Electrical Open Forum
- Nita E
What is something that you’ve seen teams have difficulties in?
Going from yellow → green is the most difficult. Minor stuff, mostly safely related.
Testing, validation, characterization is what trips up a lot of teams. Need to know that it works consistently.
How would you go about setting up a CAN bus? (this question is for a new team)
Look up something online idk
Have you all checked where the relays are supposed to go?
The solar relay should be closer to MPPTs than the battery - it makes more sense in this case despite defying regs.
Which parts of the regulations should be read by electrical team members?
The whole electrical section (section 8 ). Also the section describing the way the event will happen.
Trying to move from interrupt based sys to a real time OS. Advice?
No one in the forum is a FW person LOL
How does antenna interference come into play?
Antenna placement (make sure it’s exposed)
Making sure nothing around would interfere with it (ex. carbon fibre is conductive, will act as a Faraday cage)
Depending on the type of antenna, it may be helpful to provide a ground plane.
Is impedance matching ever considered in design?
Yes. VNAs are commonly used.
Books/resources for RF design?
radio module
Better antennas → better telemetry system!! This should not be brushed off.
What data do you recommend for telemetry?
latitude
longitude
# of satellites used connected to
cell voltages
state of the car (steering angle, brake/gas, etc)
CAN makes extra telemetry easier lol
Resources for designing custom BPS/BMS?
Avoid balancing - it consumes energy.
Reverse engineering. Try optimizing the original BPS design!
Designing based on regs
It takes a very long time (time to build a car)
What kind of damage can the battery pack take over the race?
They get hot, especially considering the weather. Could approach 65 C, depending on cooling.
If the driver complains about vibration, the batteries are probably feeling the same thing.
Connectors for each cells is not very good. Wires will vibrate and break off.
Cheap test: pick up the pack and drop it.
NASA publishes their workmanship standards on their website - they can be a valuable.
If you’re taking outside air into the pack for cooling, the air should be filtered.
How do you prevent people from touching the arrays?
…caution tape.
Place the tape around pylons, far enough so that people with long arms can’t reach from the other side of the taped pylons.
Or take the array off the car.
Provide an alternate piece that people are allowed to touch so that the real stuff can’t be touched.
How do you decide the wire size?
Current
Temperature
Resistance
Available supply
Does putting two wires in parallel double current rating?
Yes, but not allowed in the regs (especially for HV wires). Having more flexibility is a useful thing, but there is multi-stranded wire that we can use instead of doubling up.
Need to consider power losses, weight of wire.