC

Berkeley team - the guy at Berkeley has done an incredible job - best power point tracking system

• Has published some papers on it

• Flying capacitor boost converter MPPT - google it.

• Frequency multiplication effect - so inductor, etc. can be absolutely miniaturized - 1/4th of the size and 1/10th weight of anything you can buy

• Crazy high boost ratio capability - all the way down to 3V - he might make it commercial someday

• Might be this one: https://ecal.berkeley.edu/files/EECS498.pdf

Question 4: Do you often see teams failing insulation?

Not really - just run a

Question 5: Solar array to chassis?

“Our array is producing nothing” - “Oh look its shorted out”

• Always check this

Question 6: Excel is awesome

VBA built in to it.

• Factory had PLCs built in but needed a database system and number-crunching tabular data

• Made ~50 different widgets

• Controlled their whole assembly line through EXCEL and Access

• Tables of data. Line would communicate with the system

• Bins of parts that you needed to use would light up with LEDs.

Battery charge/discharge with python

• Communicate with the SCPI built in. Program will pull data and throw it into Excel

• Make it using a table - will grow dynamically - then chart data from a table

• Dynamically charting the data.

• Setup a timing loop - every second will go a pull the data - GPIB communication

• If statements - for start/stop criteria for charging.

Industry uses battery cyclers - a lot of companies out there

• multichannel devices

• squidstat potentiostats - he met the guy that designed it https://www.admiralinstruments.com/product-page/squidstat-solo

Been using quite a bit of Keithley stuff

• SMU, Loads, Power supplies

@Micah Black to send Dale info on the Python code and the Keithley Rpi app note

Toyota Prius had NiMH batteries - literally a process he developed. Cars that fail typically with one module bad

DAQ, Loads, Power Supplies, all connected. Excel VBA system will connect to it - come back next day and he’ll have all the data.

Macros - to ‘mine the data’

Charging time, etc. 3rd charge - what's the highest voltage, etc.

Manufacturer cells - some of the cells might be different

For a full cycle, he’s expecting

Brute Force hardcore do it with circuits kind of guy

• When Tesla builds a module - (public info), say 30 paralleled cells and 1 of them decides to go bad. Fusible links connected - a cell shorts and the fuse blows.

• Making sure everything is super perfectly matched - he’s not a big believer in this

• The cells will all age differently.

• Accommodate the difference with other ways

Background

• Non-traditional student, worked for a number of years

• Original team - he and a few people started a UK team 2002/2003

• Lead Acid days - built a car

• Lifelong learner - still taking classes now.

• Worked in industrial maitenance

• Lexmark, printer power supplies

• Oil company now, working with NiMH - batteries would in Hybrids - coolant fluid, batter swapout

• Always worked a full time job and went to school too.