# Arduino Forum

## Using Arduino => General Electronics => Topic started by: MatejaBoy on Oct 26, 2019, 08:41 pm

Title: Can I use arduino with changing voltage power source?
Post by: MatejaBoy on Oct 26, 2019, 08:41 pm
Hi!

I have a project with an Arduino Pro Mini, and I want to power it from my motorcycle's power line.
The problem is, that since the bike has a generator which's output voltage is changing with the RPM, the power line doesn't give a constant voltage. Is it problem for the Arduino to handle this power source?

If it's a problem, how do I make this changing voltage into constant voltage?
Title: Re: Can I use arduino with changing voltage power source?
Post by: Grumpy_Mike on Oct 26, 2019, 09:55 pm
Quote
Is it problem for the Arduino to handle this power source?
What is the range of voltages you get when revving the engine?

The maximum voltage an Arduino's on board regulator will take is 12V.

Even so the current is limited to a hundred or so mA because of the thermal dissipation on the regulator chip.

Quote
how do I make this changing voltage into constant voltage?
You use a buck DC to DC converter to step down the voltage efficiently and set it to 5V and attach it to the 5V, and ground pins.

Title: Re: Can I use arduino with changing voltage power source?
Post by: MatejaBoy on Oct 26, 2019, 11:40 pm
I am sure yet about the range of voltage, but I think the voltage is always between 12V and 17V. I am gonna try a buck converter, thanks for fast response :)
Title: Re: Can I use arduino with changing voltage power source?
Post by: gilshultz on Oct 28, 2019, 10:44 pm
Yes! Please note the arduino board can operate on an external supply from 6 to 20 volts however If the supply is less than 7V,  the 5V pin will start to supply less than five volts and the board may become unstable. If using more than 12V, the voltage regulator may overheat and damage the board, this is very much dependent to what load is connected to the 5V supply. The recommended range is 7 to 12 volts. Consider a SEPIC converter, it is just a little more and you will like the results.  Please be aware there is also the possibility of Load Dump which you need to protect against.  The initial value I worked with many years ago was 80V with lots and lots of amps available. This is not a steady state condition, just a bad transient.   put the transient protection in front of the converter.  Some will not need it and may be reverse battery protected. There is a nice article at:
Good Luck and Have Fun,
Gil
Title: Re: Can I use arduino with changing voltage power source?
Post by: SteveMann on Oct 28, 2019, 11:36 pm
If the motorcycle battery voltage is only over 14V for a short period (a few seconds over a minute), you can use this all day.  The on-board regulator is rated to 20V, but there is no heat sink on it.  I run some Uno's all day on 12V wall warts with no issue.

Unless the motorcycle has no battery, then you do need some kind of protection.
Title: Re: Can I use arduino with changing voltage power source?
Post by: TomGeorge on Oct 29, 2019, 09:29 am
Hi,
Do you have a DMM?

Does your motorcycle have a battery?
17V sounds way to high to charge a battery.

Tom.... :)
Title: Re: Can I use arduino with changing voltage power source?
Post by: MarkT on Oct 29, 2019, 04:59 pm
Vehicle supplies can have voltage spikes and drop-outs, best to clean it up first by filtering, or using a DC-DC converter which also allows voltage conversion.