I'm running and Arduino Uro R4 to drive a stepper motor.
I've got a 24V RC car battery that I split off.. 24 volts to the stepper motor board and to a buck convertor that drops the 24V to 5V that I then use a barrel jack plug to power the arduino... seems to be working fine... not sure where I found the suggestion to use a buck convertor.
So things are working.. and I'm building a second setup and thought.. the barrel jack can have input of 24v... why do I have the buck convertor board... do I really need it?
Only reason would be actual battery voltage. Battery has a range, fully charged battery can have noticeably higher than nominal voltage. It could exceed 24V.
So how is your battery ? Chemistry and how many cells in series?
Because 24V is the absolute max and you never want to run electronic equipment at the maximum limits. To be safe you should limit the input to say 21.5V +/-10%
he's right, a 24V battery usually chargers to a little more than 24v... so if 24v is the upper limit.. a fully charged battery could damage the adruino... so you want to be 24v max... if your tolerance on components adds up to 10%... 21.5+/- 2.15 volts.. would ensure under the worse case you don't exceed 24v... as the arduino only needs 6v or above (though I'm driving mine at 5v) it's better to be safe than sorry
This doesn't have to be too complicated. Post you battery specs (or calculate max voltage by yourself).
If your battery voltage max above 24V, use external buck converter rated for higher voltage (be aware of all components, even arduino R4 buck is rated up to 40V).
If battery max is 24V go ahead without. There's no need to invent new numbers and +- tolerances here.
Arduino may have been going after some business in the world where 24 volts rules.
IMO they bungled that if it was at all the point.
As @jim-p has told us, playing at maximums is aasking for trouble.
The regulator IC is good to 40 volts, but they used 25 volt capacitors in the design, so 24 volts is still unconfortably close, not to mention the barrel jack, which might be technically limited to 12 volts.
I think I'll just keep the buck convertor for now.. if I build a third one.. I may try it with the battery going straight into the arduino as a test run
