[chbot] Car 12v supply to 5v VCC.

Daniel Powell danielvieway at hotmail.com
Tue Jul 9 04:44:58 BST 2019

Geoff, given your location (I’m in Gardiners road) you and I should talk over a light beverage. Would especially like to know how you are successfully shutting down your Pi and avoiding card corruption. Or even what you are using as a canbus transceiver (my PiCan is a little bulky). I’ve benched wireless telemetry and NMEA via my Pi, haven’t transferred it to the race car yet. Thinking I should port it to an Orange Pi and run everything on EMMC (will also avoid any vibration issues with the SD card)

The offroad race car alt is a 110amp and barely able to keep up with the arrays of large fans and the occasional times I install the lights.
The rules also require you to electrically isolate everything on kill. Even though I have a high resistance dump to ground when the kill switch is activated it occasionally pops the alt regs. Not the best of environments. I’m thinking of sneakily running the main alt line on a fused link and run the ECU, coils, pumps, etc, through a two pole kill switch…. Not legal, but at least I won’t keep on blowing alts with the 6 pole kill switch. It’s a new car, and a work in progress.


The dash is currently designed to be installed within the steering wheel. However I think for the first installation I’ll mount one in the central console in the rally car (pic below) such that both the driver and co-dog can read it. It’ll also allow ease of replacement or configuration given it’s in an enclosed cabin.


Thanks for all the assistance gentlemen.


From: Chchrobotics <chchrobotics-bounces at lists.ourshack.com> On Behalf Of Geoff
Sent: Sunday, 7 July 2019 7:35 PM
To: Christchurch Robotics <chchrobotics at lists.ourshack.com>
Subject: Re: [chbot] Car 12v supply to 5v VCC.

You can actually find 12->5v step downs locally in NZ for cheap enough. All car USB converters do exactly this, and can be had on trademe for a couple dollars: https://www.trademe.co.nz/computers/cables-adaptors/usb/listing-2220387680.htm<https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.trademe.co.nz%2Fcomputers%2Fcables-adaptors%2Fusb%2Flisting-2220387680.htm&data=02%7C01%7C%7C8e53c47e3db34b76bd1908d702adb305%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636980817374994911&sdata=g3JCdKLeErIfD1kF6JGapupIz6mZuv04ZtPEGtPgrCU%3D&reserved=0>
If you have a dollar-store-thing near you, they probably have them as well for $4-5. In bishopdale mall there's a "Party Dollar Store" that I used to pick up this sort of thing from.

Even if you're not using it in the cabin of the car, you can open it up and extract the PCB so you can solder wires to it. The ones I used had a single screw that held the whole thing together.

Is the output stable? Well, from a clean 12V supply, I've been running a raspberry pi for the past two years, and it's still working. No idea about what a racecar would do to it.

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