added another load swithc to turn off isolated DCDC
another thermistor comparator circtuit
precharge mosfet, discharge mosfet, discharge and charge reistors have temp control with GPIOs sent to controller boards
precharge is much quicker with decreased res values
might not need heat sinking with quick precharge and discharge
will not buy a new heat sink
add more mounting holes (other than just the four corners)
standoffs on controller board holes
temp sense connectors - combine into one 8 pin connector
DCDC
Aashmika
sim surfing tool on murata for ceramic cap capacitance curves at different voltages at different pacakges
look at for RLC filters
look at switching frequencies for motors/motor controllers, mppts, dcdc, etc. to find out the frequency you want as baseline for cutoff
will ICLs get hot enough now that they are in series
yes but double check and make note in schematic
how hot will ICLs be?
Make fault LED yellow or red and add power led as green
change power terminal to power dist. to whats agreed on with josh
Maybe dont have pullup resistor on optoisolator
should be fine though because not actual NPN
Power Select
Josh
Having trouble finding the actual load capacitor value based on equations
vout droop is set to 0.2V - should be able to handle droop of 10V
was unclear about Vdroop, but now is fine
old PD current sense resistor was rated for 7W,
place passives before opamp close and after close to op amp (dont have to worry then about the difference of impedances across nets)
maybe use op amp array
fuse was getting really hot because of the possible resistance of the fuse holder
maybe go with minifuse
current fuse is tin-nickle which may be the issue?
Other notes
Taiping
Make sure to follow battery regs and labeling and isolation and UV protection for additional battery packs for fans and horns
Telemetry
Pei
CAN-wifi device
edited confluence page
best option is ethernet to wifi router
other option is using LTE (we will have coverage for FSGP, and most of the route on ASC, so theory we can use the LTE as backup during ASC portion, and can use for FSGP)
LoRa has performance issues
Same solution as a combo of ASC 2018 and FSGP 2019
Verizon has good coverage over the rural site
___ (something other teams use apparently) is lower power than LTE
can get a rf/wifi amplifier (found some on ali baba)
want a CAN-wifi solution, b
Need to keep in mind that we want to use minimum power for the telemetry solution
maybe on term get access to esp32? and test out
UART-LTE module (maybe easier for programming wise, but limited with speed (text message once in a while))
Apparently theres open source for using router to phone connection with data through ethernet to phone - teams use this solution
wanted to use FiPy but it might use a lot of power (espunning on python
nominal is 200mA, btu more with LTE running at 3.3V (similar to esp32)
about a half a watt → maybe 5 watt/hours a day
Are we willing to spend this on the car? car capacity is 11KWhrs
apparently an extra 20W on low voltage will drop 200KM in the distance the car can run (graph made by clarke)
easy to use ESP32 and micropython setup and working on it
has can compatibility all would need is SD card and CAN transceiver
may not get lower power consumption if using LTE or wifi
ubiquity consumes about .1A for 12V (M1 bullet)
can put bullet in the chase car, but will need a directional antenna with sufficient gain in the car
chase car windshield should be fine for transmission if there is no metallic tinting on the shield, otherwise
might need telemetry stuff in Lead car
bullet M2 has been tested in e5 parking lot and worked fine (antenna was on the roof in the solar car, and chase car at few car lengths was able to receive signal)
Wants to test with GPy and antenna and follow with this otherwise backup is using the bullet (mechanical may not want something to stick out)
to test needs usb-can dongle and transceiver on breadboard with GPy and antenna
realistically dont need CAN, maybe hookup to laptop for UART with USB32 and sense with another laptop with wifi
BMS Carrier
Liam
currently has pi connector (maybe not use)
all the signals have added input output expanders, so takes up less space
keyed connectors
USE the same connector for all 12V power connectors so that testing is much easier
put kill switch on a 3pin and have a ground in case you want to run a shielded wire
relay has economizer that advertises coil suppression (may not have it, double check)
adding the TVS help opens the contactor faster, because it decreases the voltage required to open, but if you don’t need this advantage, no other use for the TVS diodes
why aren’t using the interrupts for the MCP238 → should have it if using the surrounding inputs
if want to know how fast kill switch was hit on the car, then want to connect the kill switch directly , otheriwse if nothing depends on the time at which the killswitch was hit, then you can have the delay in time through the expander (not time critical)
usually the port expander is not good for transients (like duty cycles or PWM) - depends on what you are trying to measure
so the fan sense may not be optimized through the expander
might just see changing values in registers, and not see in time whats going on
have to see how quick things being sent
the point was to check if it’s running vs. stalled
not critical to know speed, but is helpful for airflow modelling and testing at different speeds (not critical when the car is assembled but is useful for modeling)
fans are being PWMd
4wire fan 3V PWM
ADT7470 ← fans or similar that monitor speed
vias on pads required the via to be drilled then plated then copper will flow
sometimes fab does not support vias in pads
might be better to not do that
usually fill the via then cap the bottom and top then reflow
if want low esr caps, can get hybrid polymer caps to replace with aluminum caps ← would get higher inrush, but have a precharge anyways so
move the green mechanical layer bodies so they are seperate for each component
Pi is only connected to UART and power on this board
is that enough bandwidth to transmit what you need to (Arshan said it was fine)
CAN gets more overhead but UART logging quicker may be faster than using CAN then transmitting to center console
issues with flooding CAN bus
1second delay for isoSPI overhead should still be fine
isospi takes about 1second per isospi IC
if the time is going to be around the same with using the extra pi and not
Connectors
Josh
current microfit has no mechanical relief
ended up deciding on gold plating with kinked pins and board lock footpring on microfits
the board lock has a different tab footprint tho then the current microfit
right now use non board lock
board lock has the metal pegs on board mount, and can they be soldered?
probably not what designed for (press fit retention kit)
but looks like the same material as pins so maybe can solder this
josh will make footprints for all new connectors then we will send out board that has all of them on it so we can test before implementing