Powering imp via car electrical system

I see the April dev board can handle a voltage from 3.3 to 17 volts. I’m curious to know if there are any cautions/recommendations about powering it directly via a 12vdc car/boat electrical system in the corresponding vehicle.

On the boat front, I have a friend who has experienced issues with his battery draining due to some unknown load. There is WiFi at the marina. I was considering offering him a quick solution to notify him when the battery drops below a specified voltage. It could also be used to alert of potential freeze conditions if his heater fails during the winter months.

On the car front, I was considering getting engine data whenever the car is in/near the garage via an appropriate OBD adapter. I haven’t really given this one much thought, but I’m still curious to know if there are cautions about power.

Should not be a problem to connect it to their batteries. As long as they stay within the range the regulator is capable of handling.

Car electrical systems do nasty things. I’d recommend (a) a 100v diode in series with the power input (to catch negative voltages) and (b) a 16v transient suppressor across VIN/GND. You can see load dumps of 100-200v when turning off a car; I know nothing about boat electrical systems though!

Really, you want to have a higher rated PSU to give more headroom for the transient suppressor (eg varistor, tranzorb, etc) to work before the PSU helpfully self-destructs.

Or, easy option: buy a phone charger and run the imp from that. The charger will have all this stuff inside it alrady.

Try opening a cheap phone charger. :wink: 7805 inside, maybe a resistor to make the phone charge faster, and overheat the 7805.

I had another supply in my old car to power an arduino, after 5 years it still was running fine. But I never checked how well it worked, regarding noise and such. It just did the task I had it to do.

Very helpful feedback! This forum is great! I think I’ll go the phone charger route.

You say the marina has WiFi …

To access their WiFi, do you have to pick the ID from the wifi list and enter the password … just like the WiFi in your house?

Or do you have to access a “webpage” they have, using your browser, where you log-in?

The webpage type of access is “captive WiFi”, and you won’t be able to use the imp.

Yes, I’ve encountered that issue numerous times at our customer sites. I’m hoping they don’t require acknowledging appropriate Internet behavior via a webpage. The other issue I come across (as recently as this AM), is a “guest” network that only allows port 80 traffic.