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HOW to prevent a dead battery

Posted: Sat Dec 15, 2018 10:05 pm
by TheMonkey
i have the V1 OBD2 adapter on order. Looks like a very cool product, thanks Spencer for offering it.

i will be using it to read coolant temps and control dual fans as well as display temps.

specs show that it draws 5mA which is acceptable for parasitic draw on battery when parked. I'd like to limit it to that, the arduino and LCD is much higher. i'd like to bring in switched power to the arduino.

is there any reason why the 5v going into arduino can't come from it's own source? it does not need to be tied to the UART adapter?


Re: HOW to prevent a dead battery

Posted: Tue Dec 18, 2018 8:35 pm
by stanley
You can turn off your Arduino and LCD when it fails to get data from OBD (for a couple of times which normally indicates ignition going off). Alternatively, you can judge from the car voltage. Normally when ignition is on, voltage is over 14V and when it's off it's below 13V.

Re: HOW to prevent a dead battery

Posted: Sun Dec 23, 2018 5:29 pm
by TheMonkey
Thank Stanley. Not sure why I read Stanley was the man behind this but my fingers typed Spencer.

I'd rather not power the Arduino with the car +12v. It's in spec, but I've read too many instances where it caused probs and a 5v buck converter fixed it.

I like the sound of your option #1.... you said turn off Arduino and LCD when data stops. Would you mind spoon feeding me any more details? Is that logic I write into the Arduino sketch? Is that a sleep mode of some kind? What logic would you recommend?

I've got my code written and the fan logic is trouble free. Very cool features written in using RPM, throttle, voltage, and of course coolant. Couple thermistors to bring in AC condenser split temps for that fan logic too. Looking forward to plugging this in. Have you considered hopping some inventory in with Amazon warehouse in US to reduce shipping and transit time? Those guys have us trained to a 'now' mentality lol.

- Scott

Re: HOW to prevent a dead battery

Posted: Thu Jan 03, 2019 8:29 pm
by stanley
Some LCDs' backlight can be turned off and then they consume very little power. Arduino's AVR MCU can be put into low power deep sleep mode (google for some useful info and code).
Sorry we don't have distributors at the moment.