Tiernan's Comms Closet

Geek, Programmer, Photographer, network egineer…

Raspberry Pi in a car, part 2

For the last few weeks, I have been running a Raspberry Pi in my car, along with a small UPS and a Wifi Access point, allowing me to download videos from my dash cam and back them up to my NAS in the house. But I have had some teething issues, and I am currently thinking my way through some fixes…

  • First, the Pi is connected to both the network in the car (via ethernet) and network in the house (via Wifi). It seems that when the car is parked outside, sometimes the Pi can’t talk to the internet, and sometimes it can’t talk to the dashcam… It’s a routing issue, and it’s starting to annoy me…
  • I thought the onboard Wifi on the Pi was a little weak… it wasn’t getting much more than about 2-3Mbytes/s (16-24MBit/s) when downloading from the Pi to the House. Given the Pi was serving content from an SSD (not the internal MicroSD) I would have hoped for faster. I tried swapping in an external Wifi dongle with an aerial, but the same kind of speed… must be having issues getting through the metal and glass in the car, plus the metal, glass and brick in the house…
  • I started running out of disk space on the SSD on the Pi after about 3 or 4 weeks of video… so, I needed to tweak the command for the download script to only keep 14 days on the pi. Resilio Sync, the app I use to sync back to the house, has a “keep deleted files in an archive” folder option, so when the pi does delete the files, they are still stored on the Pi… I would like to find a way of automating that…

While trying to figure out how to fix part 1, I came up with an idea: I have an older Mikrotik RB951G that can be powered via a 12v adapter for the car. I am going to use that, along with a Huawei 4G dongle to act as an internet connection. The onboard Wifi will be in client mode, so when it’s near the house, it will connect to the main network and send traffic through that to the internet (or internal NAS) and when away, use the LTE modem. Then, using the Wifi dongle on the Raspberry Pi, use that as a Wifi AP.

Anything in the car that needs Wifi will connect to the Pi, which will act as a bridge to the Mikrotik. When the script needs to download files from the dashcam, it should have a direct connection to it, plus (hopefully) will be faster… then the Pi is connected to the internet through the Mikrotik. The Pi has both Tailscale and Zerotier on it for remote management, and the Mikrotik can be configured to use Wireguard to connect back to the house directly if required.

I have some of this working on a bench in the house, but it will be a while before I manage to get this running fully… Hopefully, I will have some more stuff sorted this weekend…

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