Arduino Project Inside Vehicle

Projects General Guidance
1

I'm working on a small sensor board that I want to place inside an ambulance. I want the board to run when the ambulance isn't running, so I have a LiPo battery connected to an Adafruit PowerBoost 500. When the vehicle is running, I want the board to be powered, and the battery to be charged, by the vehicle.

I'm still desperately trying to wrap my head around creating the proper protection for the board, against voltage spikes and load dumps (will literally pay anyone who has time to talk to me on the phone to explain this next part).

From what I understand, I simply need a Diode placed in series with the +12V from the vehicle, along with a Zener diode placed on one end with the +12V, and at the other end, with a series resistor to ground. Along with a through-hole fuse of the appropriate size (e.g. 25V), do I have sufficient protection, or is there more that I need?

Also, to prevent the LiPo battery from trying to power the vehicle when it's off, is the first Diode I mentioned sufficient?

Thanks!

2

Save yourself a lot of angst and power direct from the main battery. The project will not draw a big current so should not drain the battery any more than what you have suggested, probably less.

Drop the voltage to 7.5v with a switching regulator. This will isolate the Arduino from vehicle spikes.

Weedpharma

3

Thanks weedpharma.

The board has a temperature sensor, and needs to trigger the vehicle to start (separate, commercial product) if it drops too low, or goes too high, so it needs to run when the vehicle is off. Some of these ambulances can go a week without being used, so I thought it best to power it from a LiPo instead of the vehicle battery.

As far as protection: a switching regulator (good example?) and I don't need any diodes, zener or otherwise?

Thanks!

4

If the board draws 100mA and runs for 150 hrs, it is only 15 Ahrs from a battery of at least 100 Ahrs.

Look here for methods of reducing the power

Power saving

You only need to test the temperature say every 10 mins so it can sleep in low power mode between tests.

There are many switch mode supplies that will easily handle this job. Do a search in Google.

Weedpharma