Car ESP32 project thoughts

Projects General Guidance
1

Need to switch some 12V lines in the car. Currently 4, potentially up to 9. Where I want to put the controls is about 3 feet from the best place to put the relays, and running more than a couple of wires from one to the other might not be too easy. I'm currently looking at using an ESP32 with touch screen ( Amazon.com: AITRIP 1PACK 3.5" inch ESP-32 ESP32S ESP32 Display ESP-WROOM-32 Resistive Touch Screen TFT LCD Module 320x480 ST7796 ESP32-3248S035C Development Board for Arduino IDE : Electronics) for the controls, communicating, presumably through ESP-NOW to another ESP32 ( Amazon.com: Teyleten Robot ESP32S ESP32 ESP-WROOM-32 Development Board 2.4GHz Dual-Core WiFi +Bluetooth 2 Function Microcontroller for Arduino (ESP32 30P, 3PCS) : Electronics ) to do the actual relay control. The only other thing that one might be doing is listening for a simple input to activate a predetermined combination of the relays.
Main goal in doing it this way is to have it totally configurable, while not having an insane number of switches that I'd then have to label, plus even then, having to keep track of them in the dark, while also not running a big bundle of wires to the control location. Relays most likely 12Pcs 1 Channel Optocoupler Relay High Level Driver Module Optocoupler Relay Module Isolated Drive Control Board 3V/3.3V Relay Power Switch Board for ESP8266 Microcontrollers Development Board: Amazon.com: Industrial & Scientific
My questions would be the following:

  • What should I expect as far as max draw and standby draw for the boards? To give it a bit of safety margin, let's assume 10 relays. Probably powering the ESP32s through USB, using a supply rated for 3A, so my main concern would be if I forgot and left them powered for several days while not driving.
  • How long would it take this setup to be ready (boards active, communications established) from power up? I'm looking at having it normally on a switched circuit, with a bypass so it can be turned on with the key off. The 12V-USB converter I'm looking at using should protect it from transients if the bypass is left on during starting.
  • Am I totally missing some vastly easier/cheaper solution?
2

The interior of a car experiences extremes of temperature. Don't assume that all displays are suitable, you need to read the specs. If there are no specs then don't buy.

Your relays will probably be switching DC therefore you need to take note of the DC switching specs which will be lower than the AC specs due to the increased arcing across the contacts.

All your boards need power wires, therefore why not uses wires for communication as well?

3

Datasheet claims the display is good to 85C. If it's hotter than that in the passenger compartment, lots of other things will be melting.
Relays are rated for 10A at 12VDC, and the circuits I'll be switching max out at 2A, with most of them under 1A.
I already have power in both locations, and running 4-10 control wires isn't really practical: it's less than 3' line of sight, but more like 10 and a lot of extra hassle if routed behind trim, under carpet, etc. The relays will be in a dead space under the center console, where I already have 10ga power leads to a fused distribution block.

4

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.