Hi i am new to arduino. Sorry for this noob question.
I have a project that i have been working on. A keyless system for my motorcycle using bluethoot. I been finding some dc to dc converter for the battery and the arduino. But i have my doubts on choosing one. Can someone please give me any suggestions which is the best dc to dc coverter on my case with high battery efficiency.
I just dont want my motorcycle to caught on fire. Hehe
Thank you for any suggestions.
You did not pick an easy problem. Your current consumption will be your problem which you have already figured out. Have you worked out how to keep the Arduino power low? It pulls a lot of current for this application however you can have it go to sleep and wake up to check. What bluetooth devices have you looked at? There are ESP32. There is also the HC-05 bluetooth module. While you are checking current consumption also look at SEPIC (Buck Boost) converters they will be a big help if the battery voltage goes low.
This project Cheap NMEA/AIS Hub to Wifi Bridge used an MPM3610 3.3V Buck Converter module based which seems to have ~70% efficiency but very low quiescent current and a 4.5V to 21V input range.
If you want really low power BLE then use this design
Easy Very Low Power BLE in Arduino which uses <100uA continuously both while waiting for a connection and while connected and sending/receiving data.
so your total current usage will be <300uA (including a latching relay)
Being a keyless system the circuit will have to be running 24/7. I realize the Arduino and BLE will be in some sleep mode but a buck converter will have to run all the time.
I would look at a micro power linear regulator. They draw extremely low power when the load is low. When the load is running it may burn more power than a buck converter but I would expect the circuit will be in sleep mode for all but a few moments.
With a quiescent current of 200uA, I suspect the buck converter goes to sleep as well 
BUT @JohnRob suggestion of a linear solution is better
see https://www.digikey.com.au/product-detail/en/maxim-integrated/MAX16910CASA9-V-T/MAX16910CASA9-V-TCT-ND/8024189 which as a 20uA quiescent current.
You may be correct, I'm not sure. However it is hard to imaging a switching powersupply going to sleep yet still supplying power to the arduino and BLE
It transitions between various modes as the load drops. There is a separate spec for shut down of 1uA. This doc defines Quiescent Current https://www.ti.com/lit/an/slva079/slva079.pdf?ts=1625978089822
as all the current that is not supplied to the load.
"going to sleep" was my sloppy term for what it does at no load.
The Very Low power BLE circuit and code uses very little power so the converter is very close to a no load condition. BUT there are bound to be some switching extra losses even at 100uA load.
I hope your project has nothing to do with the ignition or fuel systems…
Running a promiscuous wireless system for an uncertified life-dependency system sounds risky, and will possibly void any insurance you’re carrying.
I see your point. Perhaps if the design could only enable the ignition and not disable it could be made safer.
This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.