Working with remote sensors. Save me from drilling a hole in my roof, please.

I have 3 Arduino's w/ sensors (temp, humidty, etc) that are mounted to the roof of a vehicle. It must be on the roof (no exceptions) and the data must go to the driver. I have so many different possible routes but I am not sure which one to go for. Which would you do?

  1. I could use Bluetooth, but then the driver would have to pair each sensor each time they enter the vehicle. Pro: most displays support bluetooth Con: Power Consumption & Pairing. How would I power it? How long would a 9v battery last?

  2. Drill a hole in the roof (eek!) and communicate via USB. Pro: No Pairing, USB will charge and handle communication Con: There's a dang hole in the roof

Summary: Sensors on a roof, which is the best method to transmit this data to the driver, who has a display?

Thanks in advance

mydogcooperisapita:

  1. I could use Bluetooth, but then the driver would have to pair each sensor each time they enter the vehicle.[

Not true. Pairing is only done once. Connecting may be automatic each time the ignition is switched on, just like your phone.

Pro: most displays support bluetooth

I have never heard of a display that supports Bluetooth.

How long would a 9v battery last?

Not very. I won't ask why you would ever consider that. Maybe your vehicle is pedal-powered.

Sorry, when I said "display" I meant PC. We have Toughbooks in our vehicles, with Bluetooth. Dang, and as I go forward with this app, I have more questions. Could I have 3 or 4 Arduinos Bluetooth to one PC at once?

As for the battery question, I was asking about Power so I can avoid drilling a hole for a USB cord to power the Arduino. How does one know how long and how much power is required to battery power an Arduino?

Sorry for the million questions. I have this device that works and I just can't figure out the best way to have it communicate with the PC inside the vehicle, if that makes sense.

mydogcooperisapita:
Could I have 3 or 4 Arduinos Bluetooth to one PC at once?

Not easily. You may be able to do it with BLE, but it is likely to simply move the problem to the PC. I'm sure you are better off having one Arduino collect data from the others and send a single stream to PC, then a simple terminal would suffice. If you ditch Bluetooth and use WiFi, I'm not sure it would make the job much easier. I won't ask why you have three Arduinos on the roof.

How does one know how long and how much power is required to battery power an Arduino?

Battery power is a black art of its own and rarely, if ever, involves seriously using a 9v PP3. The objective is power, and a PP3 doesn't have any. It depends very much on the gear and the duty cycle. At a guess, a couple of 18650s swapped daily might be in order. If you use 3.3v Arduinos, you may get by with one.

FWIW, there may be no need to actually put a hole in the roof. A common practice on cars is to feed through the B pillar. Talk to your friendly highway patrol or cab driver.